124 free calculators for better growing
Garden calculators that turn plans into harvests
Work out soil, mulch, spacing, seed, water and materials for any garden project in seconds, with drawings, shopping lists and every formula shown. Free, private and built for real gardens.
Calculators
Free garden calculators for every job
Pick a category or start with a popular tool. Every calculator gives you a result as you type, a diagram and a list of what to buy.
Raised Bed Soil Calculator
How much soil mix fills your raised beds, split into topsoil, compost and aeration.
Gives youvolume · mix · bags · bulkSpacingPlant Spacing Calculator
How many plants fit a bed in a square grid, rows or triangular pattern, with a plan view.
Gives youplants · rows · layoutSpacingSquare Foot Garden Planner
Plan a square foot garden grid: squares per crop, plants per square and a coloured layout.
Gives yougrid layout · plants · free squaresSoil & mulchMulch Calculator
Bags or bulk mulch for your beds and borders at the depth you choose.
Gives youvolume · bags · coverageLawnGrass Seed Calculator
Grass seed for a new lawn or overseeding, by grass type and area.
Gives youseed weight · bags · rateHarvest planningFamily Vegetable Planting Calculator
How many plants of each vegetable to grow for your household, and the space they take.
Gives youplants · weekly harvest · bed areaFlowersWeekly Bouquet Production Planner
Work back from bouquets per week to the flower plants and sowings you need.
Gives youstems/week · plants · sowings · bed areaTimingLast Frost Date Calculator
Your average last spring frost and the safe dates to sow and plant out.
Gives yousafe date · spring timelineFertilizerSoil pH Calculator
How much lime to raise, or sulfur to lower, your soil pH to the level your plants need.
Gives youlime or sulfur · rate · applicationsSoil & mulchCompost Calculator
Compost for top-dressing, new beds or lawns, in bags or bulk.
Gives youvolume · bags · weightWaterSprinkler Calculator
How many sprinkler heads a rectangular lawn needs, which types, and how many zones.
Gives youheads · layout · zonesWaterRain Barrel & Rainwater Harvesting Calculator
Rainwater collected from your roof per storm and per year, and how many barrels to fill.
Gives youlitres or gallons · barrelsFlowersBouquet Stem Recipe Calculator
Turn a bouquet recipe into an itemised stem shopping list for any number of bouquets.
Gives youstem list · recipe card · totalsFlowersWedding & Event Flower Quantity Calculator
Total stems for bouquets, buttonholes, centrepieces and ceremony pieces, split by flower type.
Gives youtotal stems · per piece · focal/filler splitFlowersCut-Flower Succession Sowing Planner
Sowing dates for back-to-back flower batches, worked out from the date you want blooms.
Gives yousowing dates · bloom windows · batch countFlowersFlower Farm Stem Revenue Estimator
Estimate sales from your cut-flower plants: saleable stems, gross sales and what is left after costs.
Gives yousaleable stems · gross sales · contributionFlowersDried Flower Bunch & Drying Space Calculator
How many bunches your stems make and how much hanging line you need to dry them.
Gives youbunches · drying lines · hanging lengthFlowersFlower Subscription (CSA) Planner
Plan a bouquet subscription: stems to cut each week, bouquets per season and sales.
Gives youstems/week · bouquets · salesFlowersWildflower Meadow Seed Calculator
How much wildflower seed to sow for a meadow patch, border or lawn conversion.
Gives youseed weight · packs · sowing planSmall spaceVertical Garden Pocket & Soil Calculator
Pocket count, plants and how much potting mix a vertical planter needs.
Gives youpockets · plants · soil · bagsSmall spaceWindow Box Planting Calculator
How many plants fit your window box, with a top-down layout and soil volume.
Gives youplants · layout · soil · bagsSmall spaceBalcony Container Layout Calculator
How many pots fit your balcony while keeping a clear walkway, with a top-down plan.
Gives youpots · layout plan · growing area · mixSmall spaceGrow Bag Soil Mix Calculator
How much soil mix to fill your grow bags, split into compost, base mix and aeration.
Gives youtotal mix · recipe split · bags to buySmall spaceHanging Basket Plant & Soil Calculator
Trailing and centre plants for any basket size, plus the compost to fill it.
Gives yourim plants · centre plants · compostSmall spaceHouseplant Repotting Batch Calculator
Potting mix for a whole repotting day, allowing for the root balls you move across.
Gives youmix per size · total mix · bagsSmall spaceSelf-Watering Container Reservoir Calculator
Days between refills for a self-watering container, based on reservoir size and plant water use.
Gives youdays between refills · water useSmall spaceWindowsill Herb Garden Planner
How many herb pots fit your windowsill, how much mix they need and which herbs suit your light.
Gives youpots · mix · herb suggestionsSeed startingSeed Tape Length & Seed Count Calculator
How much seed tape to make and how many seeds to glue on for your rows.
Gives youtape length · seeds · glue dotsSeed startingSeedling Shelf & Tray Capacity Calculator
How many seed trays and cells fit on your grow shelf, tier by tier.
Gives youtrays · cells · tiers neededSeed startingSeed Starting Mix Batch Calculator
How much seed-starting mix fills your cell trays, split into a homemade recipe.
Gives youtotal mix · recipe split · per traySeed startingCutting Propagation Batch Calculator
How many cuttings, donor plants and trays you need to end up with a target number of plants.
Gives youcuttings · donor plants · traysSeed startingSeedling Pot-Up Soil Calculator
Potting mix, pots and carry trays for potting on a batch of seedlings.
Gives youpotting mix · bags · pots per traySeed startingBulb & Corm Planting Quantity Calculator
How many tulip, daffodil or crocus bulbs fill a bed, with planting depth and packs to buy.
Gives youbulbs · packs · depth · layoutSeed startingMicrogreens Tray & Seed Calculator
Trays to sow each week and seed to buy for a steady supply of microgreens.
Gives youtrays/week · seed · rotationSeed startingSeed Calculator
How many seeds and packets to buy for the plants or rows you want, allowing for germination.
Gives youseeds · packets · sparesSeed startingSeed Germination Calculator
Your germination rate from a paper-towel test, and how many seeds to sow per plant.
Gives yougermination % · seeds per plantSeed startingSeed Rate Calculator
Seeding rate by weight from target plants, thousand-seed weight, germination and establishment.
Gives youkg/ha or lb/acre · total seedDIY projectsPlant Support, Stake & Cage Quantity Calculator
Stakes, cages, twine and ties for tomatoes, peppers and other tall crops.
Gives youstakes · cages · twine · tiesDIY projectsGarden Trellis Material & Cut-List Calculator
Posts, rails, netting and fasteners for a cucumber, bean or flower trellis.
Gives youposts · rails · netting · cut listDIY projectsGarden Netting Cover Calculator
What size bird or insect netting to buy for a fruit cage or covered bed.
Gives younet size · panel cut list · clipsDIY projectsGarden Border & Edging Length Calculator
Edging length, pieces, connectors and stakes for square, round or custom beds.
Gives youlength · pieces · connectors · stakesDIY projectsRow Cover Hoop & Fabric Cut-List Calculator
Hoop lengths, fabric width and length, and pins for low tunnels over raised beds.
Gives youhoops · hoop length · fabric size · pinsDIY projectsGarden Path Gravel Calculator
Gravel, bark or stone for a garden path: volume, weight, bags and weed membrane.
Gives youvolume · weight · bags · membraneDIY projectsRaised Bed Lumber & Cut-List Calculator
Boards, posts, screws and a cut list for building wooden raised beds.
Gives youboards · cut list · posts · screwsDIY projectsCold Frame Build Calculator
Lid size, slope angle, boards and hinges for a sloped wooden cold frame.
Gives youlid size · angle · boards · hingesDIY projectsCompost Bay Build Calculator (Pallets or Boards)
Pallets or boards, posts and capacity for a multi-bay compost system.
Gives youpallets or boards · posts · capacityDIY projectsGarden Fence for Rabbits & Deer Calculator
Mesh, posts, gate and fixings to fence a vegetable garden against rabbits or deer.
Gives youmesh · rolls · posts · gateDIY projectsStepping Stone Path Calculator
How many stepping stones for a path at a comfortable stride, plus bedding sand.
Gives youstones · gaps · sandDIY projectsShade Cloth Size Calculator
Shade cloth size, clips and shade percentage for beds, hoops and pergolas.
Gives youcloth size · clips · shade %Harvest planningWeekly Salad Garden Planner
How many salad plants to sow, and how often, for a steady weekly harvest.
Gives youplants per sowing · schedule · bed areaHarvest planningKitchen Herb Harvest Calculator
How many basil, parsley or mint plants to grow for the herbs you use each week.
Gives youplants · space · resowingsHarvest planningSeed Saving Reserve Calculator
Seeds, pods or fruits to save for next year's planting, with germination and a reserve.
Gives youseeds · pods or fruits · plants to save fromHarvest planningGarlic Planting Calculator
Seed garlic bulbs, cloves, rows and bed space for the harvest you want.
Gives youseed bulbs · cloves · rows · areaHarvest planningSeed Potato Calculator
Weight of seed potatoes for your rows, number of plants and expected harvest.
Gives youseed weight · plants · harvestHarvest planningBerry Plants Per Person Calculator
How many strawberry, raspberry or blueberry plants to grow for your household.
Gives youplants · harvest · spaceHarvest planningCrop Yield Calculator
Expected harvest from your bed and its value at shop prices.
Gives youharvest weight · valueHarvest planningCompanion Planting Calculator
Check whether two crops are traditional companions, and see every pairing for a crop.
Gives youverdict · companions · plants to avoidHarvest planningCrop Rotation Calculator
A bed-by-year crop rotation plan for your vegetable beds.
Gives youbed-by-year table · groupsSoil & mulchTopsoil Calculator
How much topsoil to order for a lawn, bed or level-up, by volume, weight or bag.
Gives youvolume · weight · bagsSoil & mulchPotting Soil Calculator
Potting soil for several container sizes at once, with bags to buy.
Gives youvolume per pot · total · bagsSoil & mulchSoil Amendment Calculator
How thick a layer of compost or other amendment to spread to reach a target mix.
Gives youlayer depth · volume · bagsSoil & mulchGarden Volume Calculator
The volume of any bed, planter or hole in litres, cubic feet, cubic yards and cubic metres.
Gives youlitres · cu ft · cu yd · bagsSoil & mulchSoil Calculator
Volume, weight, bags and truck loads for soil, compost, sand or gravel.
Gives youvolume · weight · bags · loadsSoil & mulchTopsoil Weight to Cubic Feet Calculator
Convert a bag of topsoil, soil or mulch between pounds, kilograms, cubic feet and litres.
Gives youcu ft · litres · lb · bags per yardSoil & mulchCompost C:N Ratio Calculator
The carbon-to-nitrogen ratio of your compost mix, and how many browns to add for 30:1.
Gives youC:N ratio · browns to addSpacingPlants per Square Foot Calculator
Plant density per square foot or square metre for any spacing, plus a quick reference table.
Gives youdensity · total · tableSpacingGarden Area Calculator
Area of a garden made of rectangles, circles, triangles and ovals, in any unit.
Gives youarea · acres · conversionsSpacingGarden Bed & Path Layout Calculator
How many beds and paths fit your plot, with growing area and a plan view.
Gives youbeds · growing area · planSpacingFlower Bed Plant Calculator
Plants for a flower bed in back, middle and front zones, each at its own spacing.
Gives youplants per zone · totalSpacingPlant Population Calculator
Plants per acre, hectare and square metre from row and in-row spacing.
Gives youper acre / ha · total plants · seedsSpacingPlants Per Acre Calculator
How many plants fit an acre or hectare at square or triangular spacing.
Gives youplants per acre · total · layout gainSpacingCrop Spacing Calculator
Recommended spacing for 14 vegetables and how many fit your bed, in rows or offset.
Gives youplants per bed · spacing · planSpacingRow Spacing Calculator
How many rows fit a bed at your spacing, or the spacing for a set number of rows.
Gives yourows · spacing · total row lengthSpacingGround Cover Calculator
How many ground cover plants and flats you need for an area at your spacing.
Gives youplants · flats · plants per sq ftWaterWatering Schedule Calculator
How much to water each week after rain, split into sessions that suit your soil.
Gives youweekly water · sessions · minutesWaterIrrigation Scheduling Calculator
How many days between irrigations and how much to apply, from soil, roots and ET.
Gives youinterval · net depth · gross depthWaterIrrigation Run Time Calculator
How many minutes to run each zone to apply the depth of water you want.
Gives youminutes per zone · weekly timeWaterSprinkler Coverage Calculator
Area one head covers and the precipitation rate of your layout, with time to apply water.
Gives youcoverage · precipitation rate · run timeWaterDrip Irrigation Planner
Emitters, drip line and fittings for your rows, with total flow and zones.
Gives youemitters · tubing · zones · partsWaterDrip Emitter Calculator
How long to run drip emitters to give each plant the water it needs.
Gives yourun time · emitters · flowWaterDrip Flow Rate Calculator
Total flow of your drip system and whether your tubing can carry it.
Gives youtotal flow · capacity usedWaterDrip Irrigation Pump Calculator
The flow, total head and power a pump needs to run your drip system from a tank or well.
Gives youflow · total head · powerWaterRainwater Calculator
How much rainwater your roof collects a year and per storm, and how long it lasts.
Gives youlitres or gallons per year · per stormWaterCrop Water Requirement Calculator
Daily and weekly water use of a crop from reference ET and its crop coefficient.
Gives youdaily use · weekly use · net after rainWaterEvapotranspiration Calculator
Estimate daily reference evapotranspiration from temperature, latitude and date.
Gives youET₀ per day · per weekLawnSod & Turf Calculator
Sod or turf rolls and pallets for your lawn area, with cutting waste.
Gives yourolls · pallets · areaLawnLawn Fertilizer Calculator
Fertilizer per feed and per year for your lawn, with the spreader rate and bags.
Gives youper feed · spreader rate · bagsFertilizerLime Application Calculator
Turn a soil-test lime recommendation into the product rate and bags for your lime.
Gives youproduct rate · bags · applicationsFertilizerGypsum Calculator
Gypsum for clay or salt-affected soil, with the calcium and sulfur it supplies.
Gives yougypsum · bags · calcium · sulfurFertilizerManure Application Calculator
How much manure to spread for the nitrogen your crops need, by weight, volume and loads.
Gives youweight · volume · loads · nitrogenFertilizerOrganic Fertilizer Calculator
How much blood, bone, fish, kelp or alfalfa meal to apply for your nutrient target.
Gives youproduct · rate · N-P-K suppliedFertilizerNitrogen Calculator
How much urea, ammonium sulfate or other nitrogen fertilizer gives the actual N you need.
Gives youproduct · rate · splitsFertilizerPhosphorus Calculator
Turn a phosphate (P₂O₅) or phosphorus target into superphosphate, MAP, DAP or bone meal.
Gives youproduct · rate · N suppliedFertilizerPotassium Calculator
Turn a potash (K₂O) or potassium target into sulfate of potash, muriate or wood ash.
Gives youproduct · rate · N suppliedFertilizerFertilizer Requirement Calculator
How much of an N-P-K fertilizer meets your nutrient targets, and what is left over or short.
Gives youproduct · N-P-K supplied · gapsFertilizerFertilizer Mixer
How much liquid concentrate or soluble powder to mix into your watering can or tank.
Gives youdose · dilution · ppmFertilizerSoil Texture Calculator
Your USDA soil texture class from sand, silt and clay percentages or a jar test.
Gives youtexture class · triangle · adviceFertilizerSoil Organic Matter Calculator
How much compost raises your soil organic matter from its tested level to a target.
Gives youcompost volume · layer · bagsFertilizerSoil Moisture Calculator
Soil water content from a wet and dry sample, and how much water refills the root zone.
Gives youwater content · available water · refillFertilizerSoil Drainage Calculator
Your soil's drainage rate from a simple percolation test, with what it means for planting.
Gives youdrainage rate · perc rate · verdictIndoorGreenhouse Calculator
The heater size your greenhouse needs to stay frost-free on the coldest nights.
Gives youheater kW / BTU · heat lossIndoorGreenhouse Size Calculator
The greenhouse footprint you need for your trays and pots, with benches and a path.
Gives youlength × width · bench space · planIndoorGrow Light Calculator
LED wattage, daily light integral and running cost for your grow area and crop.
Gives youwatts · DLI · costIndoorVPD Calculator
Leaf vapour pressure deficit from temperature and humidity, and the humidity to aim for.
Gives youVPD kPa · zone · target humidityIndoorDWC Calculator
Nutrient solution, nutrient doses and air pump size for deep water culture buckets.
Gives yousolution · nutrients · air pumpIndoorAeroponics Calculator
Pump flow, misting cycles and reservoir life for low- or high-pressure aeroponics.
Gives youpump flow · cycles · top-upsIndoorHydroponic System Cost Calculator
Setup and monthly running cost of a hydroponic garden, per month, year and plant.
Gives youmonthly cost · year one · per plantIndoorGreenhouse Cost Calculator
Typical cost to build a greenhouse by size and type, with base, extras and yearly heating.
Gives youbuild cost · per sq ft · heatingTimingFirst Frost Date Calculator
Your average first autumn frost and the last dates to sow crops so they mature in time.
Gives yousow-by date · fall crop tableTimingPlanting Calendar
A personal sowing and planting calendar for 19 vegetables from your frost dates.
Gives youindoor sowing · planting out · autumn sowingTimingTransplant Date Calculator
When to sow indoors, harden off and transplant seedlings from your last frost date.
Gives yousow date · harden off · transplantTimingHarvest Date Calculator
When your crop will be ready to pick, from planting date and days to maturity.
Gives youfirst harvest · harvest windowTimingGrowing Degree Days Calculator
Daily and total growing degree days, and how long until your crop's GDD target.
Gives youGDD per day · total · days to targetTimingChill Hours Calculator
Estimated winter chill hours or Utah chill units, compared with your fruit variety's need.
Gives youchill hours · variety checkTimingSun Exposure Calculator
Whether your spot is full sun, part sun, part shade or shade, and what grows there.
Gives yousun category · day length · plant ideasTrees & costsTree Spacing Calculator
How many trees fit your plot at square or triangular spacing, with a layout plan.
Gives youtrees · density · layoutTrees & costsTree Age Calculator
Estimate a tree's age from trunk circumference and its species growth factor.
Gives youage · diameterTrees & costsOak Tree Value Calculator
An indicative landscape value for an oak using the trunk formula method.
Gives youappraised value · basic valueTrees & costsBlack Walnut Value Calculator
Board feet (Doyle rule) and an indicative timber value for black walnut logs.
Gives youboard feet · valueTrees & costsTree Removal Cost Calculator
An estimated price range to remove a tree, with stump grinding and haul-away.
Gives youprice range · breakdownTrees & costsTree Trimming Cost Calculator
An estimated price range to prune or trim your trees by size, condition and access.
Gives youprice range · per treeTrees & costsLand Clearing Cost Calculator
An estimated cost range to clear brush or woodland, per acre or hectare.
Gives youtotal range · per acreTrees & costsAcres Per Hour Calculator
How many acres or hectares per hour a mower, tiller or sprayer covers, and how long a job takes.
Gives youacres or ha per hour · job timeTrees & costsGarden Cost Estimator
The cost of setting up raised beds: frames, soil, plants, seeds and extras.
Gives youtotal · per area · budget tableHow it works
Plan it before you dig.
A few measurements turn into a practical plan: what to buy, where each plant goes and how much water your garden needs, before you lift a spade.
- 01Measure the space
Turn beds, borders and lawns into areas and volumes, including odd shapes.
- 02Space every plant
See how many plants really fit, with a drawing you can plant from.
- 03Buy it once
Get soil, mulch, seed and materials as bags, rolls or bulk loads, with a little extra built in.
How our numbers are worked out.
These are planning tools, so the method matters as much as the answer. Here is what sits behind every result.
Formulas on every page
Each result shows the equation, a worked example and the assumptions behind it, so you can check the maths yourself.
Defaults you can change
Yields, spacings and rates start from typical figures and stay editable, because your soil, climate and varieties are your own.
Metric or imperial
Switch units at any time: centimetres, metres, litres and kilograms, or inches, feet, quarts and pounds.
Private by design
Calculations run in your browser. Nothing you type is sent to us or stored, and there is no account to create.
Results are planning estimates. For drainage, fertility or structural questions, a soil test or local professional is the best next step. How we check our tools
Project planners
What are you making this season?
Cut Flowers & Bouquets
Plan stems, recipes and weekly bouquet production.
8 calculators →
Balcony & Small-Space Gardens
Window boxes, vertical pockets and container layouts.
8 calculators →
Seed Starting & Propagation
Seed tape, shelf and tray planning for indoor starts.
10 calculators →
DIY Garden Projects
Cut lists and material counts for trellises, netting and edging.
12 calculators →
Kitchen Garden & Harvest
Grow the right amount for your household, week by week.
10 calculators →
Greenhouse, Indoor & Hydroponics
Heaters, grow lights, VPD and hydroponic systems.
8 calculators →
Trees, Land & Costs
Tree spacing, age and value, plus project cost estimates.
9 calculators →Garden basics
Everyday garden maths
Soil, Compost & Mulch
Volumes, bags and bulk loads for soil, compost and mulch.
10 calculators →
Planting & Spacing
Plant counts, square foot grids and bed layouts.
11 calculators →
Water & Irrigation
Rainwater, watering and irrigation planning.
13 calculators →
Lawn & Turf
Grass seed, sod and lawn care quantities.
3 calculators →
Fertilizer & Soil Testing
Soil pH, lime, N-P-K, manure and soil tests made practical.
14 calculators →
Planting Dates & Climate
Frost dates, planting calendars, GDD and chill hours.
8 calculators →FAQ
A few things you might wonder.
Are GardenCalc calculators really free?
Yes. All 124 calculators are free to use with no sign-up, and they work on phones, tablets and computers.
How accurate are the results?
The maths is exact for the numbers you enter, and every formula is shown on the page. Real gardens vary, so treat results as planning estimates and adjust defaults such as yields and spacing to your own experience.
Can I use metric and imperial units?
Yes. Every calculator has a Metric / Imperial switch, and your numbers convert instantly when you change it.
Do you store what I type into the calculators?
No. Calculations happen in your browser. If you use the Share link button, your inputs go into the link you copy, and nowhere else.
Can I print or save my results?
Every calculator has Copy, Print and Share link buttons, and a Save button to pin the tool to Pinterest.
Which calculator should I start with?
Start with the job in front of you: Raised Bed Soil or Mulch for materials, Plant Spacing or the Square Foot Planner for planting, and the Family Vegetable calculator to decide how much to grow.
Guides
From the growing season
Longer reads on the questions a calculator cannot settle on its own: soil mixes, timing, and what to do when the numbers and the ground disagree.
Overwatered or Underwatered? How to Tell What Your Plant Needs
Drooping leaves can mean too much water or too little. Here is how to tell the difference from the leaves, soil and…
Read guideHow Often to Water Potted Plants (and How Much)
Potted plants dry out far faster than garden beds. Here is how often to water by pot size, plant and season, and…
Read guideMulch, Compost or Topsoil? What Each Does and How Much to Buy
They come in similar bags, but mulch, compost and topsoil do very different jobs. Here is when to use each, how deep…
Read guideSave plans to Pinterest
Every calculator has a Save button that pins the tool to your board, so the answer is there when you are at the garden centre.
Browse all calculators