Fertilizer & Soil Testing Calculators

Which fertilizer calculator do you need?

• Soil pH Calculator: How much lime to raise, or sulfur to lower, your soil pH to the level your plants need.
• Lime Application Calculator: Turn a soil-test lime recommendation into the product rate and bags for your lime.
• Gypsum Calculator: Gypsum for clay or salt-affected soil, with the calcium and sulfur it supplies.
• Manure Application Calculator: How much manure to spread for the nitrogen your crops need, by weight, volume and loads.
• Organic Fertilizer Calculator: How much blood, bone, fish, kelp or alfalfa meal to apply for your nutrient target.
• Nitrogen Calculator: How much urea, ammonium sulfate or other nitrogen fertilizer gives the actual N you need.
• Phosphorus Calculator: Turn a phosphate (P₂O₅) or phosphorus target into superphosphate, MAP, DAP or bone meal.
• Potassium Calculator: Turn a potash (K₂O) or potassium target into sulfate of potash, muriate or wood ash.
• Fertilizer Requirement Calculator: How much of an N-P-K fertilizer meets your nutrient targets, and what is left over or short.
• Fertilizer Mixer: How much liquid concentrate or soluble powder to mix into your watering can or tank.
• Soil Texture Calculator: Your USDA soil texture class from sand, silt and clay percentages or a jar test.
• Soil Organic Matter Calculator: How much compost raises your soil organic matter from its tested level to a target.
• Soil Moisture Calculator: Soil water content from a wet and dry sample, and how much water refills the root zone.
• Soil Drainage Calculator: Your soil's drainage rate from a simple percolation test, with what it means for planting.

Every tool works in metric or imperial units, shows its formula and a worked example, and lets you edit the assumptions that vary from garden to garden. Results stay on your device; nothing you enter is stored.