Soil pH Amendment Calculator
Calculate how much lime or sulfur you need to bring your soil to the ideal pH. Rates are based on current pH, target pH, and soil texture.
How It Works
Soil pH measures how acidic or alkaline your soil is on a 0–14 scale. Most vegetables grow best between pH 6.0 and 7.0 because that's where essential nutrients are most available. If your soil is too acidic, add lime (calcium carbonate). If it's too alkaline, add elemental sulfur.
Why Soil Type Matters
Clay soils have a high buffering capacity — they resist pH change because clay particles hold onto hydrogen ions. Sandy soils have low buffering, so small amendments cause large pH swings. That's why clay needs up to 3× more lime per pH point than sand.
Tips for Applying Amendments
Lime: Work into the top 6–8 inches of soil. It takes 2–6 months to fully react, so apply in fall for spring planting. Water it in well.
Sulfur: Elemental sulfur is converted to sulfuric acid by soil bacteria over weeks to months. Apply in advance of planting. Aluminum sulfate works faster but adds aluminum which can be toxic to some plants.
Retest: Always retest your soil pH 3–6 months after amending to verify the change.