pH Adjustment Calculator

Calculate how much lime or sulfur to add to adjust your soil pH to a target level for a given area.

How It Works

Soil pH measures acidity or alkalinity on a scale from 0 to 14, with 7 being neutral. Most garden plants thrive in slightly acidic soil between 6.0 and 7.0. When your soil pH is outside the ideal range, nutrients become less available to plants even when present in the soil.

Raising pH with Lime

If your soil is too acidic (low pH), agricultural lime (calcium carbonate) neutralizes the acidity. The amount needed depends on your soil’s buffer capacity—clay and organic soils resist pH change more than sandy soils.

Approximate ground limestone rates per 1,000 ft² per pH unit:

Lowering pH with Sulfur

If your soil is too alkaline (high pH), elemental sulfur is the most common amendment. Soil bacteria convert sulfur to sulfuric acid over weeks to months, gradually lowering the pH.

Approximate elemental sulfur rates per 1,000 ft² per pH unit:

Amendment Equivalents

Different amendments have different concentrations. The calculator adjusts using these multipliers relative to ground limestone (for raising) or elemental sulfur (for lowering):

Plant pH Preferences