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Planning tool

Lawn Lime Calculator

Enter your soil pH, grass type, and soil texture to get pounds of lime (or sulfur, if your pH is high) per 1,000 sq ft, the total for your lawn, bag counts, and how to split it safely.

Tool inputs

2 minutes
Location
Grass type
Lawn details
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How much lime (or sulfur) your lawn needs

Lime application rates by soil type

Pounds of pelletized lime per 1,000 sq ft to raise pH, from university extension rate tables.

Clay soils buffer harder against pH change, so they need roughly twice the lime of sandy soils for the same pH shift. These are the same rates the calculator above uses; enter your numbers to get the total for your exact lawn size.

Swipe sideways to see every column.

pH increase neededSandy soilLoamClay
+0.5 pH25 lbs40 lbs60 lbs
+1.0 pH50 lbs80 lbs120 lbs
+1.5 pH75 lbs120 lbs180 lbs
+2.0 pH100 lbs160 lbs240 lbs

Rates over 50 lbs per 1,000 sq ft are split into multiple applications, 4-6 months apart, re-testing between. Sourced from university extension agronomy tables; the same engine powers our Soil Test Analyzer.

Calcitic or dolomitic lime?

Both raise pH by the same amount. The difference is magnesium: dolomitic lime adds it, calcitic does not. If a soil test shows low magnesium, choose dolomitic. If magnesium is adequate or high, calcitic avoids pushing it further and is the safer default. Not sure? Calcitic pelletized lime is the safe pick, and the advanced option in the calculator adjusts the recommendation when you know your magnesium level.

Lime moves pH slowly. Expect the change over 3 to 6 months, water it in after spreading, and re-test before adding more. Pelletized lime is grass-safe at these rates, so there is no need to keep kids or pets off once it is watered in.

Lowering soil pH with sulfur

If your soil is more alkaline than your grass likes, the calculator flips to elemental sulfur. Sulfur lowers pH more slowly than lime raises it, because soil bacteria have to convert it first, so it is applied in smaller amounts (never more than 10 lbs per 1,000 sq ft in one pass) and re-tested each season. Use elemental sulfur rather than aluminum sulfate on lawns; aluminum can build up to harmful levels with repeated use.

Frequently asked questions

How much lime per 1,000 sq ft?

It depends on your soil and how far pH needs to move: roughly 25 lbs (sandy), 40 lbs (loam), or 60 lbs (clay) of pelletized lime per 1,000 sq ft for each 0.5 point of pH increase. A typical acidic loam lawn that needs to come up a full point runs about 80 lbs per 1,000 sq ft, split into two applications because anything over 50 lbs should not go down in a single pass.

When should I apply lime?

Fall is ideal. Winter freeze-thaw cycles carry lime down into the root zone, so pH is corrected by the spring feeding season. Spring works too; just avoid applying lime within about two weeks of a nitrogen fertilizer, since the two can interfere with each other.

Calcitic vs dolomitic lime: which do I need?

Both raise pH by the same amount. The difference is magnesium: dolomitic lime adds it, calcitic does not. Choose dolomitic only if a soil test shows low magnesium. If magnesium is adequate or high, calcitic avoids pushing it further. When in doubt, calcitic pelletized lime is the safe default.

How do I lower soil pH?

Use elemental sulfur, at roughly 5 lbs (sandy), 8 lbs (loam), or 12 lbs (clay) per 1,000 sq ft for each 0.5 point of decrease, never more than 10 lbs in a single pass. Set your current pH above your grass’s range in the calculator and it flips to a sulfur recommendation automatically. Avoid aluminum sulfate on lawns; it works fast but is harsh on roots.

How often should I re-test soil pH?

Re-test 6 to 12 months after an application to confirm the change, then every 2 to 3 years for maintenance. Sandy soils drift faster than clay, so check them on the shorter end of that range.

Does centipede grass need lime?

Usually not. Centipede prefers acidic soil (about pH 5.0 to 6.0), so a reading that would call for lime on fescue is often perfect for centipede. This calculator sets the target pH per grass type, so it will tell you to hold off when your soil is already right for centipede.