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Use this free lawn lime calculator to figure out how much lime your lawn needs before you buy a single bag. Enter your lawn size and the numbers from your soil test, and you’ll get the total pounds, the number of bags, and how many applications to split it into. If your soil test says you don’t need lime, the calculator will tell you that too.
How much lime does your lawn need?
Enter your lawn size and the numbers from your soil test. You’ll get the pounds of lime, the number of bags, and how many applications to split it into.
Your lawn
Your soil test
Your lime
- Total lime—
- Rate for your lime—
- Applications—
- Each application—
Only lime when a soil test calls for it. Purdue says most Indiana lawns don’t need lime, and a pH between 6.0 and 7.5 doesn’t need changing. Established lawns get no more than 100 lb per 1,000 sq ft at a time. Never use hydrated lime on a lawn.
| Recommendation | 2,500 sq ft | 5,000 sq ft | 10,000 sq ft |
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Enter your own lawn size and soil test numbers above for an exact count.
WHAT’S IN THIS GUIDE
How to Use the Lawn Lime Calculator
The lawn lime calculator works in 3 easy steps:
- Enter your lawn size. Use the square footage of the grass only, not the house, driveway, or garden beds. Our square footage calculator can help if your yard isn’t a simple rectangle.
- Enter your soil test results. Type in your soil pH and the lime recommendation from the report, then pick the unit the lab used: pounds per 1,000 square feet, pounds per acre, or tons per acre.
- Enter your lime. Find the calcium carbonate equivalent (CCE) on the bag label and pick your bag size. If the bag doesn’t list a CCE, leave it at 100.
The result shows how many bags to buy, the total pounds, and how many separate applications to spread it over so you don’t put down too much at once.
Test Your Soil Before You Lime
Here’s the part most bag labels skip: a lot of lawns don’t need lime at all. Purdue Extension says most Indiana soils under turfgrass don’t need liming, and that a soil pH between 6.0 and 7.5 doesn’t need adjusting. Purdue’s advice is blunt: don’t apply lime unless a soil test recommends it. Source: Purdue Extension — Soil Testing for Lawns (AY-18)
Adding lime to a lawn that’s already at a healthy pH wastes money, and adding it to an alkaline lawn pushes the pH in the wrong direction. That’s why the lawn lime calculator asks for your soil test numbers instead of guessing.
A home soil test kit is a quick, cheap way to check your pH. If it comes back at 6.0 or higher, you can stop there. If it’s below 6.0, send a sample to a lab. A pH number alone can’t tell you how much lime to use, because some soils resist a pH change more than others. Purdue says that when the pH is below 6.0, the lab runs a lime index to make a more accurate recommendation. Source: Purdue Extension — Soil Testing for Lawns (AY-18)
Purdue doesn’t test soil for homeowners, but its Marion County Extension office lists commercial labs that do, including A&L Great Lakes Laboratories in Fort Wayne. Call the lab first to confirm its current forms and fees. Source: Purdue Extension Marion County — Soil Testing Labs
How to Take a Soil Sample
A good sample gives you a good recommendation. Purdue’s steps for lawns:
- Use a small shovel or soil probe and sample to a 3-inch depth.
- Take 10 to 15 samples from around the lawn and mix them together in a clean bucket.
- Remove the thatch and grass from each sample before you mix it.
Your county Purdue Extension office can give you forms and sample bags. Source: Purdue Extension — Soil Testing for Lawns (AY-18)
Reading the Lime Recommendation on Your Soil Test
Labs don’t all use the same units, which is where most people go wrong when figuring out how much lime to buy. Your report will list the lime recommendation in one of these ways:
- Pounds per 1,000 square feet. This is the easiest. Enter it as is.
- Pounds per acre. Divide by 43.56 to get pounds per 1,000 square feet. A recommendation of 2,000 pounds per acre is about 46 pounds per 1,000 square feet.
- Tons per acre. Multiply by about 46 to get pounds per 1,000 square feet.
The calculator does these conversions for you when you pick the unit. If you get a number that looks way too high, check the unit first. The calculator shows a warning when the rate is over 250 pounds per 1,000 square feet.
Lab recommendations also assume pure limestone with a CCE of 100 percent. Penn State Extension explains that if your lime is weaker, you need more of it: divide the recommendation by your lime’s CCE and multiply by 100. For example, a 75-pound recommendation with lime rated at 80 percent CCE takes about 94 pounds. Source: Penn State Extension — Liming Turfgrass Areas
How Much Lime Can You Put Down at Once?
Not all of it, if your soil test calls for a lot. Purdue says no more than 100 pounds of agricultural lime per 1,000 square feet should go on an established lawn at one time. Source: Purdue Turfgrass Science — Changing Soil pH Under Turf
When your lawn needs more than that, Penn State recommends splitting it into spring and fall applications at the maximum rate until you’ve put down the full amount. The calculator splits it for you and shows how much goes down each time. Source: Penn State Extension — Liming Turfgrass Areas
New lawns are the exception. Penn State says you can apply the full amount at once if you work it into the top 4 to 6 inches of soil before you seed. If you’re starting a new lawn, choose “New lawn” in the calculator. Our guide to improving clay soil covers working amendments in before planting.
When and How to Spread Lime
Lime can go down any time of year, but Penn State says it works best when applied in the fall. Purdue adds that spreading lime right after you aerate helps it work faster, because it gets into the holes and closer to the roots. Source: Purdue Turfgrass Science — Changing Soil pH Under Turf
For most homeowners, pelletized lawn lime is the easiest choice. Penn State notes that pelletized lime spreads easily in regular drop or spinner spreaders, while finely ground limestone tends to clump and clog drop spreaders. Source: Penn State Extension — Liming Turfgrass Areas
A broadcast spreader works well for most home lawns. For even coverage, set the spreader to about half the rate and walk the lawn twice, the second time at a right angle to the first.
Use agricultural lime only. Purdue warns never to use hydrated lime or quick lime on a lawn, because high rates can burn the grass. Source: Purdue Extension — Soil Testing for Lawns (AY-18)
Lime works slowly, so don’t expect a quick green-up. Purdue says to retest in 3 years to check the change in pH. If your lawn needs lime over several years, retest every other year to track progress. Lime is also not a fertilizer. For feeding the lawn, use our fertilizer calculator.
What If Your Soil pH Is Too High?
Some Indiana lawns have the opposite problem: a pH above 7.5. Lime will make that worse. Purdue says sulfur can lower the pH, but no more than 5 pounds of sulfur per 1,000 square feet should go down at one time on grass mowed at 2 inches or higher, and no more than 10 pounds per year. Source: Purdue Turfgrass Science — Changing Soil pH Under Turf
Even then, it’s slow. Purdue notes that typical Midwest soils are packed with calcium, so lowering their pH can take many years. For most lawns, a good feeding schedule does more than chasing the pH number.
Frequently Asked Questions About the Lawn Lime Calculator
How much lime do I need for 1,000 square feet?
It depends on your soil test. Penn State’s lime tables for turf run anywhere from 10 to 250 pounds per 1,000 square feet, so never guess. Enter your soil test result in the lawn lime calculator above to get the exact amount.
How many bags of lime do I need for my yard?
Multiply your soil test rate by your lawn size in thousands of square feet, then divide by the bag size. A 5,000-square-foot lawn that needs 50 pounds per 1,000 square feet takes 250 pounds, or 7 bags of 40-pound lime.
Can you put too much lime on your lawn?
Yes. Too much lime can push the pH too high, which makes it harder for grass to take up nutrients like iron. Purdue says to stay at or under 100 pounds per 1,000 square feet per application on an established lawn and to lime only when a soil test calls for it.
When is the best time to put lime on a lawn?
Fall is best. Lime works slowly, and fall gives it all winter to start working into the soil. Spreading it right after you aerate helps it work faster.
Should I water in lime after spreading it?
Yes, a light watering or a gentle rain helps pelletized lime break down and wash off the grass blades and into the soil.