Lime Calculator
A lime calculator divides lawn area by 20 sq ft per pound, the 50 lb per 1,000 sq ft rate: a 50 × 20 ft lawn needs 50 lb, about $6 at $0.12 a pound.
Lime calculator: area divided by 20
A lime calculator divides your lawn’s square footage by 20 to get pounds of lime, because the rate used here is 1 lb for every 20 sq ft, the same as 50 lb per 1,000 sq ft. A 50 × 20 ft lawn is 1,000 sq ft, so it needs 50 lb, which costs about $6 at $0.12 a pound.
This is a maintenance rate for ground limestone on a lawn. It is a starting point, and your soil test result takes priority over it.
The formula in plain words
Area in square feet = length × width. Pounds of lime = area ÷ 20. Cost = pounds × your price per pound. This calculator does not add a waste allowance, since lime is spread by weight and the leftover just goes to the next application.
Worked example, a small front yard
The lawn is 50 ft long and 20 ft wide, and lime is $0.12 a pound.
- Area: 50 × 20 = 1,000 sq ft
- Lime: 1,000 ÷ 20 = 50 lb
- Cost: 50 × $0.12 = $6.00
That is one 50 lb bag, so you buy one and spread it all.
Worked example, a large lot
A back lawn is 100 ft × 80 ft, for 8,000 sq ft.
- Lime: 8,000 ÷ 20 = 400 lb
- Cost: 400 × $0.12 = $48.00
- Bags: 400 ÷ 50 = 8 bags of 50 lb
Eight bags is heavy to carry. Plan the spreader fills in advance, and keep the stock under cover until you use it, since wet lime clumps.
Lime by lawn area
| Lawn area | Lime needed | 50 lb bags | Cost at $0.12/lb |
|---|---|---|---|
| 250 sq ft | 12.5 lb | 0.25 | $1.50 |
| 500 sq ft | 25 lb | 0.5 | $3.00 |
| 1,000 sq ft | 50 lb | 1 | $6.00 |
| 2,000 sq ft | 100 lb | 2 | $12.00 |
| 5,000 sq ft | 250 lb | 5 | $30.00 |
| 10,000 sq ft | 500 lb | 10 | $60.00 |
How to measure the lawn
- Measure the grass, not the whole lot. Leave out the house, driveway and beds.
- For a curved edge, treat it as a rectangle and subtract the odd corners, or split the lawn into two or three rectangles and add them.
- Include side strips and the area behind the garage if they get seeded or mowed.
- Square footage can also come from an online map tool or a survey drawing if you have one.
Common mistakes
- Skipping the soil test. Without it, you may add lime a lawn does not need.
- Spreading too much in one pass. Heavy single doses can burn a lawn or lift pH too far. Spread the recommended amount in two passes at right angles if the amount is large.
- Treating lime as a quick fix. It takes months to adjust pH, so patience matters.
- Confusing lime with the product sold for other jobs. Hydrated lime and quicklime are caustic and not interchangeable with garden limestone. Use the product made for lawns and read the label.
Spreading it evenly
Lime goes on with a drop or broadcast spreader. Check the setting printed on the bag or the spreader’s chart, since every spreader delivers a different rate at a given dial number. A quick way to calibrate is to put 10 lb in the hopper and spread a 500 sq ft test strip. At 1 lb per 20 sq ft, that strip should take 25 lb, so if the hopper empties early the dial is too high.
For a lawn that needs a large dose, split it. Spread half walking north to south and half walking east to west. The crossing passes cover the gaps, so the 50 lb on a 1,000 sq ft lawn lands more evenly. Water it in lightly afterward, and keep pets and kids off until the dust settles, especially with powdered lime.
Related pages
The lawn lime calculator lets you change the pounds per 1,000 sq ft if your soil test calls for a different rate. After liming, you may want the fertilizer calculator or the grass seed calculator.
Frequently asked questions
Should I test my soil before spreading lime?
Yes. A pH test costs a few dollars and tells you whether the soil is acidic at all. Lime on soil that is already neutral or alkaline does nothing useful and can push pH too high. Many extension offices also run lab tests that give a lime recommendation.
How much lime does a lawn need?
This calculator uses 50 lb per 1,000 sq ft, or 1 lb per 20 sq ft, a common maintenance rate. Your soil test may call for more or less, since heavy clay and sandy soil respond differently. Follow the test report when you have one.
Pelletized or powdered lime?
Pelletized lime is dust-free and spreads easily in a standard broadcast spreader. Powdered lime is cheaper per pound but blows around and can clog a spreader. The coverage rate is about the same, so choose on handling and price.
How long does lime take to work?
Slowly. Ground limestone dissolves and reacts with the soil over months, so expect a change in pH over a season rather than a week. Applying in fall lets winter rain and frost work it in.
Is garden bed lime different from lawn lime?
It is the same product, but beds are often tilled, so you can mix lime into the top 6 inches. On a lawn it sits on the surface and works down with rain. Always follow the label rate for the bag you buy.
How many bags is that?
Divide the pounds by the bag weight. The 50 lb for a 1,000 sq ft lawn is one 50 lb bag. A 5,000 sq ft yard needs 250 lb, which is five 50 lb bags.
Estimates only. Verify quantities with your supplier before purchasing.