Lawn Lime Calculator
Calculate how much lime your lawn needs, based on area and soil type, so you buy the right number of bags.
How to use the lawn lime calculator
- Enter the lawn area in square meters.
- Choose soil type — clay soil is often more acidic and needs more lime than sandy soil.
- The calculator shows how much lime you need in total, and how many 25 kg bags to buy.
How the lime amount is calculated
The calculator multiplies the lawn area by the recommended lime amount per square meter for the selected soil type:
For a 150 m² lawn with normal soil (150 g/m²), you need 150 × 150 = 22,500 g, i.e. 22.5 kg of lime — equivalent to 1 bag of 25 kg.
Liming adjusts the soil's pH level, making nutrients more available to the grass and giving healthier, denser growth. Clay soil is often naturally more acidic than sandy soil, and therefore needs more lime to reach the same pH level.
Why liming can look like fertilising
Lime supplies almost no nutrients itself. The effect is indirect: acidic soil chemically locks up nutrients that are already present in forms plants cannot access. When lime raises the pH, those nutrients are released. A limed lawn can therefore look as though it has been fertilised even though not a single gram of nitrogen has been added.
That is also why liming and fertilising should not be done on the same day. Lime reacts with nitrogen fertiliser and can drive off part of the nitrogen as ammonia before the plants take it up. Common practice is to separate the two operations by a few weeks, and to take a soil test before liming at all — if the pH is already where it should be, more lime does nothing.
Frequently asked questions
When during the year should I lime my lawn?
Spring and fall are the best times for liming. Avoid liming during dry spells or right before heavy rain, since much of the lime can wash away before it has a chance to work.
Why does clay soil need more lime than sandy soil?
Clay soil often has a more acidic natural pH and greater buffering capacity, meaning more lime is required to noticeably raise the pH compared to lighter sandy soil.
Can I lime too much?
Yes. Too high a pH can make certain nutrients less available to the grass and favor weeds. Follow the recommended amount, and consider taking a soil test before liming repeatedly year after year.