Lime Calculator

How much lime your lawn needs, in pounds and in bags, without a soil test. Tell it your lawn size, your soil, and what the lawn is doing, and it works out a rate that will be about right for most lawns.

About this tool: how much lime does a lawn need?

    About this tool: how much lime does a lawn need?

    What lime does

    Raises soil pH, nothing else. Grass wants 6.0 to 7.0. If your pH is fine, lime can only hurt.

    Why lawns go acidic

    Rain leaches out calcium and magnesium, and nitrogen fertilizer acidifies directly. Pine needles are largely innocent.

    How much per 1,000 square feet

    Depends how far pH must move and how hard your soil resists. To raise it one full point:

    Soil typeLime per 1,000 sq ft
    Sandy / light25 to 35 lb
    Sandy loam40 to 50 lb
    Loam (typical topsoil)55 to 70 lb
    Clay loam70 to 80 lb
    Heavy clay85 to 100 lb

    Extension mid-ranges (Penn State, NC State, UMass). Never more than 50 lb at once; the calculator splits anything larger into passes six months apart.

    Without a soil test

    This estimates your starting pH from what the lawn is showing. A lab measures reserve acidity, which sets the real requirement and is invisible from the surface. Tests are $15 to $20 through county extension. Under-liming costs a second pass; over-liming costs a year.

    Centipedegrass is the exception

    It wants 5.0 to 6.0 and declines at the 6.5 that suits fescue. Soil test first.

    Which lime to buy

    • Pelletized: clean to spread. Buy this.
    • Pulverized: same rock, same weight, cheaper, dusty.
    • Dolomitic: adds magnesium, about 10% less by weight. Not every year.
    • "Fast-acting" prills: quicker, far pricier per pound of neutralizing power. Follow the bag.

    CCE

    The only number that changes how much you need. This tool assumes 95% calcitic, 105% dolomitic; scale by 95 divided by your bag's figure.

    ProductTypical CCEEffect on the amount
    Calcitic limestone (pelletized or pulverized)85 to 100%Baseline
    Dolomitic limestone95 to 109%About 10% less by weight

    Applying it

    Two passes at right angles, half rate each, then water in. Keep two weeks clear of fertilizer. Autumn is best; three to six months before pH moves.

    When not to lime

    • pH is not confirmed as the problem. Compaction, shade and grubs are more common.
    • You are in an arid or limestone region.
    • You limed within the last year.
    • You saw moss, which means shade and damp, not acidity.