Loam & Level

Lawn fertilizer calculator

Enter your lawn size, the first number on the fertilizer bag, and how much nitrogen you want to apply. You'll get the pounds of fertilizer to spread and how many bags to buy.

–pounds of fertilizer
Lawn area (sq ft)
–
Per 1,000 sq ft (lb)
–
Bags to buy
–

One pound of nitrogen per 1,000 sq ft is a common single application. Follow the bag label if it says less.

Reading the numbers on a fertilizer bag

The three numbers, such as 24-0-6, are the percent of nitrogen, phosphorus and potassium by weight. A 15 pound bag of 24-0-6 contains 3.6 pounds of nitrogen. Lawns use nitrogen most, which is why it's the number this calculator uses.

How the math works

Divide the nitrogen you want by the nitrogen percent to get pounds of product per 1,000 square feet, then scale it to your lawn. For 1 pound of nitrogen from a 24% product, that's about 4.2 pounds per 1,000 square feet. A 5,000 square foot lawn needs about 21 pounds.

How much nitrogen per year?

Many lawns do well with 2 to 4 pounds of nitrogen per 1,000 square feet per year, split into several feedings. Low-maintenance grasses and lawns where clippings are left on the grass need less. A soil test from your local extension service tells you what your lawn actually lacks.

Common questions

When should I fertilize?

Cool-season grasses benefit most from feeding in fall, with a lighter feeding in spring. Warm-season grasses are fed while they're actively growing, from late spring through summer.

What happens if I use too much?

Too much quick-release nitrogen can burn grass, and the excess washes into storm drains and streams. Sweep any granules off driveways and sidewalks after spreading.

How do I set my spreader?

Spreader settings depend on the brand and the product, so check the setting chart on the bag. To spread evenly, apply half the amount in one direction and the other half at a right angle.

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