Lawn Fertilizer Calculator: How Much to Apply

How to work it out

Measure the lawn and leave out beds, paths and the house.
Find the three numbers on the bag, such as 24-0-6. The first is the percentage of nitrogen.
Choose how much nitrogen to apply. Follow the rate on the bag or from your local extension service.
Read off the amount of fertilizer, then set your spreader using the settings on the bag.

Fertilizer for 1 lb of nitrogen per 1,000 sq ft

Nitrogen in the bag	Fertilizer needed
10%	10 lb
16%	6.25 lb
20%	5 lb
24%	4.17 lb
29%	3.45 lb
32%	3.13 lb

These are common starting points. Your site, climate and supplier may call for something different.

What the three numbers mean

They are the percentages by weight of nitrogen, phosphorus and potassium, in that order. A 50 lb bag of 24-0-6 holds 12 lb of nitrogen.

Follow the label and local rules

Lawn needs vary with grass type, season and climate, and too much nitrogen can burn grass and wash into waterways. Some states and towns limit when or what you can apply. Treat the rate here as a starting point and check the bag and your local extension service.

Common questions

How much 24-0-6 do I need for 1 lb of nitrogen per 1,000 sq ft?

About 4.17 lb per 1,000 sq ft, because 1 ÷ 0.24 = 4.17. For a 5,000 sq ft lawn that is about 21 lb.

How much nitrogen should I put on my lawn?

Many lawn guides suggest around 1 lb of nitrogen per 1,000 sq ft in a single application, but the right amount depends on your grass and climate. Follow the bag and your local extension service.

What do the numbers on a fertilizer bag mean?

They show nitrogen, phosphorus and potassium as a percentage of the bag's weight. The first number is the one this calculator uses.

How do I convert per 1,000 sq ft to per acre?

Multiply by 43.56, because an acre is 43,560 sq ft.

Doing this job for a customer? Turn your numbers into a free written estimate on QuoteToPaid.

Lawn fertilizer calculator