Reviewed June 18, 2026
Free lawn fertilizer calculator
Calculate how many pounds of fertilizer to apply from your lawn size, target nitrogen rate, and the nitrogen percentage printed on the bag.
15.63lb product
2.5 lb of that is actual nitrogen (the bag is 16% N)
Total for 5,000 sq ft
3.13 lb product per 1,000 sq ft
Spread half in one direction and half at 90 degrees for even coverage. Always follow the bag's labeled rate limits.
01The core fertilizer formula
Purdue Turfgrass explains the basic two-step math: divide the desired pounds of nutrient per 1,000 square feet by the nutrient percentage, then multiply by the treated area. For example, a 0.75 lb nitrogen target with a 16% nitrogen product needs 0.75 ÷ 0.16 = 4.69 lb of product per 1,000 square feet.
02Why a calculator beats guessing
- It separates actual nitrogen from product weight.
- It scales the rate to your real lawn square footage.
- It helps avoid accidental over-application when switching products.
- It creates a log so you know what was applied and when.
03Use Lawn Dominator
Use Lawn Dominator to calculate treatment amounts, save the product, log the date and rate, and compare results with photos over the season.
Do this automatically in the app
Free to download on iPhone and Android.
Research and extension sources
UPDATED 2026-06-18