Lawn Fertilizer Calculator
Enter the lawn, the nitrogen rate and the bag, and get the pounds of product and the bags to load for one application.
Fertilizer calculator: pounds of product and bags by lawn size
Lawn area
Enter the turf you will spread, with the house, drive and beds already taken out. One acre is 43,560 sq ft.
The product
Enter the lawn’s area above to see the pounds of product for one application.
Size the load on the whole parcel and you buy product for the roof and the drive. Trace the turf on satellite imagery and load the spreader for the lawn itself.
Rates from Purdue and Clemson Extension, checked 29 October 2026. Follow the product label and your state's rules.
How Much Fertilizer per 1,000 Sq Ft
Lawn rates are set in pounds of nitrogen, so the bag's first number does the work:
lb of product per 1,000 sq ft = lb of N ÷ (N% ÷ 100)
Purdue's worked lawn: 5,500 sq ft of 18-0-10 at 0.5 lb of N. That is 2.78 lb per 1,000 sq ft and 15.3 lb for the lawn. At 1.0 lb of N, the calculator's starting rate, the same lawn takes 30.6 lb.
Nitrogen by Grass Type, per Year
Split the year's total into applications of 0.5 to 1.0 lb. In Clemson's table the low end is a low-maintenance program and the high end a high-maintenance one; Purdue splits its rows by maintenance level.
| Grass | Lb N per 1,000 sq ft |
|---|---|
| Bermudagrass | 3 to 5 |
| Zoysiagrass | 3 to 5 |
| St. Augustinegrass | 1 to 4 |
| Centipedegrass | 1 to 2 |
| Tall fescue / Kentucky bluegrass | 1 to 3 |
| Program | Lb N per 1,000 sq ft |
|---|---|
| Lowest maintenance | 1 to 3 |
| Moderate | 2 to 4 |
| Moderate, irrigated | 2 to 4 |
| Highest, irrigated | 3 to 5 |
Per-Application Limits
- Per application. Purdue advises no more than 1.0 lb of quick-release nitrogen per 1,000 sq ft at once, 2.0 lb when most of it is slow-release.
- Phosphorus. Minnesota bans it on turf unless a soil test shows a need, the lawn is new seed or sod in its first season, or it is a golf course.
- Nitrogen by law. The 0.7 lb limit New Jersey set for professionals in 2011 is on water-soluble nitrogen per 1,000 sq ft in one application. The same law caps total nitrogen at 1 lb an application and 4.25 lb a year, and bars nitrogen or phosphorus on turf from December 1 to March 1. That is the law as enacted in 2011; check the state's current rules before the season.
Rules differ by state and town, and many states license whoever applies fertilizer or weed control for hire; see how to start a lawn care business for examples.
Pricing the Application
A fertilization visit sells for $0.02 to $0.08 a sq ft per application, product and labor together, and Lawn Love's cheapest typical visit is $64. Your number is the product the calculator weighs out at your cost per pound, plus your time on site and the drive, with your margin on top. The calculator shows the range for the lawn you enter.
The Rate Is per 1,000 Sq Ft, So the Area Is the Dose
Over-measure a lawn and you over-apply on every round all year; under-measure it and you price the program too low.
In SurfaceMeasure's Lawn mode you search the address, trace the lawn, cut out the house, drive and beds, and pick Fertilization on the result card for the market range before you price the round. Or work it by hand with the lawn square footage calculator.
Fertilizer Questions
Calibrating, timing, the form and the bag.
Don't trust the setting on the bag: Penn State says a recommended setting should not be trusted to deliver the rate. Load a known weight, run a measured strip (Clemson uses 50 or 100 ft), and weigh what's left. The strip should take the rate per 1,000 sq ft × the swath width × the strip length ÷ 1,000. Adjust and repeat until it does. For even coverage, Penn State sets the spreader to half the rate and covers the lawn twice.
It depends on the grass. Purdue puts most of a cool-season lawn's nitrogen from late summer through autumn, up to 1.0 lb a month from late August to early November, less in the spring flush, little to none in summer, and none on frozen ground. Clemson starts warm-season lawns once the grass has greened up and is growing, and its bermudagrass calendar puts the last nitrogen before August 15.
Choose by the nitrogen source. Purdue: quick-release nitrogen is generally cheaper, dissolves for liquid applications and is likelier to burn the leaf, so water it in; most slow-release sources can't be mixed with water. For small lawns hemmed in by walks and drives, Penn State suggests a drop spreader or a liquid application for accuracy.
The percent by weight of nitrogen, phosphate and potash, in that order. A 100 lb bag of 16-4-8 holds 16 lb of nitrogen, 4 lb of phosphate and 8 lb of potash. The calculator only needs the first number, because lawn rates are set by the nitrogen.
Read the bag: coverage depends on its weight and analysis. The University of Missouri notes most lawn products are sized to cover 5,000 or 7,500 sq ft. Enter the bag's weight in the calculator and it counts the bags for your lawn at your rate.
Sources
Checked 29 October 2026. Your state's extension service has the rates for your grass and soil.
- Purdue Extension AY-22-W: Fertilizing Established Cool-season LawnsThe formula and worked lawn, per-application rates and caps, annual N, timing, nitrogen sources. August 2013.
- Clemson Cooperative Extension HGIC 1201: Fertilizing LawnsWhat the bag's numbers mean, annual N by grass. Revised October 2019.
- University of Missouri: Lawn Fertilizer CalculatorThe coverage most lawn bags are sized for.
- Minnesota Statutes 18C.60: Phosphorus Turf Fertilizer Use RestrictionsPhosphorus on turf, subdivision 2.
- New Jersey P.L.2010, c.112 (fertilizer application standards)Professional nitrogen limits and closed dates, as enacted January 2011.
- Penn State Extension: Calibrating Your Fertilizer SpreaderCalibrating a spreader; half rate, two passes. Updated April 2025.
- Clemson Cooperative Extension HGIC 1657: Calibrating SpreadersThe test strip and its formula. Revised July 2019.
- Penn State Extension: Turfgrass Fertilization, A Basic Guide for Professional Turfgrass ManagersDrop spreader or liquid on small, enclosed lawns. Updated November 2016.
- Clemson Cooperative Extension HGIC 1216: Bermudagrass Yearly Maintenance ProgramThe last nitrogen for bermudagrass. Revised November 2018.
- LawnStarter: How Much Does Lawn Fertilization CostThe price of an application per sq ft, the band the tool's Lawn card shows.
More for Lawn Care Companies
Price the Whole Program From One Measurement
Search the address, trace the turf, check the range for mowing, fertilization, aeration or sod, and send a branded quote. Card required, cancel anytime.