Free tool from LawnzoLawn fertilizer calculator
Enter the three numbers on the bag, your lawn size and the rate of nitrogen you want. You get the pounds of product per 1,000 sq ft, the total, and how many bags to buy.
This product has no nitrogen: enter its first number, or pick a product that has some.
Enter the lawn area.
{total} lb for the whole lawn ({area} sq ft).
{count} bag of {weight} lb (you use {percent}%)
{count} bags of {weight} lb (you use {percent}%)
Enter the bag weight
Spread per 1,000 sq ft
4.17 lb
20.8 lb for the whole lawn (5,000 sq ft).
- Bags to buy
- 1 (you use 42% of it)
- Nitrogen applied
- 5 lb
- Phosphate (P₂O₅) applied
- 0 lb
- Potash (K₂O) applied
- 2.08 lb
Check the label: its rate and spreader setting come first. Split the total across two passes at right angles for even cover.
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Lawn care calendar by state
- AlabamaFeed Alabama warm-season lawns from April or May through August; seed tall fescue in September and October.
- ArizonaOverseed bermudagrass with ryegrass in October, and feed it half a pound of nitrogen a month while it grows.
- ArkansasFeed bermudagrass from late May to September, feed tall fescue in March, mid-September and November, and seed in May and June or September and October.
- CaliforniaWarm-season lawns are fed from April to September, and tall fescue in spring and fall.
- ColoradoFeed Colorado bluegrass in spring, mid-August to mid-September and early October to early November.
- ConnecticutSeed Connecticut lawns from August 15 to mid-September and feed from September to October 15.
- FloridaFertilize only during the growing season, and finish by late September in the north.
- GeorgiaFeed warm-season grasses from May through August, and tall fescue in February-March and October-November.
- IdahoFeed in early May, June, early September and late October, seed from mid-August to mid-September, and water by soil type.
- IllinoisFertilize and seed Illinois lawns in late summer, with a lighter feeding in spring.
- IndianaSeptember and November are the two best times to fertilize a lawn in Indiana, and seeding peaks August 15 to September 15.
- IowaFertilize Iowa lawns in spring, mid-September and late October, and seed from mid-August to mid-September.
- KansasFeed cool-season lawns in September and November and warm-season lawns from May to August; seed tall fescue in September.
- KentuckySeed Kentucky lawns from mid-August to late September and feed from October through the fall.
- LouisianaFeed Louisiana lawns through the growing season, then swap to potash in September.
- MarylandFertilize tall fescue from September to November 15, seed by mid-October, and keep fertilizer off the lawn before March 1.
- MassachusettsThe late-summer feeding near Labor Day matters most, and fertilizer is barred on frozen, snow-covered or dormant turf.
- MichiganFall is the best time to seed a Michigan lawn, and spring crabgrass control runs by soil temperature, not the calendar.
- MinnesotaSeed and feed Minnesota lawns from early August to mid-October, with a lighter feeding in May and June.
- MississippiFeed hybrid bermudagrass from April 1 on the coast and from May 15 in the north, and plant it between spring and midsummer.
- MissouriFall feeding in September is the one to keep, and seeding runs from August 25 to October 10.
- NebraskaFeed Nebraska cool-season lawns in late April or May, early June, late August to mid September and mid-October, and overseed in mid-August to mid-September.
- NevadaMow at 3 inches, feed by late September, aerate once a year, and water on your assigned days.
- New JerseySeed from mid-August to early October, and fertilize only between March 1 and November 15.
- New MexicoSeed cool-season grass from mid-August to mid-October and warm-season grass from late April or mid-May to August, depending on where you live.
- New YorkFeed in September, seed from mid-August through September, and stop by December 1.
- North CarolinaSeed cool-season grass from mid-August to October 1, and warm-season grass from March 1 to July 1.
- OhioFertilize Ohio lawns in April and May and again in September and October.
- OklahomaFeed Oklahoma bermudagrass from April to September 15, and tall fescue in March, May, October and November.
- OregonSeed Oregon lawns from mid-August to mid-September and feed four times a year.
- PennsylvaniaSeed in late summer to early fall, and feed in spring and again in late summer.
- South CarolinaFeed South Carolina warm-season lawns in May after full green-up, again in summer, and finish by August 15.
- TennesseeTall fescue is seeded in late summer, and warm-season lawns get their main feeding around May.
- TexasFeed once the grass is growing, and make the last nitrogen application 4 to 6 weeks before the first frost.
- UtahSeed Utah lawns in late summer, feed in May, September and November, and water by the interval, not the date.
- VirginiaFeed cool-season lawns from mid-August to early November, and warm-season lawns from April 1 to August 15.
- WashingtonFeed four times a year, with 1 pound of nitrogen each time, and seed in April and May or early fall.
- West VirginiaFeed in March and April, June and July, and October and November, with the heaviest feeding in fall; seed in early to mid September.
- WisconsinSeed from late August into early September, and feed once on September 1 to 15 with about 1 pound of nitrogen.
How it works
Lawn recommendations are given in pounds of nitrogen (N) per 1,000 square feet, but you spread product, not nitrogen. The first number on the bag is the percentage of nitrogen by weight, so you divide the rate you want by that percentage.
Example from Iowa State University Extension: to apply 1 lb of N per 1,000 sq ft with a 32-0-4 fertilizer, spread 1 ÷ 0.32 = 3.125 lb of product per 1,000 sq ft. On a 5,625 sq ft lawn that is 3.125 × 5,625 ÷ 1,000 = 17.58 lb.
The same product also carries phosphate (P₂O₅) and potash (K₂O) in the proportion of its second and third numbers; the tool shows how much of each you apply.
Product per 1,000 sq ft = N rate ÷ (N% ÷ 100). Total = product per 1,000 sq ft × lawn area ÷ 1,000.
Good to know
- The right nitrogen rate depends on your grass, your region and the season. A soil test or your state extension office gives the best number.
- Read the bag: its label rate and spreader settings come first, and some states limit phosphorus on lawns.
- Keep fertilizer off driveways and sidewalks, and sweep it back onto the grass.
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<p style="margin:4px 0 0;font-size:14px"><a href="https://lucernel.com/tools/lawn-fertilizer-calculator">Lawn fertilizer calculator by Lawnzo</a></p>Frequently asked questions
How much fertilizer do I need for 1,000 square feet?
Divide the pounds of nitrogen you want by the nitrogen percentage on the bag. For 1 lb of N with a 24-0-10 product: 1 ÷ 0.24 = 4.17 lb of product per 1,000 sq ft.
What do the three numbers on a fertilizer bag mean?
Nitrogen, phosphate (P₂O₅) and potash (K₂O), each as a percentage of the bag weight. A 50 lb bag of 24-0-10 holds 12 lb of nitrogen.
How do I measure my lawn?
Split it into rectangles, multiply length by width for each one, and add them up. Leave out the house, driveway and flower beds.
Sources
- Iowa State University Extension: How to calculate fertilizer rates for the lawn
- University of Missouri Extension: Calculating fertilizer rates
Checked on September 26, 2026.
For the rest, there is Lawnzo
Lawnzo tells you when, not only how much.
Lawnzo builds a season plan for each lawn: when to fertilize, mow, seed and water, checked against the forecast, with a journal of what you did.
- Seasonal plans for your grass type
- Weather checks that keep, delay or skip a task
- A journal of products, quantities and photos
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