SettingsSettings for this calculationUS
Area to be treated.
Measure the grass only — beds, paths and the drive are not lawn and fertilising them wastes product and feeds weeds.
The first number in the N-P-K on the bag.
A 20-5-10 product is 20% nitrogen. That first figure is what sets the application rate — two products with very different bag weights can deliver identical nitrogen.
Nitrogen to apply per 100 m².
0.35 kg per 100 m² is about 0.7 lb per 1000 sq ft, a standard single application for cool-season grass. Exceeding roughly 0.5 kg per 100 m² in one dose risks scorch, particularly with a fast-release product in warm weather.
Product required
7.71 lb of product
Delivers the stated nitrogen rate. Whether that rate suits your grass depends on species, season and soil test — nitrogen is the one nutrient it is easy to over-apply visibly.
- Nitrogen delivered
- 1.54 lb n
- Product in pounds
- 7.71 lb
- Rate per 100 m²
- 1.75 kg/100 m²
- Rate per 1000 sq ft
- 3.58 lb/1000 sq ft
They open the calculator with your figures already in it
Lawn Fertiliser Calculator: 7.71 lb of product — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Typical cool-season lawn nitrogen rate: 25-50 kg N per hectare per application (0.5-1.0 lb N per 1000 sq ft) — university turf extension guidance
- Product application rate = target N rate ÷ (N percentage ÷ 100)
Inputs used
- Lawn area
- 2150 sq ft
- Nitrogen in the product (%)
- 20
- Target nitrogen (kg N per 100 m²)
- 0.35
Intermediate steps
- Nitrogen delivered
- 1.54 lb n
- Product in pounds
- 7.71 lb
- Rate per 100 m²
- 1.75 kg/100 m²
- Rate per 1000 sq ft
- 3.58 lb/1000 sq ft
Confidence note: Delivers the stated nitrogen rate. Whether that rate suits your grass depends on species, season and soil test — nitrogen is the one nutrient it is easy to over-apply visibly.
What this calculation does not cover
- No soil test is assumed. Phosphorus and potassium should follow a test rather than a blanket rate, and in several jurisdictions phosphorus application to established lawn is restricted.
- Warm-season and cool-season grasses want nitrogen at opposite times of year.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-08-26 · in the site-wide review of 2026-09-06 · v1.0.0
Regulatory standards & verification citations2
- Typical cool-season lawn nitrogen rate: 25-50 kg N per hectare per application (0.5-1.0 lb N per 1000 sq ft) — university turf extension guidance
- Product application rate = target N rate ÷ (N percentage ÷ 100)
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