Lawn Fertilizer Calculator
How many pounds of product your lawn needs.
Enter your values
Enter the lawn size in sq ft.
Enter the nitrogen in the bag in %.
Enter the target nitrogen rate in lb per 1000 sq ft.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Fertiliser needed
- 20.83 lb
- Per 1,000 sq ft
- 4.17 lb
- Nitrogen applied
- 5 lb
- 50 lb bags needed
- 0.42
Quick answer
Pounds of product = target lb of nitrogen per 1,000 sq ft × lawn area ÷ 1,000 ÷ the nitrogen percentage.
lb product = (N rate × area ÷ 1000) ÷ (N% ÷ 100)
At a glance
| What it does | How many pounds of product your lawn needs. |
|---|---|
| Category | Home & DIY |
| Inputs needed | Lawn size, Nitrogen in the bag, Target nitrogen rate |
| Main output | Fertiliser needed |
| Formula | lb product = (N rate × area ÷ 1000) ÷ (N% ÷ 100) |
| Cost | Free — no sign-up, no download |
How to use the Lawn Fertilizer Calculator
- 1Measure your lawn area in square feet.
- 2Read the first number of the NPK analysis on the bag.
- 3Set your target nitrogen rate.
Inputs explained
- Lawn size(sq ft)
- Enter the lawn size in sq ft.
- Nitrogen in the bag(%)
- Enter the nitrogen in the bag in %.
- Target nitrogen rate(lb per 1000 sq ft)
- Enter the target nitrogen rate in lb per 1000 sq ft.
Worked example
Using the values the calculator loads with:
Inputs
- Lawn size5000 sq ft
- Nitrogen in the bag24 %
- Target nitrogen rate1 lb per 1000 sq ft
Results
- Fertiliser needed20.83 lb
- Per 1,000 sq ft4.17 lb
- Nitrogen applied5 lb
- 50 lb bags needed0.42
Frequently asked questions
What is a typical nitrogen rate?
1 lb of nitrogen per 1,000 sq ft per application, with 3–4 lb total per year for cool-season grass.
What do the three NPK numbers mean?
Percentages by weight of nitrogen, phosphorus and potassium — 24-0-6 means 24% nitrogen and no phosphorus.
What do I need to enter into the Lawn Fertilizer Calculator?
Just 3 values: lawn size, nitrogen in the bag, target nitrogen rate. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Lawn Fertilizer Calculator work out the answer?
Pounds of product = target lb of nitrogen per 1,000 sq ft × lawn area ÷ 1,000 ÷ the nitrogen percentage. It applies the formula lb product = (N rate × area ÷ 1000) ÷ (N% ÷ 100) and shows the working so you can check each step by hand.
Is the Lawn Fertilizer Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.