How much fertilizer do I need for 5,000 square feet?

At 1 lb of N per 1,000 sq ft with a 26-0-3 product: (1 × 5,000 ÷ 1,000) ÷ 0.26 = 19.2 lb of product. A higher-%N bag needs fewer pounds.

What do the NPK numbers mean?

They are the percentages by weight of Nitrogen, Phosphorus and Potassium. A 26-0-3 bag is 26% N, 0% P, 3% K. Lawn feeding is planned around the N (first) number.

How do I convert pounds of nitrogen to pounds of product?

Divide the nitrogen you want by the %N as a decimal: lb of product = lb of N ÷ (%N ÷ 100). For 5 lb of N from a 26% product, 5 ÷ 0.26 = 19.2 lb.

How much nitrogen does a lawn need per year?

Roughly 2–4 lb of N per 1,000 sq ft across a season, in applications of about 1 lb at a time. Over-applying burns the lawn and runs off — a soil test tells you what it really needs.

What is the difference between fertilizer and lime?

Fertilizer supplies nutrients (N-P-K); lime raises soil pH so grass can take up those nutrients. If your soil is too acidic, use the lime calculator as well.

How much fertilizer does my lawn need? (N rate & NPK)

Lawn fertilizer is dosed by pounds of nitrogen per 1,000 sq ft, not pounds of product — and the bag tells you the %N in its NPK number. Convert with lb of product = (N rate × area ÷ 1,000) ÷ (%N ÷ 100).

By Francesco Zinghinì

What NPK means

Every fertilizer bag shows three numbers, the NPK: the percentage by weight of Nitrogen (N), Phosphorus (P) and Potassium (K). A 26-0-3 bag is 26% nitrogen, 0% phosphorus, 3% potassium. Nitrogen is what greens and grows the grass, so lawn feeding is planned around the N rate — how many pounds of actual nitrogen you put down per 1,000 sq ft.

The two-step math

You want a target amount of nitrogen, but you buy product, and the product is only part nitrogen. So:

lb of N wanted = N rate (lb per 1,000) × area ÷ 1,000
lb of product = lb of N ÷ (%N ÷ 100)

The fertilizer calculator combines both into one step from your area, N rate and the %N on your bag; the fertilizer NPK table lists pounds of product for common %N values.

Worked example: 5,000 sq ft with 26-0-3

A typical single application is 1 lb of N per 1,000 sq ft. For a 5,000 sq ft lawn with a 26-0-3 product:

Nitrogen wanted = 1 × 5,000 ÷ 1,000 = 5 lb of N.
Product = 5 ÷ 0.26 = 19.2 lb of 26-0-3.

So a bag covering 5,000 sq ft at this rate holds about 19–20 lb of product. Notice that a higher-%N product needs fewer pounds for the same nitrogen: at 46% N you would need just 10.9 lb.

How much nitrogen, how often

Most lawns want about 1 lb of N per 1,000 sq ft per application, and a total of roughly 2–4 lb per 1,000 across a growing season depending on the grass and whether you return clippings. More is not better — over-applying nitrogen burns the lawn, forces soft growth prone to disease, and runs off into waterways. Slow-release nitrogen feeds more evenly and is more forgiving than fast-release.

Phosphorus, potassium and soil tests

Phosphorus (the middle number) drives root and seedling growth — useful for a new lawn (a “starter” fertilizer), but many established lawns already have enough, and some states restrict its use to protect water quality. Potassium (the third number) supports stress and disease tolerance. The honest way to know what your lawn actually needs is a soil test from your local extension office; this calculator handles the arithmetic once you have chosen a rate, but it does not diagnose your soil.

Lime is different from fertilizer

If your soil is too acidic, grass cannot take up nutrients no matter how much you feed it — that is a job for lime, not fertilizer. Lime is applied by pounds per 1,000 sq ft too; size it with the lime calculator. And to spread any of this evenly you need to know your lawn area — measure it with the lawn-area estimator.

Quick reference: product needed at 1 lb N per 1,000 sq ft

lb of product per 1,000 sq ft = 100 ÷ %N, then scale by area:

10% N → 10 lb per 1,000 (50 lb for 5,000 sq ft).
20% N → 5 lb per 1,000 (25 lb for 5,000 sq ft).
26% N → 3.85 lb per 1,000 (19.2 lb for 5,000 sq ft).
46% N (urea) → 2.17 lb per 1,000 (10.9 lb for 5,000 sq ft).

The higher the first NPK number, the less product you spread for the same nitrogen — but a high-analysis fertilizer is also easier to over-apply and burn the lawn, so a slow-release blend at a moderate %N is more forgiving for most homeowners.

Fast-release vs. slow-release nitrogen

Two bags with the same NPK can behave very differently. Fast-release (soluble) nitrogen greens the lawn quickly but is short-lived and burns easily if over-applied or spread on a dry lawn. Slow-release (coated or organic) nitrogen feeds gradually over weeks, resists burning, and holds color longer between applications. The bag usually states what fraction of the N is slow-release; for hands-off feeding, more slow-release is better. Either way, the pound math is the same — it is the timing and burn risk that differ.

Spreading it evenly and safely

Apply in two half-rate passes at right angles for even coverage, the same two-pass method used for seed. Sweep any fertilizer off driveways and walks back onto the lawn so it does not wash into storm drains — nitrogen and phosphorus runoff is a real water-quality problem, and several states restrict phosphorus for exactly this reason. Water it in lightly after spreading unless the label says otherwise, and never apply fast-release nitrogen to a heat-stressed or dormant lawn.

Everything here is a planning estimate: follow the rate and spreader setting on your product label, and treat the typicals as a starting point, not a prescription.

Key takeaways

lb of product = (N rate × area ÷ 1,000) ÷ (%N ÷ 100); %N is the first NPK number.
A typical application is about 1 lb of nitrogen per 1,000 sq ft.
A 5,000 sq ft lawn with 26-0-3 needs about 19.2 lb of product at that rate.
Higher %N means fewer pounds — and easier to over-apply and burn; slow-release is more forgiving.
Lime raises soil pH and is a separate job; a soil test tells you what the lawn really needs.