Lawn Fertilizer Calculator

About Lawn Fertilizer Calculator

The Lawn Fertilizer Calculator converts a turfgrass nitrogen recommendation into the amount of fertilizer product to apply. Enter your lawn area, the recommended pounds of nitrogen per 1,000 square feet, and the N-P-K analysis from the fertilizer bag. The calculator returns product weight, nitrogen supplied, product rate per 1,000 square feet, optional bag coverage, and the phosphate and potash applied at the same time.

Lawn Fertilizer Formula

For a 5,000 sq ft lawn at 1 lb nitrogen per 1,000 sq ft, the target is 5 lb of actual nitrogen. If the fertilizer is 25-0-5, nitrogen is 25% of the product, so the product amount is 5 ÷ 0.25 = 20 lb of fertilizer.

How to Use the Lawn Fertilizer Calculator

1. Enter lawn area: Use the turf area that will actually receive fertilizer, not the full lot size.
2. Enter the nitrogen rate: Use the recommended pounds of nitrogen per 1,000 square feet from your turf plan, soil test, product program, or local extension guide.
3. Enter the N-P-K analysis: Type the three percentages on the bag, such as 24-0-6 or 30-0-4.
4. Add bag weight if useful: The optional bag weight estimates how many bags to buy and how much lawn one bag covers.
5. Review co-applied nutrients: Check phosphorus and potassium amounts before spreading, especially where local rules restrict phosphorus.

What the Lawn Fertilizer Inputs Mean

Practical Lawn Application Notes

Frequently Asked Questions

How much fertilizer do I need for my lawn?

Use this formula: lawn area in thousands of square feet multiplied by the target nitrogen rate, divided by the nitrogen percentage on the bag. For example, 5,000 sq ft at 1 lb N per 1,000 sq ft needs 5 lb of nitrogen; a 25-0-5 fertilizer is 25% nitrogen, so it takes 20 lb of product.

What does the nitrogen rate per 1,000 sq ft mean?

It is the amount of actual nitrogen, not fertilizer product, recommended for each 1,000 square feet of lawn. The calculator converts that nutrient target into product weight using the N number in the N-P-K label.

Can I use square meters or acres?

Yes. The calculator converts square meters and acres into square feet internally, then applies the nitrogen rate per 1,000 square feet.

Why does a lower nitrogen percentage require more fertilizer?

A lower N number means each pound of product contains less nitrogen. To supply the same nitrogen target, you need more total product from a 10-0-10 fertilizer than from a 25-0-5 fertilizer.

Does this replace the fertilizer label or a soil test?

No. This calculator converts a known nitrogen recommendation into a product amount. Always follow the fertilizer label, local restrictions, and soil test or turfgrass guidance.