Fertilizer Rate Calculator

Calculate fertilizer application rate for gardens, raised beds, flower beds, lawns, and growing areas. Estimate pounds per 100 square feet, pounds per 1,000 square feet, pounds per acre, nitrogen rate, fertilizer amount, bags needed, and application cost.

Calculate Fertilizer Rate

Fertilizer Needed = Area × Application Rate. Rate = Fertilizer Amount ÷ Area.
Your result will appear here.

How the fertilizer rate calculator works

Amount from rate mode:
The calculator uses area and application rate to estimate total fertilizer needed.

Rate from amount mode:
The calculator uses a known fertilizer amount and area to calculate the equivalent rate per 100 square feet, per 1,000 square feet, and per acre.

Nitrogen rate mode:
The calculator converts a target nitrogen rate into a fertilizer application rate using the nitrogen percentage on the fertilizer label.

Bags from rate mode:
The calculator estimates how many bags are needed from area, application rate, bag weight, and extra material.

Why use a fertilizer rate calculator?

A fertilizer rate calculator helps convert application recommendations into practical fertilizer amounts for a specific garden or lawn area.

It can help compare fertilizer rates, avoid over-application, calculate nitrogen-based applications, estimate bags to buy, and plan seasonal fertilizer costs.

What your result means

Your result shows fertilizer needed, rate per 100 square feet, rate per 1,000 square feet, rate per acre, nitrogen supplied, bags needed, purchase cost, seasonal amount, and seasonal cost.

Fertilizer rate formulas

Frequently asked questions

How do I calculate fertilizer rate?

Divide fertilizer amount by the area, then convert the result to the rate unit you need, such as pounds per 100 square feet or pounds per 1,000 square feet.

How do I calculate fertilizer needed from a rate?

Multiply the application rate by the area. For example, a rate per 100 square feet is multiplied by area divided by 100.

How do I calculate fertilizer from a nitrogen rate?

First calculate the total pounds of nitrogen needed, then divide by the fertilizer nitrogen percentage as a decimal.

How many square feet are in an acre?

One acre equals 43,560 square feet.

Is this fertilizer rate calculator exact?

No. This is an estimate. Actual fertilizer rates should be based on soil tests, crop needs, fertilizer type, local recommendations, irrigation, weather, and growing conditions.