Fertilizer Calculator Online (NPK Application Rate)

I hope this fertilizer calculator will make things easier for you; feel free to use it whenever you want to. I recommend you bookmark this page.

How to Use the Lawn Fertilizer Calculator?

The first thing you need to do is input the number of square feet. For example, go ahead and input 1000.

Next, you place your nitrogen, phosphorus, and potassium rate. For example, you can set it up for 30-10-10.

Then you need to set up how many pounds per square feet. In this example, let’s go with the industry standard of 1 pound per 1000 sq ft.

And you’re done. The result should be 3.3 pounds of fertilizer needed to cover 1000 square feet.

Fertilizer Calculator Formula (NPK Application Rate)

Besides using this fertilizer calculator, I also recommend you learn how to get the application rate without the calculator. 

This will give you more flexibility if, for some reason, you don’t have it available. 

For example:

Let’s say you have a 30-10-10 fertilizer which you’re looking to apply to a 1000 sq ft lawn. 

You will use the industry-standard application rate of 1 pound per 1000 thousand square feet.

Also, convert the nitrogen percentage into a decimal.  

So the formula should look like this. 

(1 lb of fertilizer x 1000 square feet) ÷ 0.30 = 3.3 pounds of 30-10-10 fertilizer is needed to cover 1000 square feet of your lawn. 

How Much Fertilizer per Acre?

So to get the application rate per acre, if we follow the previous example results. All you have to do is the following. 

3.3 lb of fertilizer x 1 acre (1 acre = 43560 square feet) = 143,748 ÷ 1000 sq ft = 143 pound of 30-10-10 fertilizer is needed to cover 1 acre.

More About the NPK Fertilizer Calculator

Remember, the calculator is based on an average industry-standard formula, so it’s not perfect, but it can definitely help you do you with your fertilizer application rate. 

I will be performing updates to this calculator, so you should see an update in the next few weeks. And will try to keep it as simple as possible.