Fertilizer Calculator

Maryland's Fertilizer Use Act of 2011 regulates the amount of fertilizer that can be applied to home lawns. This was done to prevent over application of fertilizer from harming both lawns and the bay. Follow the steps below to calculate exactly how much fertilizer you can apply to your lawn and still stay within the requirements outlined in the legislation.

Step 1: Enter your lawn square footage.


Not sure? Use our area calculator and then come back to this page.

Step 2: Enter the nitrogen percentage from your fertilizer bag


There are a set of 3 numbers found on every bag of fertilizer. Examples: 10 - 10 - 10, 20 - 0 - 10

Enter just the first number, which is the percentage by weight of nitrogen. Example: Enter 20 for 20 - 0 - 10 fertilizer

Step 3: Is the fertilizer labeled as slow-release or extended release?

Maryland Law allows more fertilizer to be applied if some of the nitrogen is not soluble. Check your bag to see if it is at least 20% slow-release.