- Add the square feet of your lawn
- Add the total pounds of Nitrogen you wish to apply per 1,000 ft²
- (Note, this calculator can also be used for both Phosphorus and Potassium)
- Add the Nitrogen percentage located on your bag of fertilizer
- eg: 6-4-0 for Milorganite (Add 6)
- Click “Calculate
More Lawn Care Calculators
- Azoxystrobin Calculator
- Tenacity Herbicide Calculator
- Liquid Nitrogen Calculator
- Nitrogen Calculator
- Dimension Calculator (Pre-Emergent Herbicide)
- Prodiamine Calculator (Pre-Emergent Herbicide)
Proper Nitrogen, Phosphorus and Potassium fertilizer applications on your lawn are crucial to year-long success of your turf. Add too much nitrogen at the wrong time, and your lawn could burn. Add too little over the course of a year, and signs of your underfed turf – not thick, green or healthy looking – will show.
A good rule of thumb is to apply four (4) pounds of nitrogen fertilizer to your lawn every year. Depending on the number of times you apply lawn fertilizer throughout the year will dictate how much nitrogen needs to be applied with each feeding.
The same goes for the other essential macronutrients – Phosphorus and Potassium. A good maintenance lawn fertilizer will include a 3-1-2 or 4-1-2 ratio; the first three numbers located on the fertilizer bag (Nitrogen – Phosphorus – Potassium).
If you’re using a 4 Step plan, then aiming for approximately one pound of nitrogen per 1,000 ft² is the goal. But if you choose to spoon feed more frequently, then anywhere between 0.25 and 0.5 pounds of nitrogen per 1,000 ft² per fertilizer application is ideal.
So how do you know how much nitrogen, phosphorus and potassium fertilizer you’re applying? You can use our nitrogen calculator to determine how much nitrogen is in each bag of the fertilizer of choice.
Next, find the square footage of your lawn. One of my favorites is from Sod Solutions.
Then, use this lawn fertilizer calculator. Plug in your lawn square footage, desired amount of nitrogen to be delivered per 1,000 ft², and the nitrogen percentage on the bag of your lawn fertilizer.
How to calculate lawn fertilizer per 1,000 ft²
- Nitrogen percentage ÷ 100 (e.g. Milorganite “6” = 0.06)
else total = b / ( c / 100 ) * a / 1000;
The formula looks like this… if I want to apply 1 lbs. of Nitrogen on my 5,000 ft² lawn and using Milorganite fertilizer as a guide:
Desired Nitrogen weight ÷ (Nitrogen percentage ÷ 100) x your lawn’s square footage ÷ 1,000
1 ÷ (6 ÷ 100) x 5,000 ÷ 1,000 = 83.3 lbs. of total Milorganite fertilizer to cover my 5,000 ft² lawn – or about 2.5 total bags of the 32 lbs. Milorganite nitrogen fertilizer.
I hope this lawn fertilizer calculator is helpful! Please let me know by commenting below.
If you have any questions or see any bugs in this lawn fertilizer calculator, please contact me.