Lawn Fertilizer Calculator
Enter your lawn size, the application rate printed on the bag, how many feedings a year, and the bag price. The calculator gives pounds per feeding, bags for the year, and the cost.
The rate comes off the bag label because it is calibrated to the nitrogen number - and nitrogen is the one that burns: more product does not mean greener, it means stripes. The holiday rhythm is the memorization trick for cool-season lawns, and the county extension soil test costs about fifteen dollars and often deletes a feeding entirely.
How to use
- Measure the lawn - guess high on the unofficial dirt patches.
- The bag label rate is printed with the N-P-K numbers.
- Memorial Day, July 4, Labor Day, Halloween - that is the rhythm.
Frequently asked questions
How much fertilizer do I need per square foot?
Bag labels rate applications in pounds per 1000 square feet - commonly 3 to 4 pounds for lawn products. The calculator scales that to your actual lawn and counts the year in bags.
How often should I fertilize my lawn?
Cool-season lawns do well on four feedings a year, memorized as the holidays: Memorial Day, July 4, Labor Day and Halloween - each landing when the grass is actually growing. Five works with irrigation; two is the honest minimum.
What happens if I use too much fertilizer?
Nitrogen burns - literal brown stripes where the spreader overlapped - plus runoff that feeds algae downstream. The label rate is a ceiling, not a suggestion; more product means stripes, not green.
Do I need a soil test before fertilizing?
The county extension soil test costs about fifteen dollars and reports what the lawn actually lacks - it often deletes a feeding entirely or swaps the product, which pays for the test the first season.