Can't find the exact fertilizer analysis that was custom selected for your gardening situation in your MSU Soil Test website fertilizer recommendation? This calculator can be used to determine how much nitrogen (N), phosphorus (P2O5), and potassium (K2O) (in lbs./1000 ft.²) the fertilizer analysis you choose will supply. If your fertilizer recommendations are in lbs/100 sq ft, you will need to divide the result you get by 10.
All fertilizers have three numbers on the label which indicate the fertilizer analysis, or "percentage by weight" of nitrogen, phosphorus and potassium, in that order. Find the three numbers from the fertilizer label and enter them below, in order, one number in each box. Then click "Calculate"