NPK Ratio Calculator

Work out npk ratio instantly with clear inputs, formula shown and shareable results.

About NPK Ratio Calculator

Converts the label percentages into kilograms of each nutrient applied and reduces the analysis to its simplest ratio.

Formula

NPK arithmetic

Nutrient applied = label percentage / 100 x fertiliser mass; a 10-26-26 product supplies 10 kg N per 100 kg

Worked example

With the default values below, NPK Ratio Calculator returns Nitrogen applied of 20.000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Nitrogenaccepts 0–100 %: 10 %
Phosphate as P2O5accepts 0–100 %: 26 %
Potash as K2Oaccepts 0–100 %: 26 %
Fertiliser appliedaccepts 0.1–100,000 kg: 200 kg

Results

Nitrogen applied: 20.000 kg
Phosphate applied: 52.000 kg P2O5
Potash applied: 52.000 kg K2O
Simplified NPK ratio: 1 : 2.6 : 2.6

Step by step

1Values used
2NPK arithmetic
3Nitrogen applied= 20.000 kg
4Phosphate applied= 52.000 kg P2O5
5Potash applied= 52.000 kg K2O
6Simplified NPK ratio= 1 : 2.6 : 2.6

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What do the three numbers mean?

Percentage nitrogen, phosphate as P2O5 and potash as K2O by mass, in that fixed order.

Why not elemental phosphorus?

Historical convention; P2O5 is 43.6% phosphorus, so 26% P2O5 is about 11.3% actual P.