Fertilizer amount·Compound NPK 20-20-20 · 100 m²
Compound NPK 20-20-20
5 kg
100 m² · N 10 g/m²
Content 20%

Compound NPK 20-20-20 on 100 m² — 5 kg for 10 g/m² of N

To put 10 g/m² of N on 100 m² with Compound NPK 20-20-20, spread 5 kg — that is 50 g per m². At 20% content it is simply the 1 kg of nutrient you need divided by that figure.

Fertilizer to spread

Urea is only 46% nitrogen, so putting 10 g of N down means spreading 10 ÷ 0.46 = 21.74 g of urea. Multiply instead and you get 4.6 g, a number that looks plausible enough to pass unnoticed. Whenever the content is below 100%, the fertilizer weight is always larger than the nutrient weight — that is the fastest check that you have the division the right way round.

  • N 5 g/m² · 25 g/m²2.5 kg
  • N 10 g/m² · 50 g/m²5 kg
  • N 15 g/m² · 75 g/m²7.5 kg
  • N 20 g/m² · 100 g/m²10 kg

Comes along with it

Matching 10 g/m² of N with a 21-17-17 puts the fertilizer at 47.62 g/m², and those 47.62 g carry 8.1 g of P₂O₅ and 8.1 g of K₂O with them. You do not get to choose: once the fertilizer weight is fixed, the other two are dragged along in proportion to their content. That is why one compound bag rarely hits all three targets. The order of work is to match one, then top up or accept the surplus with straight fertilizers.

  • P₂O₅ 20% · 10 g/m²1 kgP 436 g
  • K₂O 20% · 10 g/m²1 kgK 830 g
Fertilizer
Compound NPK 20-20-20 (20-20-20)
Area
100 m²
Nutrient matched
N
Content
20%
Nutrient needed
1 kg
Per m²
50 g

Nearby cells

Compound NPK 20-20-20
10 kgN 20%
Compound NPK 20-20-20
25 kgN 20%
Compound NPK 20-20-20
50 kgN 20%
Compound NPK 10-10-10
100 gN 10%

Same fertilizer, other areas

1 m²
50 gN 20%
5 m²
250 gN 20%
10 m²
500 gN 20%
20 m²
1 kgN 20%
50 m²
2.5 kgN 20%
100 m²
5 kgN 20%
200 m²
10 kgN 20%
500 m²
25 kgN 20%
1000 m²
50 kgN 20%

Same area, other fertilizers

Urea
2.17 kgN 46%
Ammonium sulfate
4.76 kgN 21%
Ammonium nitrate
2.94 kgN 34%
Calcium nitrate
6.45 kgN 15.5%
Diammonium phosphate DAP
2.17 kgP₂O₅ 46%
Monoammonium phosphate MAP
1.92 kgP₂O₅ 52%
Triple superphosphate TSP
2.17 kgP₂O₅ 46%
Potassium chloride MOP
1.67 kgK₂O 60%
Potassium sulfate SOP
2 kgK₂O 50%
Potassium nitrate
2.17 kgK₂O 46%
Monopotassium phosphate MKP
1.92 kgP₂O₅ 52%
Compound NPK 21-17-17
4.76 kgN 21%
Compound NPK 17-21-17
4.76 kgP₂O₅ 21%
Compound NPK 20-20-20
5 kgN 20%
Compound NPK 10-10-10
10 kgN 10%

Worth knowing

  • Fertilizer to spread = nutrient needed ÷ (content ÷ 100). It is a division, never a multiplication.
  • Nutrient needed = area × target rate, so twice the area means twice the fertilizer.
  • A fertilizer with half the content takes twice as much for the same nutrient — inverse proportion.
  • With a compound, matching one nutrient drags the other two in at their content ratio.

Common questions

Q. How much Compound NPK 20-20-20 goes on 100 m²?

At 10 g/m² of N, 5 kg — that is 50 g per m². It is the 1 kg of nutrient needed divided by the 20% content.

Q. If I double the target, do I double the fertilizer?

Yes. Target and fertilizer weight are directly proportional — 5 g/m² takes 2.5 kg and 20 g/m² takes 10 kg. Area behaves the same way: twice the area, twice the fertilizer.

Q. What else goes in along with it?

Matching N to the target also puts in P₂O₅ 1 kg, K₂O 1 kg. That is not a choice — those amounts are dragged in at their content ratio.