Fertilizer Calculator — Urea, DAP & Potash Bags per Acre
Agricultural advice is usually given as kilograms of nutrients per acre — nitrogen (N), phosphorus (P₂O₅) and potash (K₂O). Farmers buy fertilizer by the bag. This calculator converts one into the other.
Updated
Results are estimates for planning. Actual figures depend on local conditions, prices and quotes — verify before making decisions.
About this calculator
Pick a crop to load a typical recommendation, or enter the figures from your soil test report or agriculture extension officer.
Formula
DAP (kg) = P₂O₅ needed ÷ 0.46
N from DAP = DAP × 0.18
Urea (kg) = (N needed − N from DAP) ÷ 0.46
SOP (kg) = K₂O ÷ 0.50 | MOP (kg) = K₂O ÷ 0.60
Bags = kg ÷ 50
DAP is used first to supply phosphorus. Because DAP also contains 18% nitrogen, that nitrogen is subtracted before working out how much urea is still needed.
Examples
Wheat, 1 acre
For 1 acre: 2 bags DAP, 1.48 bags urea, 1 bags SOP
Maize, 5 acres
For 5 acre: 10 bags DAP, 17.83 bags urea, 10 bags SOP
Cotton, 10 kanal
For 10 kanal: 1.63 bags DAP, 3.17 bags urea, 1.25 bags SOP
Reference table
| Fertilizer | N | P₂O₅ | K₂O | Nutrient per 50 kg bag |
|---|---|---|---|---|
| Urea | 46% | — | — | 23 kg N |
| DAP | 18% | 46% | — | 9 kg N + 23 kg P₂O₅ |
| SOP (potassium sulphate) | — | — | 50% | 25 kg K₂O |
| MOP (potassium chloride) | — | — | 60% | 30 kg K₂O |
Important information
- Crop presets are general guidelines. Recommendations differ by province, irrigated vs rain-fed (barani) land, previous crop and soil test results.
- Apply phosphorus and potash mostly at sowing; split nitrogen (urea) across 2–3 doses with irrigation as advised for your crop.
- SOP is usually preferred for tobacco, potatoes and saline soils; MOP is cheaper per unit of potash.
- Default prices and costs are examples only — replace them with this season's prices from your local market and dealers.
- 1 maund = 40 kg. Areas can be entered in acres, kanal (1/8 acre) or hectares.
Frequently asked questions
How many bags of DAP and urea per acre for wheat?
With the default guideline (about 52 kg N and 46 kg P₂O₅ per acre) you need 2 bags of DAP and about 1.5 bags of urea per acre. Your local recommendation may differ.
Why does the calculator reduce urea when I add DAP?
Each bag of DAP also provides 9 kg of nitrogen, so less urea is needed to reach the same total nitrogen.
Can I use NP or nitrophos instead of DAP?
Yes, but the nutrient percentages differ (e.g. NP 18-18 or 22-20). Work out the kg of nutrients they supply and reduce DAP and urea accordingly.
What does N-P-K mean?
Nitrogen, phosphorus (as P₂O₅) and potassium (as K₂O) — the three main plant nutrients. Fertilizer grades show their percentages.
Do I need a soil test?
A soil test is the best way to avoid over- or under-fertilizing. Provincial soil-testing labs offer tests at low cost.
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