Fertilizer calculator

You pick a crop, which loads its recommended NPK dose in kilograms per hectare (kg/ha of N, P₂O₅ and K₂O). You then enter your plot area in ropani, bigha or hectare. The calculator converts the area to hectares (1 ropani = 0.0509 ha, 1 bigha = 0.6773 ha), scales the nutrient targets, and converts them into bags of urea, DAP and MOP using each product's nutrient content.

DAP (18-46-0) supplies all of the phosphorus: DAP kg = P₂O₅ ÷ 0.46. Because DAP also contains 18% nitrogen, that nitrogen (DAP × 0.18) is subtracted from the nitrogen target before sizing urea. Urea (46-0-0) then covers the remainder: urea kg = (N − N from DAP) ÷ 0.46. MOP (0-0-60) supplies potassium: MOP kg = K₂O ÷ 0.60.

The indicative blanket recommendations used here (kg/ha of N : P₂O₅ : K₂O) are rice 100:30:30, maize 120:60:40, wheat 100:50:25 and potato 100:100:60, with a general vegetable dose of 100:60:50. These follow NARC/MOALD guidance but vary by variety, season and soil — always confirm with a local soil test and extension officer.

One hectare is about 19.65 ropani (1 ropani = 0.0509 ha) in the hills, and about 1.476 bigha (1 bigha = 0.6773 ha) in the Terai. The calculator handles the conversion automatically, so you can enter your area in whichever unit you use locally.

Usually no. Phosphorus and potash (DAP, MOP) are typically applied as a basal dose at sowing or transplanting, while nitrogen (urea) is split into two or three top-dressings during the growing season to reduce losses. Follow crop-specific guidance from MOALD or your agriculture service centre.

No — they are planning estimates. Actual fertilizer needs depend on your soil's existing nutrients, organic manure already applied, crop variety, irrigation and target yield. Use the figures as a starting point and adjust based on a soil test and local advice. Fertilizer grades are assumed (urea 46-0-0, DAP 18-46-0, MOP 0-0-60); verify the analysis printed on your bag.