Fertilizer Calculator

Find a least-cost whole-bag mix for an N-P-K target using your products, prices, stock and dealer limits.

This tool runs entirely in your browser. Your data is never uploaded, never stored, and never leaves your device.

Finds the least-cost whole-bag purchase that meets the N, P₂O₅ and K₂O target you supply, using bags already in stock first and proving the result across up to eight editable fertilizer products.

How to use it

1Enter the field area in hectare, acre, a listed regional unit or a custom square-foot unit, then enter the soil-test/adviser target per hectare or acre.
2Edit up to eight products with their N-P₂O₅-K₂O grade, bag size, actual price, whole bags in stock and any dealer purchase limit.
3Choose no nutrient-surplus ceiling or a hard 10%, 25% or 50% ceiling, then review the proven Optimal plan—or the clearly labelled Best found or infeasible result—and every nutrient surplus.
4Copy or print the purchase/application worksheet, or switch to Analyse bags I have to enter partial bags and see the resulting kg/ha.

Example

Input: 1 acre, 120-60-40 per hectare (the built-in defaults)
Output: Optimal purchase: 2 bags of urea, 1 DAP, 1 MOP and 1 SSP for ₹3,236, supplying 50.4 kg N, 31 kg P₂O₅ and 30 kg K₂O

The one-acre targets are 48.56, 24.28 and 16.19 kg, so whole bags create visible surpluses rather than pretending to hit fractional quantities exactly. This result uses the six default example products and prices with no stock and no surplus cap; changing price, stock, grade or availability can change the optimum.

What happens to your data

The bounded integer search and reverse analysis run locally; no field, price or stock data is uploaded. The included products and prices are examples to replace, not live recommendations. The tool accepts targets from a soil test or qualified adviser and never chooses crop dose, product suitability or timing; local agronomy, soil, irrigation and regulations still govern the real plan. Over-broad or invalid searches are refused rather than filled with a guessed answer.

Last updated September 2026

Turn a soil-test or adviser-supplied N–P₂O₅–K₂O target into a least-purchase-cost whole-bag plan. Enter the field area, nutrient target, current dealer prices, bag sizes, stock on hand, and any purchase limits; the optimizer compares editable straight, complex, or custom fertilizer products.

This is a purchasing and arithmetic tool, not an agronomic prescription. It never chooses the crop dose, nutrient form, placement, timing, or suitability for your soil—those inputs belong with a qualified local adviser.

How it works

The optimizer searches integer bag combinations, uses available stock before purchases, and ranks feasible plans by purchase cost. Equal-cost plans favour lower nutrient surplus and then fewer bags. Optional 10%, 25%, or 50% surplus ceilings are hard constraints and can make a plan infeasible.

A completed exact search is labelled Optimal. If the bounded search budget is reached, the result is labelled Best found rather than presented as a proof of the cheapest possible plan. Every selected bag is allocated in full, and the result shows purchase bags, stock used, delivered nutrients, shortfall, and surplus warnings.

Area can be entered in hectares, acres, supported regional bigha conventions, or a custom square-foot conversion. Copy or print the purchase worksheet and leave the application schedule for the adviser. The separate reverse analysis accepts partial bags to calculate what an existing mix supplies per hectare.

Common use cases

Compare current dealer prices across editable fertilizer products
Use whole bags already in storage before buying more
Set stock or maximum-purchase constraints
Check nutrient surplus before accepting a cheap blend
Prepare a purchase worksheet from an adviser-approved nutrient target
Analyse nutrients supplied by bags already available

Frequently asked questions

Does the calculator recommend how much fertilizer my crop needs?＋

No. Enter the N, P₂O₅, and K₂O target supplied by a soil test, agronomist, or local adviser. The tool only converts that approved target into a bag-purchase plan.

Is the cheapest fertilizer plan automatically the best agronomic plan?＋

No. Lowest purchase cost does not establish crop suitability, nutrient availability, secondary nutrients, soil effects, timing, placement, or local recommendations. Review the worksheet with a qualified adviser.

How are stock and purchase limits handled?＋

Stock is available at zero new purchase cost and is used before buying additional whole bags. An optional maximum-purchase value caps new bags for that product.

Why can a plan show nutrient surplus or no feasible result?＋

Whole-bag sizes rarely match three nutrient targets exactly. The tool warns about surplus; a hard surplus ceiling, limited products, or strict stock limits may leave no valid combination.

What do Optimal and Best found mean?＋

Optimal means the bounded integer search completed and proved the displayed least-cost result for the entered model. Best found means it reached its search budget and is the best feasible plan found, not a proof of global minimum cost.

Can I add a custom fertilizer or local land unit?＋

Yes. Edit product names, nutrient grades, bag sizes, prices, stock, and purchase caps. For land, use the matching regional bigha convention or enter your own square-feet conversion.

Are my farm figures sent to a server?＋

No. Optimization, reverse analysis, copying, and printing run locally in your browser.