Cost per Nutrient & The Cheaper Source Wins
Compares urea vs DAP
Compare two fertilisers on the cost per kilogram of actual nutrient — not the sticker price per bag — to find the cheaper source of N, P or K, with the saving per kg and percent.
Fertiliser A
Next: buy the nutrient from the cheaper source for the bulk of your need, but still match the right nutrient form and timing to the crop.
Compare like-for-like nutrient (N with N, P₂O₅ with P₂O₅); also weigh application cost and nutrient form.
Cost per nutrient — key facts
- What matters
- cost per kg of actual nutrient
- Formula
- price ÷ (bag wt × nutrient% ÷ 100)
- Urea
- 46% N — concentrated nitrogen
- DAP
- 18% N, 46% P₂O₅
- Compare
- like-for-like (N with N)
- Also weigh
- application cost, form, timing
- Currencies
- 8 supported
- Privacy
- Runs in your browser; nothing uploaded
You buy nutrients, not bags
Fertiliser shopping is full of false bargains. A bag that looks cheap may be dilute, while a pricier, more concentrated product can deliver each kilogram of nitrogen or phosphate for less. The only fair test is to strip out the filler and the bag size and work out what one kilogram of the actual nutrient costs: price divided by the kilograms of nutrient the bag really contains. Do that for both products and the better deal stops being a guess.
This tool reports the cost per kg of nutrient and per kg of product for both fertilisers, the nutrient in each bag, the cheaper source, and the saving in money and percent. Compare the same nutrient between sources — N with N, P₂O₅ with P₂O₅ — and then temper the result with application cost, nutrient form and timing. Pair it with the Fertilizer (NPK) and Crop Nutrient Removal tools to buy the right nutrients at the right price.
See past the bag price
Cost per kg of real nutrient, not filler.
Name the cheaper source
Two products, one clear winner per nutrient.
Know the saving
Difference in money and percent per kg.
Buy in your currency
Eight currencies, like-for-like figures.
Frequently Asked Questions
Why compare cost per nutrient instead of per bag?+
The price on the bag tells you what you pay for the whole product, much of which is filler and carrier. What you actually buy is the nutrient inside it. A cheaper bag with a low nutrient content can cost more per kilogram of real nitrogen or phosphate than a dearer, more concentrated bag — so the bag price alone can steer you to the worse deal.
How is cost per kg of nutrient calculated?+
Cost per kg nutrient = price ÷ (bag weight × nutrient% ÷ 100). For example a 50 kg bag of urea (46% N) at a given price holds 23 kg of N, so divide the bag price by 23. Doing the same for the second fertiliser puts both on a level footing — the genuine cost of one kilogram of the nutrient you need.
What does the calculator output?+
It returns the cost per kg of actual nutrient for both fertilisers, the cost per kg of product, the kilograms of nutrient in each bag, which is the cheaper source, and the saving per kilogram in both currency and percent. That makes the better-value purchase obvious at a glance, whatever the headline bag prices look like.
Should I compare different nutrients against each other?+
No — compare like for like. Cost per kg of nitrogen should be set against another nitrogen source, and cost per kg of P₂O₅ against another phosphate source. Comparing the N cost of urea with the P cost of DAP is meaningless because they supply different nutrients; pick the nutrient you are actually buying and compare sources of that.
Does urea or DAP give cheaper nitrogen?+
Urea is usually the cheapest straight source of nitrogen because it is highly concentrated at 46% N. DAP carries nitrogen too (about 18% N) but you buy it mainly for its phosphate (46% P₂O₅), so its N often rides along. Enter both products' prices and analyses and the tool will name the cheaper source for the nutrient you choose.
Is the cheapest per nutrient always the best buy?+
Not always. Also weigh the application cost, the nutrient form and how well it suits your soil and timing — a slow-release or coated product may justify a higher unit cost, and a foliar grade is priced for a different job. Use cost per nutrient as the first filter, then adjust for agronomy and logistics.
Does it handle different bag sizes?+
Yes. Because the formula uses the bag weight and nutrient percentage you enter, it normalises everything to one kilogram of nutrient regardless of whether the bags are 25 kg, 45 kg or 50 kg. That is the whole point — it strips away both the bag size and the filler so you compare the actual nutrient cost.
Which currencies does it support?+
The calculator works in eight currencies, so you can enter prices in your local money and read the cost per nutrient and the saving in the same units. The arithmetic is identical across currencies — it simply keeps the figures in the one you choose for clear, like-for-like comparison.
What about secondary and micronutrients?+
The same logic applies to any nutrient on the label — sulphur, zinc, boron and so on. Enter the relevant nutrient percentage for each product and the tool gives the cost per kg of that nutrient. Just keep comparing the same nutrient between the two products so the result is meaningful.
How accurate is the comparison?+
It is exact for the prices and analyses you enter — the maths is straightforward. The accuracy of the decision depends on entering the correct bag weight, nutrient percentage and current price for each product. Use up-to-date local prices and the guaranteed analysis from the label for a comparison you can act on.