DAP Calculator
Calculate DAP and urea bags, exact application kg, leftovers, nitrogen credit and field coverage.
Calculations stay in this browser. If you choose Copy link, the entered field and dose values are placed in the page URL so the link can reproduce them; that URL can appear in browser history and may be visible to anyone you share it with.
Turns a phosphorus and nitrogen recommendation into whole DAP and urea bags to buy, exact kilograms to apply and leftovers, or works backwards from DAP bags already in stock to field coverage.
How to use it
- 1Enter your land and pick your unit — bigha, katha, guntha, cent, dismil, acre or hectare.
- 2Type the phosphorus figure from your recommendation, as P₂O₅, per hectare or per acre.
- 3Add the nitrogen figure, or enter zero, and the tool deducts the nitrogen already supplied by DAP before calculating urea.
- 4Switch to "What will my bags cover?" to see the selected land units covered, percentage of your field and residual urea requirement.
Example
- Input
- 1 acre, 60 kg P₂O₅ per hectare, 120 kg N per hectare
- Output
- Buy 2 DAP bags and apply 52.8 kg; buy 2 urea bags and apply 84.9 kg
The purchase list uses 50 kg DAP bags and 45 kg urea bags, rounds buying up, and keeps application quantities exact. Here 47.2 kg DAP and 5.1 kg urea remain rather than being over-applied.
What happens to your data
DAP is fixed at 18% N and 46% P₂O₅ and the India bag assumptions are stated beside the results. Everything is arithmetic in the page; nothing is uploaded. The tool converts a recommendation you already have and does not prescribe a crop dose.
Last updated September 2026
DAP — di-ammonium phosphate — is bought for phosphorus and it is also 18% nitrogen. That second number is where the money leaks.
Work out the DAP from the phosphorus recommendation, then work out the urea from the nitrogen recommendation, and you have quietly bought the same nitrogen twice. On a 120-60-40 dose that is 105.6 kg of urea where 84.9 kg was needed — 20.7 kg wasted on one acre — and a field that receives 143.5 kg of nitrogen when 120 was wanted. Too much nitrogen is not a harmless surplus: it lodges wheat and paddy, delays maturity and pulls in pests.
Enter your land in the unit you use and the phosphorus you need, and this gives the bags of DAP to buy. Add the nitrogen figure and it also shows what the DAP already covers and how much less urea that means. There is a second mode for the other direction — bags already sitting in the shed, and what they actually supply across the field.
How it works
Toolvore uses DAP at 18% nitrogen and 46% P₂O₅. Required P₂O₅ is divided by 0.46 to get the exact DAP application weight. Purchasing is a separate step: 52.8 kg to apply means buying two 50 kg DAP bags, applying 52.8 kg and keeping 47.2 kg rather than calling the answer 1.1 purchasable bags.
When a positive nitrogen target is supplied, the calculator subtracts the nitrogen already delivered by DAP before dividing the remainder by urea's 46% grade. Urea purchasing uses India's 45 kg bag, again separating whole bags to buy from kilograms to apply and leftovers. Entering zero deliberately skips the urea recommendation and nitrogen-excess warning rather than pretending zero is a crop target. If DAP exceeds a positive nitrogen target, the page advises discussing a phosphorus source without nitrogen instead of prescribing a replacement.
Regional and custom land units are converted to hectares before the nutrient arithmetic. Reverse mode starts with DAP bags already in stock, calculates P₂O₅-limited area coverage in the selected land unit and as a percentage of the entered field, then applies the same optional nitrogen credit to that covered area.
The share button updates the address bar with the current inputs and copies it when permitted. Everything runs locally and converts a dose you supply; it does not select the agronomic dose or application timing.
Common use cases
- Working out bags of DAP for a field measured in bigha, katha or guntha rather than hectares
- Seeing how much urea the nitrogen in DAP replaces, instead of buying both at full rate
- Checking whether DAP alone already over-supplies nitrogen for a low-nitrogen crop
- Finding out what bags already bought will actually cover
- Deciding between DAP and SSP when the nitrogen requirement is small
Frequently asked questions
Why does buying DAP change how much urea I need?＋
Because DAP is 18% nitrogen as well as 46% phosphorus. Buy 130.4 kg of DAP per hectare for the phosphorus and 23.5 kg of nitrogen per hectare arrives with it, whether you planned for it or not. If you then buy urea for the full nitrogen figure you have paid for that nitrogen twice and applied 143.5 kg where 120 was wanted. The correct urea figure is 209.8 kg per hectare rather than 260.9 — on a single acre that is 20.7 kg of urea saved.
How many bags of DAP is one acre?＋
It depends entirely on the phosphorus recommendation. At 60 kg P₂O₅ per hectare, one acre needs 52.8 kg DAP: buy two 50 kg bags, apply 52.8 kg and keep 47.2 kg. A decimal bag count is useful arithmetic but not a purchase instruction, which is why the result separates buying from application.
Is too much nitrogen actually a problem, or just wasted money?＋
Both. Excess nitrogen pushes leafy growth at the expense of grain, makes wheat and paddy lodge — fall over before harvest — delays maturity and attracts pests, and what the crop does not take up leaches away. So the over-application costs you the urea you did not need and can cost you part of the yield as well.
When should I use SSP instead of DAP?＋
When you need phosphorus but little nitrogen, and when the crop wants sulphur. SSP is 16% phosphorus with no nitrogen at all, plus 11% sulphur and 19% calcium, which is why it suits oilseeds and pulses. The trade is weight: at 16% against DAP's 46% you carry nearly three times as many bags for the same phosphorus. If this page tells you the DAP alone already over-supplies your nitrogen, that is the signal to look at SSP.
My bigha is a different size to the one shown.＋
There is no single bigha, so they are listed separately by region with the definition printed underneath the box — UP, Bihar and Rajasthan pucca at 3,025 square yards, West Bengal and Assam at 1,600, Madhya Pradesh at 12,000 square feet. Those disagree between sources and sometimes between districts. Choose "My own local unit" at the bottom of the list and enter how many square feet are in one of yours, and everything is computed from that instead.
Does this tell me my phosphorus recommendation?＋
No. What phosphorus a field needs depends on the soil, the crop, the variety and what grew there last season, and none of that is knowable from a web page. Bring the figure from your soil health card, your state agriculture department or your nearest Krishi Vigyan Kendra. This does the arithmetic between that recommendation and the bags at the shop, which is the part worth automating.
Related tools
Fertilizer Calculator
Find a least-cost whole-bag mix for an N-P-K target using your products, prices, stock and dealer limits.
Unit Converter
Convert length, weight and temperature — mm to inches, kg to pounds, Celsius to Fahrenheit.
Percentage Calculator
Calculate percentages, reverse changes, compound changes and percentage points with a CSV breakdown.
Volume Calculator
Calculate mixed-unit shapes and partly filled tanks, with diameter input and a CSV calculation.