How to Read an NPK Label: Compare Grade and Delivered Cost
Decision details
Fits if: Buyers who want to understand or compare NPK grades before requesting a quote.
Main drawback: Bag figures alone do not set the right rate or grade for every crop.
Compare: Crop and stage, full product label, net weight, price and delivery.
In this guide
The NPK figures are a quick way to read the nutrients declared on a bag. 15-15-15 lists equal weight percentages of N, P₂O₅ and K₂O. In 12-12-17-2, the declared K₂O share is higher than N and P₂O₅; read the extra figure with its unit on the label. For a purchase, separate two decisions: does crop guidance support the grade, and does its price compare well on the same labelled nutrient and pack basis? These formulas are not equivalent products or universal crop recommendations.
Which grades should I compare?
Start with the crop, stage and application system you use, then look for a programme that names that scope. The Department of Agriculture home-container guide uses NPK 15:15:15 for kailan. For a mature fruit-tree example, Penang’s durian guide lists 12:12:17:2+TE or 13:13:20:2+TE. These examples have different scopes; do not transfer a grade or rate to another crop or application method. [source] [source]
| Label you see | What the figures tell you | Buying check |
|---|---|---|
| 15-15-15 | Equal declared N, P₂O₅ and K₂O percentages | Compare with a crop programme that names this grade; check the full formula |
| 12-12-17-2+TE | Penang's durian guide lists this for mature durian; it is not a palm recommendation or universal grade | Confirm that the full product label matches the programme formula before comparing price [source] |
Use one worksheet for each bag
Copy the net weight and individual nutrient percentages from the label of the exact product being offered. Use product weight, not the shipping carton weight. Pick one nutrient first so the comparison has a clear basis: N against N, P₂O₅ against P₂O₅ or K₂O against K₂O. Do not mix elemental P with P₂O₅, or K with K₂O, without a verified basis conversion.
On a 15-15-15 label, each of the three stated nutrient fractions is 15 ÷ 100 = 0.15. Multiply the printed net bag weight by 0.15 to obtain the labelled mass of one of those nutrients. On a 12-12-17 label, the K₂O fraction is 17 ÷ 100 = 0.17, while N is 0.12. Use the figure for the nutrient you are comparing; adding all three figures does not give the nitrogen content. This reads declared label content, not the amount a plant will necessarily absorb. [source]
| Record for each offer | Calculation or check |
|---|---|
| Product name, full grade and net weight in kg | Use the weight and analysis of the product named in the quote. |
| One nutrient and its declared percentage | Labelled nutrient mass = net weight × percentage ÷ 100. |
| Quoted price for one bag | Cost per kg of the labelled nutrient = bag price ÷ that nutrient mass. |
| Bag quantity and delivery to your postcode | Record the order total separately so delivery is not counted twice. |
If the individual percentage is missing or zero, do not divide the price by that nutrient mass: the denominator is missing or zero, so its cost per kg cannot be calculated. Request the complete label. Zero content for one nutrient does not mean the product is free or equal in its other nutrients. If a genuine offer has a zero bag price and positive nutrient mass, the quotient is zero; confirm what the offer includes and any other charges before comparing it. [source]
This worksheet helps inspect the price of declared content. It does not set kg per tree, replace soil analysis or prove that the lowest unit cost gives the best yield. For a buying decision, match the product to the crop programme first, then compare the same grade, order quantity and delivered total.
What should I check before paying?
Read the full formula, net weight and label instructions. Request a dated quote for the same grade and bag size, including delivery to your postcode. If you do not have a crop-specific programme, check with a local agricultural adviser before choosing a rate; nutrient stewardship depends on the right source, rate, timing and placement. [source]
GrowEasy NPK is offered by enquiry only; there is no public price to treat as a quote. Ask what is available, request the label and get a written delivered quote. [source]
Also read: 15-15-15 explained · 12-12-17-2 explained · dated NPK price examples
How to check an NPK label before requesting a quote
Read the complete product label
Record the product name, full grade, net weight and the individual N, P₂O₅ or K₂O percentage you want to compare.
Calculate one labelled nutrient mass
Multiply net weight in kg by its individual label percentage, then divide by 100. If the percentage is missing or zero, do not calculate that nutrient’s cost per kg.
Compare the same basis and units
Compare N with N, P₂O₅ with P₂O₅ or K₂O with K₂O. Divide bag price by positive labelled nutrient mass; this is not a rate to apply to plants.
Request a matching written quote
Send your crop, stage and postcode. Request the label, grade, pack weight, bag quantity and written total including delivery.
Frequently asked questions
What do the three NPK figures mean?
They state the weight percentages of N, P₂O₅ and K₂O declared on the label. Check the full formula before comparing bags.
When should I choose 15-15-15 or 12-12-17-2+TE?
Follow a programme that names your crop and stage. DOA lists 15:15:15 for home-container kailan; Penang's guide lists 12:12:17:2+TE or 13:13:20:2+TE for mature durian. Do not transfer either example to another crop. [source] [source]
Does GrowEasy publish an NPK price?
No. The supplier says NPK is offered by enquiry only. Request the label, availability and a written delivered quote. [source]
How do I choose between two bags after reading the label?
First check that crop guidance supports each grade. To compare declared nutrient cost, choose one matching basis—N, P₂O₅ or K₂O—calculate its labelled mass from net weight and percentage, then divide the bag price by that mass. Compare the final total for the same quantity and delivery scope. Cost per kg of labelled nutrient is not an application rate or proof of yield. [source]