Onion Grades and Size Specifications Explained
Published by Assurex International Traders3 min read
The short answer
Export onions are graded mainly by size band (diameter in millimetres), colour and condition, with maximum tolerances for defects such as sprouting, rot, damage and out-of-size bulbs. A clear specification states each parameter as a measurable limit, together with packing and the inspection method.
Why grading matters
"Good quality onions" means different things to different buyers. A supermarket may want uniform medium bulbs with bright skins; a processor may care more about dry matter and price than appearance. Grading turns those preferences into measurable terms.
Size bands
Onion size is measured across the widest diameter of the bulb. Lots are sorted into size bands, such as 25–40 mm, 40–60 mm or 55 mm and above. Exact bands vary by market and supplier, so state the band you need and the tolerance for bulbs outside it.
Choosing a size band
- Retail packs often favour uniform small-to-medium bulbs.
- Wholesale markets may prefer medium-to-large bulbs.
- Food service and processing may prioritise yield over uniformity.
Colour
Indian red onions range from light red to deep red-purple. Specify the colour expected and how much variation is acceptable within a lot.
Condition
Condition describes the physical state of the bulbs:
- dry, well-cured necks
- firm bulbs
- intact outer skins (with tolerance for some loose skin)
- no free moisture
Defect tolerances
Specifications usually set a maximum percentage for:
| Defect | Description |
|---|---|
| Sprouted bulbs | Visible green shoots |
| Rot or mould | Soft, decaying or mouldy bulbs |
| Mechanical damage | Cuts, bruises or crushing |
| Doubles | Split or twin bulbs |
| Out-of-size | Bulbs outside the agreed band |
Writing an onion specification
A practical onion specification includes:
- Product description (Indian red onions, fresh, dry)
- Size band and tolerance
- Colour and acceptable variation
- Condition requirements
- Defect tolerances
- Packing — bag type and net weight
- Inspection method and timing
Illustrative example only: "Indian red onions, size 45–65 mm with 5% tolerance, red colour, dry necks, firm, max 2% sprouted, max 1% rotten, packed in 20 kg red mesh bags, pre-shipment inspection by agreed agency." Replace these figures with your market's requirements.
Next steps
See our onion product page and the commercial buyer's guide, or request an onion quotation.
