Produce
Onions
Onions have a natural chemical defence, papery outer layers that get discarded, and one of the lowest residue indices measured. They are also the cheapest flavour base in the store.
Organic upgrade priority
Conventional is a reasonable budget choice
Score 4/100 · about $1.13 a week extra for a household of two
- →Conventional samples index 13/100 against 8/100 for organic — a 5-point difference.
- →At about 3.6 servings a week, the difference applies to a smaller share of what you eat.
- →Sample confidence is moderate, so the score is weighted down by 10%.
Key numbers
- Residue evidence
- 13/100
- Lower residue evidence
- Nutrient density
- 66/100
- Per calorie, across the whole database
- Typical price
- $3.79
- per 3 lb bag · organic +40%
- Servings a week
- 3.6
- Per person, at typical purchase volume
- Samples
- 1,503
- Conventional, 2017–2024 · 71 organic
- Data confidence
- Moderate
- Set from sample size and year coverage
Organic vs conventional onions
| Measure | Conventional | Organic |
|---|---|---|
| Samples analysed | 1,503 | 71 |
| Program years | 2017–2024 | 2017–2024 |
| Samples with any residue | 25% | 18% |
| Mean residues per sample | 0.3 | 0.2 |
| Samples above the EPA tolerance | 0.27% | 0.00% |
| Relative residue evidence index | 13/100 | 8/100 |
| Typical price | $3.79 / 3 lb bag | $5.29 / 3 lb bag |
Nutrition
Per 1 cup chopped (160 g).
64
calories
1.8 g
protein
2.7 g
fiber
6.8 g
sugar
- Quercetin
- Prebiotic fructans
- Vitamin C 13% DV
How to wash onions
Peel and discard the dry outer layers. No wash needed beyond rinsing the knife and board.
Washing reduces surface residue and soil. It does not remove systemic compounds taken up into the plant, and no soap, vinegar, or commercial produce wash has been shown to beat 30 seconds of plain running water by a margin worth paying for. Full washing guide.
Buying and storing
- ◆Chilling an onion for 15 minutes before cutting slows the enzyme reaction that makes you cry, and a sharp knife does the rest.
- ◆Most of the quercetin sits in the outermost edible layers, so aggressive peeling costs you more than it saves.
Common questions
›Should I buy organic onions?
Probably not, if money is tight. Onions indexes 13/100 on relative residue evidence against 8/100 for organic — a difference small enough that the same dollars buy far more on leafy greens or berries.
›Are onions high in pesticides?
Onions shows lower residue evidence — an index of 13/100 relative to other commodities. Across 1,503 conventional samples from 2017–2024, 25% contained at least one detected residue, averaging 0.3 distinct compounds per sample, and 0.27% exceeded the applicable EPA tolerance. A detection is not the same as an unsafe level.
›How much more does organic onions cost?
About 40% more at typical U.S. retail — $3.79 per 3 lb bag conventional against $5.29 organic. For a household of 2 at normal purchase volume that is roughly $1.13 a week.
›How should I wash onions?
Peel and discard the dry outer layers. No wash needed beyond rinsing the knife and board.
Related foods
Spinach
$3.29 / 5 oz container · organic $4.49
Kale
$2.79 / bunch · organic $3.79
Broccoli
$2.49 / lb · organic $3.69
Bell peppers
$1.49 / each · organic $2.29