What do people get wrong about how much detergent to use?
This answer is a draft. It stays unpublished until legal review and source verification are complete.
"More detergent gets things cleaner" is one of the most stubborn laundry myths in the world. In Japan detergents have become highly concentrated, so "one cap" means something different for every product, and the measuring itself has become a source of confusion, especially if you cannot read the Japanese label.
What to go on
| Point | Detail |
|---|---|
| Basis of the dose | Printed per product against water volume (L) or load weight (kg): "○ mL per 30 L of water", "○ g per 3 kg of laundry" |
| Concentrated types | One cap is anywhere from 10 to 25 mL, varying widely by product. Never measure with another product's cap |
| Too much | Rinse residue (skin irritation, yellowing, smell), food for mould in the drum, foam that lowers cleaning power |
| Too little | Dirt not removed, redeposition (loosened dirt settles back on the clothes) |
| Heavy soiling | Rather than more detergent: pre-wash, soak or spot-wash |
| Fabric softener | Do not add it at the same time as detergent (use the automatic dispenser). Keep to the stated dose |
- Detergent falls under Japan's Household Goods Quality Labelling Act, which makes it compulsory to state ingredients, pH type (acid/neutral/alkaline), the guide dose and precautions for use on the pack.
- Washing machines with automatic dosing give the wrong amount unless you set the detergent type (concentrated or standard).
- Overloading the machine means the water cannot circulate and the dirt stays, even with the right amount of detergent. Seven to eight tenths of the machine's rated capacity is the guide.
[Verify] Check the compulsory labelling items against the Consumer Affairs Agency's Quality Labelling Regulations for Miscellaneous Manufactured Goods. The dose on the product label always takes priority.
Misunderstanding 1｜More foam means it is washing better
Foam is not a measure of cleaning power. Excess foam stops the clothes rubbing against each other, lowers cleaning power and hinders rinsing. In a front-loader the sensor detects the foam and adds extra rinses, wasting water and time.
Misunderstanding 2｜One cap is the same for every detergent
Products differ by 10 to 25 mL or more. Look at the lines on that bottle's own cap and match them to the water volume on the label.
Misunderstanding 3｜No lingering scent means not enough detergent
Lingering scent is about fragrance and fabric softener, not detergent. More detergent does not make the wash any cleaner (see our article on fabric softener).
Misunderstanding 4｜For soaking, the more detergent you dissolve the better
Soaking also works at the stated concentration; what does the work is time (30 minutes to several hours). A stronger solution adds nothing and causes colours to run on patterned items.
Misunderstanding 5｜Using less detergent is being stingy
The right dose is the cleanest and the gentlest on skin and machine alike: that is the makers' own guidance. Keeping a measuring cup next to the washing machine is a habit shared among people living in Japan.
---
Sources
- Consumer Affairs Agency, "Household Goods Quality Labelling Act: Quality Labelling Regulations for Miscellaneous Manufactured Goods (detergents)" [家庭用品品質表示法 雑貨工業品品質表示規程（洗剤）]
https://www.caa.go.jp/policies/policy/representation/household_goods/guide/zakka/
- Japan Soap and Detergent Association (JSDA), "Using detergent correctly" [洗剤の正しい使い方]
https://jsda.org/w/index.html
- Association for Electric Home Appliances (AEHA), "Using your washing machine well" [洗濯機の上手な使い方]
https://www.aeha.or.jp/
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
About this article
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
This is general information. Results vary from person to person and depend on your own conditions and surroundings.
Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.
Follow the care label and the maker's instructions for any garment, shoe or bag. For expensive or sentimental items, ask a specialist cleaner or repairer.
Sources
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