🧺 Detergent Dosage Calculator

Enter your laundry weight and water hardness to calculate a recommended detergent dose.

⚠️ A general guideline approximation — actual recommended amounts vary by brand and formulation. Always check the product label first.

Recommended Dose

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Liquid Detergent Equivalent (approx.) —

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GUIDE

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The Detergent Dosage Formula

Base dose (g) = Laundry weight (kg) × 10g — a commonly cited approximation for regular soil level. Multiply by a water-hardness factor: soft ×0.8, medium ×1.0, hard ×1.3. For example, 3kg of laundry with medium-hardness water gives 3 × 10 × 1.0 = 30g. Liquid detergent has a density close to water, so 1g ≈ 1mL is a reasonable approximation.

Why Water Hardness Changes the Dose

Hard water contains more calcium and magnesium, which react with detergent surfactants and reduce cleaning power (this is also why hard water leaves more soap residue). The same load therefore needs more detergent in hard-water areas to get the same cleaning result. Soft water has fewer minerals, so detergent works more efficiently and less is needed.

Frequently asked questions

Is this calculator's result the exact amount to use?

No. It's an approximation based on general guidelines — actual recommended amounts vary by detergent brand and concentration. Always check the product label first.

How do I know if my water is hard?

Check your local water utility's water quality report, or use an inexpensive water hardness test strip.

Does more detergent mean cleaner laundry?

No. Excess detergent can fail to rinse out fully, leaving residue on fabric and actually reducing cleaning effectiveness. Stick to the recommended amount.