Effect of dosing aid size and consumer age on detergent dosage and discrepancies between perceived and measured laundry load in household washing

Abstract A laboratory study of 97 participants, designed to simulate home laundry conditions, was conducted to investigate the effect of dosing aid size on detergent usage. Each participant used two differently sized dosing aids when dosing their usual detergent. Participants used an average of 75.7 ml of detergent across both dosing aid conditions, which was approximately 15 % below the recommended amount. On average, the amount dosed with the large dosing aid was 16 % higher than with the small one, corresponding to a mean difference of 11.1 ml. This relative increase was more pronounced among younger users (18–29 years), who dosed 23 % more with the large aid compared to the small one, while older participants showed an increase of only 12 %. Surprisingly, even when instructed to load 7 kg-capacity machines, participants loaded on average only (3.4 ± 0.9) kg in a cotton program. This confirms earlier findings that perceived fullness often diverges from technical capacity. Since dosing aids are no longer included with most detergent packages, the findings highlight the continued relevance of dosing tools and the persistent mismatch between consumer behavior and manufacturer recommendations.