Vacuum suction figures, and why they mislead

Vacuum marketing has settled on a number-led arms race, and the numbers are not measured the same way twice.

The units

Pascals or kilopascals measure sealed suction — how hard the motor pulls with the inlet blocked. Impressive on paper, and no vacuum ever works blocked.

Air watts combine suction and airflow, which is closer to real cleaning, but the test conditions are chosen by the manufacturer.

Neither number can be compared between brands with any confidence. A figure that is twice as large does not mean a machine that cleans twice as well.

What actually picks up dirt

The floor head. More than anything else. A good motorised brush roll on carpet, and a soft roller on hard floors, outperform raw suction. This is why some machines with modest figures clean better than rivals quoting double.

Seal quality. Air leaking anywhere between head and motor throws the numbers away.

Filtration. A vacuum that clogs loses suction within minutes. Washable filters that you actually wash keep it.

Cordless: the runtime lie

Quoted runtimes are measured on the lowest setting with a non-powered head. On carpet, with the brush roll running, expect roughly a third of it. Boost modes are typically six to ten minutes.

If you have a house rather than a flat, check whether the battery is removable. A second battery doubles the machine; a sealed one means the vacuum's life ends when the cells do.

Bagged or bagless

Bagless is cheaper to run and messier to empty. Bagged holds more, contains dust properly on emptying, and costs a few pounds a year in bags. For allergy sufferers, bagged with a sealed system is meaningfully better.

Pricing

Vacuums carry some of the most inflated RRPs in UK retail, alongside fashion watches. A "half price" cordless is usually at its normal selling price. Check the price history rather than the claim — genuine drops on this category do happen, typically in January and around Black Friday, but they are far rarer than the advertising suggests.