Free practical tools
Calculators that help before you buy
These tools turn common household questions into simple numbers. They are designed to help you plan first, then decide whether a product is actually necessary.
Water & resilience
72-hour household water calculator
Estimate a simple drinking-water planning quantity for a short household disruption.
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Water & filtration
Water filter running cost calculator
Estimate replacement-filter spend and total ownership cost instead of comparing day-one prices alone.
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Air quality & damp
Dehumidifier running cost calculator
Estimate daily, monthly and annual electricity cost using appliance wattage, runtime and your own tariff.
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Why we build tools
A useful calculator can answer part of the decision without requiring you to buy anything. Where a product comparison is relevant, the tool links to the appropriate guide afterwards.