Tools
Your conditions, not the test’s.
Every measurement on this site was taken under particular conditions — one tyre size, one bottle, one car. Quoting it at a reader whose conditions differ is how a good figure becomes a wrong answer. These take the measurement and do the arithmetic for your case, with the working shown rather than hidden.
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Inflation time
How long will your tyre take?
Every published inflator time is measured on one tyre. Enter your size and the measured times scale to it — the ratio survives an assumption the absolute figure could not.
Scaled from a 245/50R20
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Dilution
What does 1:10 actually mean?
Brands do not agree on whether the first number includes the water. Both readings, both answers, for any bottle and any ratio — because a calculator that silently picks one gives half its users the wrong answer.
Two readings, both shown
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Oil interval
Whose number is 3,000 miles?
Not your carmaker's, on most modern cars. Put your manual's interval in and see how many changes the habit adds over 100,000 miles.
Your number, not ours
One more lives outside this section, because it was built before this section existed and its URL is worth more than the tidiness would be: the home-charging amperage calculator takes your breaker and your car's onboard limit and returns the lower of the two, which is the rate you will actually get.
None of these invents an input. Where a figure has to come from your manual, your bottle or your receipt, the box starts empty rather than carrying a plausible-looking default — a default is a guess wearing the clothes of a measurement.