When converting units, be aware that not all the imperial measures are the same in US and UK English (let alone the equivalent legacy words in Dutch).
Genuine errors I’ve had to sort out for clients include a car company that was accusing a competitor of falsifying its miles-per-gallon figures, an edcuational publisher getting its online tests wrong, and a meteorological website getting confused about why a temperature of minus ten meant forty-two degrees of frost. And where the old terms are still used, it’s generally only in specific contexts: you’d never weigh a car in stones or give absolute zero in Fahrenheit. So here are a few pointers:
- Liquid volumes are the big bugbear: watch out with gallons, pints, quarts and fluid ounces – they’re all a bit different! Cups and spoonfuls in American recipes are defined units, but English people wouldn’t necessarily know them.
- Stones are an oddity: fourteen pounds, still common in the UK for people’s weights but nothing much else. Not used in the US (they use pounds).
- The UK ton (or sometimes tonne) is twenty hundredweight of eight stone each of fourteen pounds… oh, to cut a long story short, it’s a tad bigger than a metric ton, whereas the US ton of two thousand pounds is nearly 10% less.
- You definitely don’t want to use the Dutch “ons” (100g) as an “ounce” (<30g) in a recipe! A “pond” (half kilo) is fortunately only about 10% different from a pound…
- Lengths are OK: inches, feet, yards, miles, etc. are the same on both sides of the Atlantic. Still widely used for technical specs, people’s height, distances between towns
Remember that everyone in the UK knows the metric units now: even as a very little kid at school in the early seventies, I was taught in centimetres and so forth. And even Americans use SI units in scientific contexts.
Prevalence: low. Not a common issue, fortunately – most people don’t bother converting. In fact, I suspect the mistakes are more common when conversion is required during translation into Dutch.
Frequency: high. When such conversions are done, the number of mistakes I come across is surprisingly high.
Native: occasionally. Not all native speakers (Americans in particular) realise that the units aren’t all the same on both sides of The Pond.