a rule of thumb
a rough practical guideline based on experience
In Spanish
a rough practical guideline based on experience
Examples
- As a rule of thumb, code reviews should take 30-60 minutes.
- A good rule of thumb is to water your plants once a week.
- As a rule of thumb, always save 20% of your income for emergencies.
When it's used
Commonly used in English to refer to a practical guideline based on experience, especially when precise measurements aren't needed. It's informal and found in both speech and writing, though more often in everyday conversation.
The common mistake
Spanish speakers might say 'a general rule' or 'an empirical rule', which are not idiomatic in English. It's important to use the complete expression 'a rule of thumb' to sound natural.
Related idioms
FROM WHAT YOU READ TO WHAT YOU SAY
Recognising it isn't the same as using it
Reading an idiom and understanding it is step one. Dropping it into a conversation, at the right moment, without stopping to think, is another — and that only comes from speaking.
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