THE IDIOM COLLECTION LEARN & PRACTISE
Rule of thumb
Understand the meaning. See it in context. Make it yours.
01 / UNDERSTAND
Meaning in plain English
A practical, approximate guide based on experience rather than an exact rule.
02 / SEE IT IN CONTEXT
The expression in a sentence
- As a rule of thumb, I leave extra time when travelling to an unfamiliar venue.
03 / CHECK YOUR UNDERSTANDING
Quick idiom quiz
Try the question without looking back, then write a sentence of your own. You can retry as often as you like.
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Can you recall the expression?
Complete the example using the expression from this lesson.
As a ________, I leave extra time when travelling to an unfamiliar venue.
Show the answer
Rule of thumb — A practical, approximate guide based on experience rather than an exact rule.
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Make it yours
Write one sentence using “Rule of thumb” about your own life.
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Does your sentence match this meaning?
A practical, approximate guide based on experience rather than an exact rule.
Compare: As a rule of thumb, I leave extra time when travelling to an unfamiliar venue.
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More ways to understand and use it
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When to use it
Use this expression when offering a useful starting point or rough method. Make clear that it may need adjustment for the particular situation.
More examples in context
- Her rule of thumb for a first draft is to put the main message near the beginning.
- This spacing guide is only a rule of thumb, so check how the finished page looks.
Usage note
Use a rule of thumb or as a rule of thumb. The plural is rules of thumb. It is an approximate guide, not a guarantee, official requirement or substitute for an exact calculation when one is needed.
A short conversation
A: How much space should I leave for the heading?
B: This example gives you a rule of thumb, but check the full page.
A: I will adjust it after previewing the layout.
One more practice question
How should you treat a rule of thumb?
A. As an approximate practical guide that may need adjustment.
B. As an exact requirement that can never have exceptions.
Check your answer
A. Approximation and practical experience are central to the expression.
Related lessons
Meaning and usage checked against Cambridge Dictionary. Explanations, examples and conversation are original.