Meaning & use
good rule of thumb
Last updated
Meanings
phrasecountable
A simple, practical way of judging something that is usually right, though not exact in every case.
Grammar: Usually used with 'a' or 'the': as a good rule of thumb, ...
Patterns
- a good rule of thumb is to do something
- as a good rule of thumb
- a good rule of thumb for something
As a good rule of thumb, aim to save about ten percent of your monthly pay.
A good rule of thumb is to wait twenty-four hours before answering an angry email.
There is no exact number, but a good rule of thumb for this recipe is one egg per person.
phrasecountable
A rough method or measurement that gives a close enough answer for everyday purposes.
Grammar: Often followed by 'for' plus the thing being measured or judged.
Patterns
- a good rule of thumb for something
- a good rule of thumb for doing something
A good rule of thumb for painting is one liter of paint for every twelve square meters.
For judging distance at sea, sailors use a good rule of thumb based on the horizon.
Word forms
| plural | good rules of thumb |
|---|
Common combinations
- as a good rule of thumb
- As a good rule of thumb, leave the house ten minutes earlier than you think you need to.
- a good rule of thumb is to ...
- A good rule of thumb is to reread your message before you hit send.
- a good rule of thumb for ...
- Here is a good rule of thumb for deciding how much rice to cook.
- a useful rule of thumb
- Experienced teachers develop a useful rule of thumb for spotting a tired class.
- follow a rule of thumb
- If you follow a simple rule of thumb, budgeting becomes much easier.
Synonyms and how they differ
- guideline
- 'Guideline' sounds more official and is often written down, while a rule of thumb is a rough personal method you carry in your head.
- rule
- A rule is usually firm and must be obeyed; a rule of thumb is only a helpful approximation that you may ignore.
- approximation
- An approximation is a technical, neutral word for an inexact figure, but it does not carry the idea of practical everyday advice.
Opposites
Word family
- rule of thumb phrase
- The shorter form of the same expression, used when no judgment about its quality is being made.
- thumb noun
- The short thick finger on the side of your hand, the body part that gave this expression its name.
Commonly confused: good rule of thumb or rule of the thumb? good rule of thumb or golden rule?
good rule of thumb vs rule of the thumb
This is a common mistake: the fixed expression uses 'of thumb', not 'of the thumb'.
good rule of thumb vs golden rule
A golden rule is a very important principle you should always follow, while a good rule of thumb is only a rough, usually reliable guide.
Practice
Which sentence uses the expression correctly?
Choose one answer.
The fixed form is 'a good rule of thumb', with 'of thumb' and a singular 'rule'. Option 1 adds 'the', which is wrong here; option 2 drops the article 'a'; option 3 wrongly makes both words plural.
Make it your own
Write a sentence using “good rule of thumb”, then check it and compare it with the examples above.