Rule of thumb
Meaning: a way of calculating something, which is not exact but which will help you to be correct enough, a general principle developed through experiential rather than scientific means
Example: As a rule of thumb, I move my houseplants outside in May. Going by a rule of thumb, we stop for gas every 200 miles when we are traveling.
Example: As a rule of thumb, I move my houseplants outside in May. Going by a rule of thumb, we stop for gas every 200 miles when we are traveling.
