rule of thumb

noun phrase

1

: a method of procedure based on experience and common sense

2

: a general principle regarded as roughly correct but not intended to be scientifically accurate

Examples of rule of thumb in a Sentence

Recent Examples on the Web

My rule of thumb is to pack two pairs—and never more than three. — Lydia Mansel, Travel + Leisure, 24 Sep. 2026

When to Harvest Onions A good rule of thumb for when to harvest onions is to wait until half of the leaves have died back. — Rita Pelczar, Better Homes & Gardens, 15 Sep. 2026

But for the moment, the best rule of thumb is to get the room as dark as possible, these studies suggest. — Veronique Greenwood, Time, 11 Sep. 2026

Broadly, the rule of thumb is to drink it during periods of intense competition (to allow for muscle recovery) while avoiding it during periods of training (to promote muscle development). — Jacob Whitehead, New York Times, 8 Sep. 2026

Word History

First Known Use

circa 1658, in the meaning defined at sense 1

Rhymes for rule of thumb

• abomasum
• become
• checksum
• humdrum
• income
• outcome
• pisum
• succumb
• therefrom
• wherefrom
• bum
• chum

Kids Definition

rule of thumb

1

: a method based on experience and common sense

2

: a general principle that is roughly correct