Meanings
plural rules of thumb · alternative rule-of-thumb
- idiomaticA general guideline, rather than a strict rule; an approximate measure or means of reckoning based on experience or common knowledge.
The usual rule of thumb says that to calculate when an investment will double, divide 70 by the interest rate.
3 more examples
Here's a good rule of thumb: Too clever is dumb.
c. 1935, Ogden Nash, “Reflection on Ingenuity”, in Verses from 1929 On, published 1959Since it is impossible to second-guess what a user will want to look up, there is a general lexicographical rule of thumb to err on the side of inclusion.
2016, James Lambert, “Ornithonymy and Lexicographical Selection Criteria”, in International Journal of Lexicography, volume 30, number 1, pages 39–62At the risk of making a broad generaliation, you can say that the general rule of thumb is that Ghoti dishes are a bit sweet, while Bangal dishes are spicy, have a strong chilli element and are savoury.
2016, Kalyan Karmakar, “Sweet Home Kolkata”, in The Travelling Belly: Eating Through India’s By-Lanes, Gurgaon, Haryana: Hachette India, →ISBN, page 29 - attributiveusually hyphenatedApproximated, guesstimated.
I made a quick, rule-of-thumb estimate of the manhours required for the job.
Synonyms & antonyms
nouna rule or principle that provides guidance to appropriate behavior
Synonym sets from Open English WordNet, CC BY 4.0.
Origin
Attested since 1658. Of uncertain origin, but probably based on the use of the thumb as reference for various measurements. For instance, one theory notes that the inch originated as the distance between the base of the thumbnail and the first joint, another notes the practice of approximating the general direction of the wind by wetting the thumb then raising it in the air. A third theory notes that English royal banquet plate setters used the distance of their thumbs to equally space each plate from the table edge. The erroneous claim that the term referred to the maximum thickness of a stick with which it was permissible for a man to beat his wife has appeared in The Washington Post and Time; it may originate from Del Martin's 1976 book Battered Wives.
Full word history & related roots →Translations
Arabic قَاعِدَة عَامَّة
- قَاعِدَة عَامَّةgeneral guideline rather than a strict rule
Catalan regla general
- regla generalgeneral guideline rather than a strict rule
Chinese Mandarin 拇指規則 /拇指规则, 概測法 /概测法
- 拇指規則 /拇指规则 (mǔzhǐ guīzé)general guideline rather than a strict rule
- 概測法 /概测法 (gàicèfǎ)general guideline rather than a strict rule
- 經驗法則 /经验法则 (jīngyàn fǎzé)general guideline rather than a strict rule
- 一般規則 /一般规则 (yībān guīzé)general guideline rather than a strict rule
Danish tommelfingerregel
- tommelfingerregelgeneral guideline rather than a strict rule
Dutch vuistregel
- vuistregelgeneral guideline rather than a strict rule
Finnish nyrkkisääntö, peukalosääntö
- nyrkkisääntögeneral guideline rather than a strict rule
- peukalosääntögeneral guideline rather than a strict rule
French règle générale, au doigt mouillé
- règle généralegeneral guideline rather than a strict rule
- au doigt mouillégeneral guideline rather than a strict rule
- au pifgeneral guideline rather than a strict rule
German Faustregel, Daumenregel
- Faustregelgeneral guideline rather than a strict rule
- Daumenregelgeneral guideline rather than a strict rule
Greek πρακτικός κανόνας, βασικός κανόνας
- πρακτικός κανόνας (praktikós kanónas)general guideline rather than a strict rule
- βασικός κανόνας (vasikós kanónas)general guideline rather than a strict rule
Hebrew כְּלַל אֶצְבַּע
- כְּלַל אֶצְבַּע (klál étsba)general guideline rather than a strict rule
Hungarian ökölszabály
- ökölszabálygeneral guideline rather than a strict rule
Icelandic þumalputtaregla
- þumalputtareglageneral guideline rather than a strict rule
Italian a lume di naso
- a lume di nasogeneral guideline rather than a strict rule
Japanese 大体の目安, 目の子算
- 大体の目安 (daitai no meyasu)general guideline rather than a strict rule
- 目の子算 (me no kozan)general guideline rather than a strict rule
Norwegian Bokmål tommelfingerregel
- tommelfingerregelgeneral guideline rather than a strict rule
Portuguese heurística, macete
- heurísticageneral guideline rather than a strict rule
- macetegeneral guideline rather than a strict rule
- manhageneral guideline rather than a strict rule
Russian практи́ческое пра́вило, эмпири́ческий приём
- практи́ческое пра́вило (praktíčeskoje právilo)general guideline rather than a strict rule
- эмпири́ческий приём (empiríčeskij prijóm)general guideline rather than a strict rule
- пра́вило большо́го па́льца (právilo bolʹšóvo pálʹca)general guideline rather than a strict rule
Spanish regla / pauta general
- regla / pauta generalgeneral guideline rather than a strict rule
Swedish tumregel
- tumregelgeneral guideline rather than a strict rule
Turkish pratik kural
- pratik kuralgeneral guideline rather than a strict rule
Cite this entry
rule of thumb. (n.d.). In WatkinsX Dictionary. Retrieved November 5, 2026, from https://dictionary.watkinsx.com/word/rule%20of%20thumb
“rule of thumb.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/rule%20of%20thumb. Accessed November 5, 2026.
WatkinsX Dictionary, s.v. “rule of thumb,” accessed November 5, 2026, https://dictionary.watkinsx.com/word/rule%20of%20thumb.
Source: rule of thumb on Wiktionary, CC BY-SA 4.0.