rule of thumb

Related to rule of thumb: Rule of thirds

rule of thumb

An approximation; a suggested method or guideline. A good rule of thumb is to plant your seedlings around the end of May.
See also: of, rule, thumb
Farlex Dictionary of Idioms.

rule of thumb

a general principle developed through experiential rather than scientific means. 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.
See also: of, rule, thumb
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

rule of thumb

A rough and useful principle or method, based on experience rather than precisely accurate measures. For example, His work with the youth group is largely by rule of thumb. This expression alludes to making rough estimates of measurements by using one's thumb. [Second half of 1600s]
See also: of, rule, thumb
The American Heritage® Dictionary of Idioms by Christine Ammer.

a rule of thumb

COMMON A rule of thumb is a general rule about something which is right in most cases. As a rule of thumb, drink a glass of water or pure fruit juice every hour you are travelling. A good rule of thumb for any type of studio photography is to use no more light sources than are strictly necessary. Note: This expression probably dates back to the use of the first joint of the thumb as a unit of measurement.
See also: of, rule, thumb
Collins COBUILD Idioms Dictionary, 3rd ed.

rule of thumb

a broadly accurate guide or principle, based on experience or practice rather than theory.
1998 New Scientist The best forecast of tomorrow's weather in any one place often comes not from a supercomputer, but from the rule of thumb that says: tomorrow it will be similar to today.
See also: of, rule, thumb
Farlex Partner Idioms Dictionary

a rule of ˈthumb

a quick, practical, but not exact, way of measuring or calculating something: As a rule of thumb you need a litre of paint to every 12 square metres of wall.This phrase may come from the fact that people often used their thumbs to estimate measurements.
See also: of, rule, thumb
Farlex Partner Idioms Dictionary

rule of thumb

A rough measure or method, without precise mathematical or scientific basis. This term, which probably alluded to using one’s thumb as an approximate measuring device, has been around since the seventeenth century and made it into James Kelly’s collection of Scottish proverbs (1721): “No rule so good as rule of thumb, if it hit. But it seldome hits!” Some individuals have pointed to the “rule” proposed in 1782 by an English judge, Francis Buller, who proclaimed that men had the right to beat their wives provided that the stick used was no thicker than the husband’s thumb. Misinterpretation linked it to the cliché, which is about a century older and today is never used in this context.
See also: of, rule, thumb
The Dictionary of Clichés by Christine Ammer
See also:
  • a rule of thumb
  • rule with a velvet glove
  • bite (one's) thumb at
  • exception
  • be the exception that proves the rule
  • rule the school
  • unwritten
  • unwritten law
  • unwritten rule
  • on the bench
References in periodicals archive
A useful rule of thumb emerges if the estimates of the constant and the coefficient do not vary over time.
An unstable Okun's law, not the best rule of thumb
Though it did not attract much attention at the time, the particular rule of thumb proposed by Poole in 1971 is of interest in that it incorporated both a reaction of the interest rate to real economic activity (specifically the deviation of the unemployment rate from the Federal Reserve's estimate of the full employment rate at the time), as well as a nominal variable in a way that would ensure price stability over the long run.
Economic projections and rules of thumb for monetary policy
And for all the talk about belt-tightening in newsrooms, every circulation group is comfortably within the rule of thumb that newsroom expenses should account for 14% to 15% of total costs.
Newspapers All Thumbs On 'Rules'
We show in the present study that this arbitrary rule of thumb for approximating M is unnecessary, as an empirical method (Hoenig, 1983) provides an analogous estimate based on a substantial data set.
Comparison of two approaches for estimating natural mortality based on longevity *
Diversity--the financial portfolio kind--is certainly an investing rule of thumb. And often mutual funds, generally less volatile than stocks, are a first investment choice.
Mutual funds get in the game
The company may use some sort of general "rule of thumb" or management's "best estimate" to determine that fair value and may or may not come up with a reasonable measurement.
'Cheap stock' questions can plague growing companies: a rule of thumb or management's best estimate aren't good enough anymore. But the a new AICPA Practice Aid unravels some of the mysteries and exposes the pitfalls
As a rule of thumb, medical professionals X-ray pregnant women only "when there is a reasonable expectation of a health benefit," says S.
Unsettling association: dental X rays linked to low-birth-weight babies
"Follow the money" has long been a useful rule of thumb for observers of politics, but it's never been quite as easy as it is today.
Source
As a rule of thumb, optimum sand conditioning can be realized when the ratio of molding sand compactability to moisture content is between 10.5:1 and 12:1 in iron foundries (the ratio cannot be applied to other materials).
Feeling out sand conditioning
Yes, a quick rule of thumb matches the diameter of the fan with the largest dimension of a room.
Sizing a ceiling fan
A rule of thumb with flowers is that the larger the seed, the longer they will tend to remain viable.
How to do it
The general rule of thumb is one metric tonne of manure will produce 15 cubic metres of methane.
Firm turns sludge, road kill into profit
Again, as a rule of thumb, the best time to prune trees is during their dormant season.
Tree doctor
A RULE OF thumb is a simple relationship that allows us to effortlessly "put in the numbers" at the starting point of an estimate.
Rules of thumb I have known and loved: while no substitute for good design practices, in certain situations they can be useful
Our training leads us to search for the formula, the rule of thumb or the checklist.
How to value an accounting firm