a general or approximate principle, procedure, or rule based on experience or practice, as opposed to a specific, scientific calculation or estimate.
2.
a rough, practical method of procedure.
Origin
1685-95
Examples from the web for rule of thumb
There is a simple rule of thumb that can be applied toward multiple solutions: don't expend energy in order to dissipate energy.
The rule of thumb was that the final exam on average dropped a student between one and two letter grades.
The rule of thumb is the higher the value, the darker the color.
And another rule of thumb: whenever beliefs get involved, don't trust anyone.
Everybody understands that, as a rule of thumb, more school means a bigger paycheck.
Twelve to fifteen books over a fifteen-week semester used to be the rule of thumb at selective colleges.
As a rule of thumb, lighter roasts are more acidic, while dark roasts are more bitter.
Another rule of thumb used to prevail among the better university presses.
The scientific rule of thumb is that one can never blame any one weather event on any single cause.
The rule of thumb is that when the two differ, go with the payroll survey.
British Dictionary definitions for rule of thumb
rule of thumb
noun
1.
a rough and practical approach, based on experience, rather than a scientific or precise one based on theory
(as modifier): a rule-of-thumb decision
rule of thumb in Culture
rule of thumb definition
A practical principle that comes from the wisdom of experience and is usually but not always valid: “When playing baseball, a good rule of thumb is to put your best hitter fourth in the batting order.”
Idioms and Phrases with rule of thumb
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 ]