Guesstimate is an informal English portmanteau of guess and estimate, first used by American statisticians in 1934[1] or 1935.
A guesstimate may be a first rough approximation pending a more accurate estimate, or it may be an educated guess at something for which no better information will become available.
The word may be used in a pejorative sense if information for a better estimate is available but ignored.
[7][8] Guesstimation techniques are used: Lawrence Weinstein and John Adam's 2009 book Guesstimation: Solving the World's Problems on the Back of a Cocktail Napkin, based on the course "Physics on the Back of an Envelope" at Old Dominion University, promotes guesstimation techniques as a useful life skill.
It includes many worked examples of guesstimation, including estimating the total number of miles that Americans drive in a year (about 2 trillion)[12] and the amount of high-level nuclear waste that a 1 GW nuclear power plant produces in a year (about 60 tons).