A cost estimate is the approximation of the cost of a program, project, or operation. The cost estimate is the product of the cost estimating process. The cost estimate has a single total value and may have identifiable component values.

A problem with a cost overrun can be avoided with a credible, reliable, and accurate cost estimate. A cost estimator is the professional who prepares cost estimates.

There are different types of cost estimators, whose title may be preceded by a modifier, such as building estimator, or electrical estimator, or chief estimator.

Other professionals such as quantity surveyors and cost engineers may also prepare cost estimates or contribute to cost estimates. In the US, according to the Bureau of Labor Statistics, there were 185,400 cost estimators in 2010. There are around 75,000 professional quantity surveyors working in the UK.