Base runs (BsR) is a baseball statistic invented by sabermetrician David Smyth to estimate the number of runs a team "should have" scored given their component offensive statistics, as well as the number of runs a hitter or pitcher creates or allows. It measures essentially the same thing as Bill James' runs created, but as sabermetrician Tom M. Tango points out, base runs models the reality of the run-scoring process "significantly better than any other run estimator".

Base runs has multiple variations, but all take the form

Smyth detailed the following forms of the statistic:

The simplest, uses only the most common batting statistics

A = H + BB - HR

B = (1.4 * TB - .6 * H - 3 * HR + .1 * BB) * 1.02

C = AB - H

D = HR