长打率(英文：Slugging Percentage)为一般衡量长打能力的数字。字面上的解释应该是「出现长打的机率」，但事实上，更深层的意义是「每一次打击可以贡献几个垒包」。

长打率=垒打数÷打数

以Albert Pujols为例：

Albert Pujols在2006年球季535打数中，击出94支一垒安打、33支二垒安打、1支三垒安打以及49支全垒打。

他的长打率即为：[(1×94)+(2×33)+(3×1)+(4×49)]÷535=359÷535≒0.671

我们通常四舍五入取近似值到小数点后第三位。

In baseball statistics, slugging percentage (abbreviated SLG) is a popular measure of the power of a hitter. It is calculated as total bases divided by at bats:

where AB is the number of at-bats for a given player, and 1B, 2B, 3B, and HR are the number of singles, doubles, triples, and home runs, respectively. Walks are specifically excluded from this calculation. The name is a misnomer, as the statistic is not a percentage but a scale of measure whose computed value is a rational number in the interval .