平均修复时间（Mean time to recovery，MTTR），是描述产品由故障状态转为工作状态时修理时间的平均值。产品的特性决定了平均值的长短，例如：硬盘错误的自动修复机制，又或整个机场的电脑系统发生故障。

在工程学，「平均修复时间」是衡量产品维修性的值。因此，这个值在维护合约里很常见，并以之作为服务收费的准则。举例说：当一个团体的电脑系统发生故障，一份要求在24小时内把系统修复的合约，一般会比一份允许系统在一星期内修复的合约要来得昂贵。然而，这个「平均修复时间」的值并不表示系统必然会在指定的时间内恢复，因为那只是一个平均时间值。若要表示在指定时间内恢复系统，则要使用「最大修复时间」。

MTTR is an abbreviation that has several different expansions, with greatly differing meanings. It is wise to spell out exactly what is meant by the use of this abbreviation, rather than assuming the reader will know which is being assumed. The M can stand for any of minimum, mean or maximum, and the R can stand for any of recovery, repair, respond, or restore. The most common, mean, is also subject to interpretation, as there are many different ways in which a mean can be calculated.