标准状况（英语：standard temperature and pressure, STP，标准温度与标准压力），简称「标况」。由于地表各处的温度、压力皆不同，即使是同一地点的温度压强也随测量时间不同而相异，因此为研究方便，制定出描述物质特征的标准状况：

历史上由巴黎制定的通行欧洲的旧制标准如下：

在化学和生物化学中另外还包括定义的观察反应物浓度，一般情况下为1mol/L（1 M）。在生物化学中只有质子例外（H）。限定pH为7，即10 mol/l H离子浓度用于准生理条件描述，肌体条件，细胞内部条件等。

Standard conditions for temperature and pressure are standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data. The most used standards are those of the International Union of Pure and Applied Chemistry (IUPAC) and the National Institute of Standards and Technology (NIST), although these are not universally accepted standards. Other organizations have established a variety of alternative definitions for their standard reference conditions.