提丢斯-波得定则（Titius-Bode law）是关于太阳系中行星轨道半径的一个简单的几何学规则。

它是在1766年时，由德国的一位大学教授约翰∙达尼拉∙提丢斯所提出，后来被柏林天文台的台长约翰·波得（Johann Elert Bode）归纳成了一个经验公式来表示。

这个公式可以表述为：

其中

现代的公式把a作为行星到太阳的平均距离（天文单位）：

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The Titius–Bode law (sometimes termed just Bode's law) is a hypothesis that the bodies in some orbital systems, including the Sun's, orbit at semi-major axes in a function of planetary sequence. The formula suggests that, extending outward, each planet would be approximately twice as far from the Sun as the one before. The hypothesis correctly anticipated the orbits of Ceres (in the asteroid belt) and Uranus, but failed as a predictor of Neptune's orbit and has since been discredited further. It is named for Johann Daniel Titius and Johann Elert Bode.