SG 比重计算器（密度、质量与体积、水中称重）Specific Gravity Calculator (Density, Mass and Volume, Weighing in Water)

使用说明与常见问题How-to & FAQ

「比重计算器（密度、质量与体积、水中称重）」是什么？What is the Specific Gravity Calculator (Density, Mass and Volume, Weighing in Water) tool?

三种方法求比重 SG：由密度和参考密度（默认 4 °C 水 1000 kg/m³）；由质量和体积；或用阿基米德法（空气中重量 ÷ (空气中重量 − 水中重量)）。同时给出 g/cm³、lb/ft³ 密度，以及 API 度、波美度等换算和是否浮于水。本地处理。Three ways to get specific gravity: from density and a reference density (water at 4 °C, 1000 kg/m³, by default); from mass and volume; or by Archimedes (weight in air ÷ (weight in air − weight in water)). Also gives density in g/cm³ and lb/ft³, API gravity and Baumé degrees, and whether it floats in water. Processed locally.

如何使用「比重计算器（密度、质量与体积、水中称重）」？How do I use the Specific Gravity Calculator (Density, Mass and Volume, Weighing in Water) tool?

在「比重计算器（密度、质量与体积、水中称重）」中，填写「方法」、「密度」、「参考密度」、「质量 g」、「体积 cm³」等参数，结果会随输入实时计算并显示在下方。In the Specific Gravity Calculator (Density, Mass and Volume, Weighing in Water): Fill in "Method", "Density", "Reference density", "Mass g", "Volume cm³"; results are recalculated instantly as you type.

比重是什么？What is specific gravity?

物质密度与参考物质（通常是 4 °C 的水，1000 kg/m³）密度的比值，没有单位。比重小于 1 的物体在水中上浮。The ratio of a substance's density to that of a reference, usually water at 4 °C (1000 kg/m³). It has no units, and anything below 1 floats in water.

怎么用水中称重测比重？How does weighing in water work?

阿基米德原理：SG = 空气中重量 ÷ (空气中重量 − 水中重量)。重量差就是排开水的重量。例如 50 g 的石头在水中称 30 g，SG = 50 ÷ 20 = 2.5。By Archimedes, SG = weight in air ÷ (weight in air − weight in water); the difference is the weight of displaced water. A 50 g stone weighing 30 g in water has SG = 50 ÷ 20 = 2.5.

API 度怎么换算？How does API gravity convert?

API 度 = 141.5 ÷ SG − 131.5（60 °F）。水为 10°API，数值越大油越轻。API gravity = 141.5 ÷ SG − 131.5 at 60 °F. Water is 10°API, and higher numbers mean lighter oil.

能举个计算实例吗？Can you show a worked example?

例如在「比重计算器（密度、质量与体积、水中称重）」中填 密度 = 800，参考密度 = 1000，结果区显示：比重：0.8For example, entering Density = 800, Reference density = 1000 in the Specific Gravity Calculator (Density, Mass and Volume, Weighing in Water) gives: Specific gravity: 0.8

哪些输入会被检查？Which inputs are validated?

「比重计算器（密度、质量与体积、水中称重）」会检查这些输入——「密度」、「参考密度」、「质量 g」、「体积 cm³」、「空气中重量」：所选方式用到时必须填写，须大于 0；「水中重量」：所选方式用到时必须填写，须小于空气中重量（可为 0）；绝对值超过 10¹⁵ 的数也会被拒绝。不符合时结果区显示具体提示，不会给出数字。The Specific Gravity Calculator (Density, Mass and Volume, Weighing in Water) checks its inputs — "Density", "Reference density", "Mass g", "Volume cm³", "Weight in air": required when the chosen option uses it, must be greater than 0; "Weight in water": required when the chosen option uses it, must be less than the weight in air (0 allowed); numbers above 10¹⁵ in absolute value are rejected too. When a value fails, the result area names the problem instead of showing a number.

有哪些选项可以调整？What options can I adjust?

「比重计算器（密度、质量与体积、水中称重）」的设置：「方法」可选 密度、质量与体积、水中称重（默认 密度）；「密度」默认 800；「参考密度」默认 1000；「质量 g」默认 250；「体积 cm³」默认 100；「空气中重量」默认 50；「水中重量」默认 30。每次生成结果都按当前设置处理。Settings in the Specific Gravity Calculator (Density, Mass and Volume, Weighing in Water) — "Method": Density, Mass and volume, Weighing in water (default Density); "Density" default 800; "Reference density" default 1000; "Mass g" default 250; "Volume cm³" default 100; "Weight in air" default 50; "Weight in water" default 30. The result always uses the current settings.

计算结果可以用于作业或工程吗？Can I use the results for homework or engineering?

「比重计算器（密度、质量与体积、水中称重）」使用教科书标准公式（公式写在说明和常见问题中），适合学习和估算核对；涉及安全的工程设计请以规范和实测为准。The Specific Gravity Calculator (Density, Mass and Volume, Weighing in Water) uses standard textbook formulas (given in the description and FAQ), which is good for learning and checking estimates; for safety-critical engineering follow codes and measured values.

「比重计算器（密度、质量与体积、水中称重）」免费吗？需要注册吗？Is the Specific Gravity Calculator (Density, Mass and Volume, Weighing in Water) free? Do I need an account?

「比重计算器（密度、质量与体积、水中称重）」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Specific Gravity Calculator (Density, Mass and Volume, Weighing in Water) is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.