📦 长方体计算器（体积、表面积、体对角线、面对角线）Rectangular Prism Calculator (Volume, Surface Area, Space and Face Diagonals)
由长、宽、高求长方体（立方体为特例）的体积 V = lwh、表面积 2(lw + lh + wh)、体对角线 √(l2 + w2 + h2) 和三个面的对角线；以厘米为单位时还给出容积升数。本地处理。From length, width and height get the volume V = lwh, surface area 2(lw + lh + wh), space diagonal √(l2 + w2 + h2) and the three face diagonals of a rectangular prism (a cube is a special case); in centimetres it also gives the capacity in litres. Processed locally.
使用说明与常见问题How-to & FAQ
「长方体计算器（体积、表面积、体对角线、面对角线）」是什么？What is the Rectangular Prism Calculator (Volume, Surface Area, Space and Face Diagonals) tool?
由长、宽、高求长方体（立方体为特例）的体积 V = lwh、表面积 2(lw + lh + wh)、体对角线 √(l2 + w2 + h2) 和三个面的对角线；以厘米为单位时还给出容积升数。本地处理。From length, width and height get the volume V = lwh, surface area 2(lw + lh + wh), space diagonal √(l2 + w2 + h2) and the three face diagonals of a rectangular prism (a cube is a special case); in centimetres it also gives the capacity in litres. Processed locally.
如何使用「长方体计算器（体积、表面积、体对角线、面对角线）」？How do I use the Rectangular Prism Calculator (Volume, Surface Area, Space and Face Diagonals) tool?
在「长方体计算器（体积、表面积、体对角线、面对角线）」中，填写「长」、「宽」、「高」、「单位」等参数，结果会随输入实时计算并显示在下方。In the Rectangular Prism Calculator (Volume, Surface Area, Space and Face Diagonals): Fill in "Length", "Width", "Height", "Units"; results are recalculated instantly as you type.
长方体的体对角线怎么求？How do I find the space diagonal?
d = √(l2 + w2 + h2)。4 * 3 * 12 的长方体：√(16 + 9 + 144) = √169 = 13。d = √(l2 + w2 + h2). For a 4 * 3 * 12 prism: √(16 + 9 + 144) = √169 = 13.
能举个计算实例吗？Can you show a worked example?
例如在「长方体计算器（体积、表面积、体对角线、面对角线）」中填 长 = 4，宽 = 3，高 = 2，结果区显示：体积：24；表面积：52For example, entering Length = 4, Width = 3, Height = 2 in the Rectangular Prism Calculator (Volume, Surface Area, Space and Face Diagonals) gives: Volume: 24; Surface area: 52
哪些输入会被检查？Which inputs are validated?
「长方体计算器（体积、表面积、体对角线、面对角线）」会检查这些输入——「长」：必须填写，须大于 0且不大于 1,000,000,000；「宽」：必须填写，须大于 0且不大于 1,000,000,000；「高」：必须填写，须大于 0且不大于 1,000,000,000；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 Rectangular Prism Calculator (Volume, Surface Area, Space and Face Diagonals) checks its inputs — "Length": required, must be more than 0 and at most 1,000,000,000; "Width": required, must be more than 0 and at most 1,000,000,000; "Height": required, must be more than 0 and at most 1,000,000,000; 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?
「长方体计算器（体积、表面积、体对角线、面对角线）」的设置：「长」默认 4；「宽」默认 3；「高」默认 12；「单位」可选 无单位、厘米、米 m、英寸、英尺（默认 无单位）。每次生成结果都按当前设置处理。Settings in the Rectangular Prism Calculator (Volume, Surface Area, Space and Face Diagonals) — "Length" default 4; "Width" default 3; "Height" default 12; "Units": 5 choices. The result always uses the current settings.
计算精度如何？How precise are the results?
「长方体计算器（体积、表面积、体对角线、面对角线）」使用 JavaScript 双精度浮点数（约 15–16 位有效数字）；极大或极小的数值可能存在精度误差。The Rectangular Prism Calculator (Volume, Surface Area, Space and Face Diagonals) uses double-precision floating point (about 15–16 significant digits); very large or very small values may lose precision.
「长方体计算器（体积、表面积、体对角线、面对角线）」免费吗？需要注册吗？Is the Rectangular Prism Calculator (Volume, Surface Area, Space and Face Diagonals) free? Do I need an account?
「长方体计算器（体积、表面积、体对角线、面对角线）」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 Rectangular Prism Calculator (Volume, Surface Area, Space and Face Diagonals) is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.