🔲 周长计算器Perimeter Calculator
计算正方形、矩形、三角形、圆、椭圆、梯形、平行四边形和正多边形的周长。Perimeter of squares, rectangles, triangles, circles, ellipses, trapezoids, parallelograms and regular polygons.
使用说明与常见问题How-to & FAQ
「周长计算器」是什么？What is the Perimeter Calculator tool?
计算正方形、矩形、三角形、圆、椭圆、梯形、平行四边形和正多边形的周长。Perimeter of squares, rectangles, triangles, circles, ellipses, trapezoids, parallelograms and regular polygons.
如何使用「周长计算器」？How do I use the Perimeter Calculator tool?
在「周长计算器」中，填写「形状」、「a」、「b」、「c」、「d」等参数，结果会随输入实时计算并显示在下方。In the Perimeter Calculator: Fill in "Shape", "a", "b", "c", "d"; results are recalculated instantly as you type.
计算精度如何？How precise are the results?
「周长计算器」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 Perimeter Calculator uses double-precision floating point (about 15–16 significant digits); very large or very small values may lose precision.
「周长计算器」免费吗？需要注册吗？Is the Perimeter Calculator free? Do I need an account?
「周长计算器」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 Perimeter Calculator is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.