📈 需求价格弹性计算器Price Elasticity of Demand Calculator
用中点（弧弹性）法由两组价格和需求量计算需求价格弹性，判断富有弹性、单位弹性或缺乏弹性，并比较价格变化前后的总收入。Calculate price elasticity of demand from two prices and quantities using the midpoint (arc) method, classify it as elastic, unit elastic or inelastic, and compare total revenue before and after.
使用说明与常见问题How-to & FAQ
「需求价格弹性计算器」是什么？What is the Price Elasticity of Demand Calculator tool?
用中点（弧弹性）法由两组价格和需求量计算需求价格弹性，判断富有弹性、单位弹性或缺乏弹性，并比较价格变化前后的总收入。Calculate price elasticity of demand from two prices and quantities using the midpoint (arc) method, classify it as elastic, unit elastic or inelastic, and compare total revenue before and after.
如何使用「需求价格弹性计算器」？How do I use the Price Elasticity of Demand Calculator tool?
在「需求价格弹性计算器」中，填写「原价格」、「新价格」、「原需求量」、「新需求量」等参数，结果会随输入实时计算并显示在下方。In the Price Elasticity of Demand Calculator: Fill in "Original price", "New price", "Original quantity", "New quantity"; results are recalculated instantly as you type.
为什么用中点法？Why the midpoint method?
简单百分比法从 A 到 B 和从 B 到 A 算出的弹性不同；中点法用两点的平均值作分母，结果与方向无关。下方也给出简单百分比法结果供对照。The simple percentage method gives different answers going from A to B than from B to A; the midpoint method divides by the average of the two points, so direction doesn't matter. The simple result is shown too for comparison.
弹性和收入有什么关系？How does elasticity relate to revenue?
缺乏弹性（|E| < 1）时涨价会增加总收入；富有弹性（|E| > 1）时涨价会减少总收入；单位弹性时总收入大致不变。When demand is inelastic (|E| < 1), raising the price raises revenue; when elastic (|E| > 1), raising it lowers revenue; at unit elasticity revenue stays about the same.
计算结果可以作为最终依据吗？Can I rely on the result?
「需求价格弹性计算器」按标准公式计算，结果仅供参考；实际金额以银行、券商或税务机关的规则和四舍五入方式为准。The Price Elasticity of Demand Calculator uses standard formulas and is for estimation only; actual figures depend on your bank, broker or tax authority's rules and rounding.
「需求价格弹性计算器」免费吗？需要注册吗？Is the Price Elasticity of Demand Calculator free? Do I need an account?
「需求价格弹性计算器」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 Price Elasticity of Demand 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.