A 5% nominal return with 3% inflation is a 1.94% real return, not 2% — the Fisher equation divides the ratios because both compound. The tool also shows what an amount actually buys after N years, the number a savings account statement never prints.
It pairs with the existing inflation calculator: that one projects how prices erode cash; this one strips inflation out of a return you were promised.
Frequently asked questions
When is the naive subtraction wrong by a lot?
With high numbers: 50% return against 45% inflation is 3.45% real, not 5%. At everyday 2-8% rates the gap is small but real.
Which inflation number should I use?
Your personal basket matters more than the CPI headline — rent, education and healthcare usually outrun the average.
中文说明
名义收益 5%、通胀 3%，真实收益是 1.94% 而不是 2%——费雪方程算的是比值，因为两者都在复利。工具还会算出这笔钱 N 年后实际能买什么，这是存折上永远不会印的数字。
它与现有的通胀计算器互补：那个算现金购买力如何被侵蚀，这个把承诺给你的收益率剥掉通胀。
常见问题
简单相减什么时候错得多？
数字大的时候：收益 50%、通胀 45%，真实收益是 3.45% 而非 5%。日常 2–8% 的区间误差小但确实存在。
该用哪个通胀数字？
你自己的消费篮子比 CPI 头条更重要——房租、教育、医疗通常跑赢平均。