Investment Calculator

This investment calculator projects a starting amount plus regular monthly or yearly contributions forward at an expected rate of return. It shows the end balance, how much of it you actually paid in, how much is compound growth, and, if you set an inflation rate, what the whole thing is worth in today's money.

Unlike a plain compounding tool, the point here is the contributions. For most people the regular deposit does more work than the opening balance, and the year-by-year schedule underneath the result makes it obvious when growth finally overtakes the money you put in.

What each input really means

Input	What it is	Getting it right
Starting amount	What is invested on day one	Cash already in the account, so enter 0 if you are starting fresh
Contribution	What you add every period	Use the amount you will genuinely keep up, not the best month you ever had
Years to grow	How long before you touch it	The single most powerful input on this page
Expected return	Average annual growth	Broad stock indices have historically averaged roughly 7% a year after inflation over long periods, but with severe swings
Inflation	How fast prices rise	Around 2 to 3% is a common long-run planning figure

Why the rate here needs no compounding dropdown

Many investment calculators ask you to pick a compounding frequency, then quietly divide your rate by it, so "7% compounded monthly" actually grows 7.23% in a year. This calculator treats your figure as the effective annual return: twelve monthly steps compound to exactly 7%, because each step uses the twelfth root of 1.07 rather than 7 ÷ 12. Enter 7% and you get 7% a year, with no hidden uplift. If you specifically want to explore nominal rates and compounding frequencies on a lump sum, the compound interest calculator is built for exactly that.

Four things that change the outcome most

1. 1Time, by a wide margin

   Compound growth is exponential, so the last decade of a long plan adds more than the first two combined. Push the years field from 20 to 30 and watch the growth share climb, because the extra ten years usually adds more than doubling the monthly contribution would.

2. 2The contribution, not the starting pot

   Set the starting amount to 0 and load the "Start from zero" example. A modest deposit kept up for thirty years still builds a substantial balance, because every instalment gets its own run of compounding.

3. 3Paying in at the start of the period

   Switching "Contribute at the" to the start of each period gives every single contribution one extra period of growth. It is a small change on one deposit and a meaningful one across 360 of them.

4. 4Raising the contribution each year

   Most people can save a little more as income rises. Put 3% in "Raise contribution / year" and the schedule steps the instalment up annually, often the most realistic assumption on the whole page.

Nominal versus real: read the today's-money column

A projected balance decades out is quoted in future dollars, which buy less than today's. Enter an inflation rate and the last column of the schedule restates every year's balance in today's purchasing power. At 3% inflation, money loses roughly half its value over 24 years, so a headline figure that looks life-changing in 2050 terms may be merely comfortable in today's terms. Planning against the real column is the honest way to do it.

Where the money can actually go

The calculator is deliberately investment-agnostic: it does not care whether the return comes from an index fund, a bond ladder, a certificate of deposit or rental property. What differs between those is risk, the spread of outcomes around the average. A CD's 4% is close to guaranteed; a stock index's long-run average comes with years that finish deeply negative. Two plans with the same expected return are not equally safe, and no calculator can show you that difference. Match the rate you type in to the risk you are genuinely willing to hold through a bad year.