Comprehensive Guide
Learn more in our Investing Guide.
How it works
investment return calculator takes your inputs and produces future value, total contributed, investment growth, in today's dollars, growth multiple. Project what your portfolio grows to with regular contributions and reinvested returns, with a breakdown of invested vs growth. You provide 6 inputs: Current portfolio value (currency, in dollars) (default: 25000 dollars); Monthly contribution (currency, in dollars) (default: 750 dollars); Expected annual return (percent, in percent) (default: 7 percent); Time horizon (years, in years) (default: 20 years); Inflation rate (percent, in percent) (default: 0 percent); Annual contribution increase (percent, in percent) (default: 0 percent). The calculator returns 5 outputs: Future value (the primary result); Total contributed (a secondary output); Investment growth (a secondary output); In today's dollars (a supplementary figure); Growth multiple (a supplementary figure). Investment calculations rest on a few variables — principal, return rate, time, and compounding — but their interaction is non-linear enough that intuition alone gets the answer wrong more often than not. This tool runs the real formula with your inputs and shows the numbers that matter, not the rounded approximations from a textbook. The underlying formula: FV = Σ (contributions compounded monthly) + initial balance compounded With the default values, future value is computed from the interaction of every input field — change any one of them and the result updates immediately, so you can stress-test different scenarios without re-entering the whole form. Adjust the inputs to match your real financial situation. The defaults are realistic starting points, but every person's circumstances differ — your actual income, expenses, rates, and timelines will produce a different answer. Use the tool iteratively: start with the defaults, then change one variable at a time to see which factor has the largest impact on your outcome.Formula
FV = Σ (contributions compounded monthly) + initial balance compounded
Tips
- Test your plan at 5% and 8% — the range between them is the honest forecast band.
- Annual increases of 2-4% model raises and compound into dramatically larger endings.
- Look at the today's-dollars line for goals; nominal numbers flatter the future.
- Re-run after every significant income or expense change.
Frequently asked questions
What is a realistic investment return assumption?
A diversified stock portfolio has historically returned 7-9% before inflation and 4-6% after; bonds less. For a 10+ year horizon, 7% before inflation is the common conservative planning number; 5% after inflation matches real purchasing-power goals.
How do contributions affect returns?
At a 7% return over 20 years, roughly 40% of the final value typically comes from contributions and 60% from growth — but that ratio shifts hard with the horizon. The chart shows both lines year by year, making the compounding story visual.
What is a growth multiple?
The final value divided by the total you contributed. A 2.5x multiple means the market roughly matched what you put in. Long horizons and high contribution growth raise the multiple; short ones keep it near 1.
Does this calculator model taxes?
No — it projects gross growth. Tax-advantaged accounts (401(k), IRA, HSA) keep the full projection; taxable accounts owe capital gains on the growth slice. Pair it with the Capital Gains Tax calculator for the after-tax version.