Initial investment, contributions, return, and time horizon are enough for a useful first pass. Fees, inflation, ages, and contribution growth are there when you want a more realistic scenario.
If you are unsure, keep the defaults and start simple.
Quick start
Start with your compound interest assumptions
Enter the core numbers first, then refine the scenario with fees, inflation, and compounding details if you want a more realistic result.
Results
Your compound growth
Values shown in nominal dollars.
Understand this compound growth result
Main takeaway
A quick read on what this estimate means and the next realism check worth trying.
Results are estimates, not guarantees. Returns, inflation, fees, and contribution increases are user assumptions. Actual market performance will vary.
Optional charts
How compounding builds over time
Optional visuals if you want to see how compound growth, contributions, and fees shape the result over time.
See charts
Detail
Optional planner detail
Open this only if you want a year-by-year breakdown of how the balance changes.
See yearly detail
| Year | Age | Starting balance | Contributions | Growth earned | Fees deducted | Ending balance | Inflation-adjusted ending balance |
|---|
Optional learning
Compound interest explained in plain English
Optional deeper reading if you want more context around compound interest, recurring contributions, fees, inflation, and common planning questions.
Read guide
What is compound interest?
Compound interest means your investment can earn growth on both the money you put in and the returns already earned. Over long periods, that snowball effect can become one of the biggest drivers of portfolio growth.
Why recurring contributions matter
Regular monthly, biweekly, or annual contributions can meaningfully increase long-term results because each new deposit gets its own chance to compound over time.
How fees and inflation affect investment growth
Even small annual fees reduce the amount left invested, which lowers future compound growth. Inflation also reduces future purchasing power, so a large future balance may still buy less than it does today.
Compound interest example
If you invest $10,000 and add $500 per month, compound growth can have a much larger impact over decades than most people expect, especially once returns start building on earlier gains.
What to focus on first
For most first-pass scenarios, the biggest levers are time invested, contribution consistency, and whether your return, fee, and inflation assumptions are realistic.
How to use this for retirement planning
Use this calculator to pressure-test your contribution pace and long-term compound growth assumptions before moving into a fuller retirement plan.
Common mistakes to avoid
Common mistakes include assuming guaranteed returns, skipping fees, ignoring inflation, or using a contribution schedule that does not match how you actually invest.
Open the FAQ
What is compound interest?
Compound interest means your money can earn returns on both your original investment and the gains already earned, which is why long timelines can lead to much stronger growth.
How often should I contribute?
The best schedule is usually the one you can sustain consistently. Monthly and biweekly contributions are common because they let new money start compounding sooner.
Does this calculator include inflation?
Yes. You can turn on today’s-dollar results to see what the future balance may be worth after inflation.
How do fees affect long-term growth?
Fees reduce the amount of return left invested, which lowers both today’s gains and the future compounding of those gains.
Does this compound interest calculator include contributions?
Yes. You can model monthly, biweekly, or annual contributions, optionally increase those contributions over time, and add one future lump sum.
Why should I adjust for inflation?
Inflation adjustment helps you understand what a future balance may be worth in today’s dollars, which can be more useful for retirement or spending planning.