Future Value Calculator
Calculate how much your investment will be worth in the future with compound interest.
| Rate | FV (Principal Only) | FV of Payments | Total FV | Total Interest | Return % |
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Calculate how much a lump sum plus optional periodic contributions will grow to over time, with compound interest at any compounding frequency.
How Future Value Calculator Works
The future value of a lump sum uses the standard compound growth formula: FV = PV × (1 + r/n)^(n×t), where PV is your starting principal, r is the annual interest rate, n is the compounding frequency per year, and t is the number of years. This is the same formula behind everything from savings accounts to long-term investment projections.
If you also enter periodic contributions, the calculator separately computes the future value of that payment stream using the future value of an annuity formula, based on your payment frequency (which can differ from the compounding frequency) — then adds it to the lump-sum future value for the total.
Choosing "Beginning of Period" payment timing (an annuity due) versus "End of Period" (an ordinary annuity) shifts every contribution one period earlier, giving each one slightly more time to compound and therefore a slightly higher future value for the same total contributions.
See It In Action
Who Uses Future Value Calculator and Why
- Projecting how a lump-sum investment plus ongoing monthly contributions will grow over a specific number of years toward a retirement or savings goal.
- Comparing how the same monthly contribution grows differently depending on the assumed rate of return, using the calculator's rate comparison table.
- Estimating the future value of a child's college fund or a house down-payment fund from a current balance and a planned monthly deposit.
- Checking how much of a future account balance is actually compound interest earned versus money you personally deposited.
Mistakes to Avoid
- Assuming compounding frequency and contribution frequency are the same thing — they're independent settings in this calculator, and mixing them up (e.g., assuming monthly contributions automatically means monthly compounding) can produce a confusing result if you don't check both.
- Forgetting that 'Beginning of Period' contributions compound for slightly longer than 'End of Period' ones — over many years and many contributions, this small per-payment difference in annuity timing adds up to a real, if modest, gap in the final total.
- Assuming a single flat interest rate will hold steady for decades — the formula itself is exact, but real markets don't return the same rate every year, so long-horizon projections are best treated as an illustration of compounding, not a guaranteed number.
Tips for Best Results
- Use the built-in rate comparison table to see the same principal and contributions projected at several different rates side by side — it's a quick way to understand how sensitive a long-term projection is to the return assumption.
- Enter your actual planned contribution frequency (monthly, biweekly, etc.) separately from compounding frequency if your account compounds differently than you contribute — the calculator handles both independently rather than forcing them to match.
Fixing Common Problems
My total future value seems surprisingly high compared to what I actually deposited. — This is the expected effect of compounding over a long horizon — interest earned in early years keeps earning its own interest in later years, so over 15-20+ years it's common for compound interest earned to exceed total contributions, especially at higher assumed rates.
Switching contribution timing from end-of-period to beginning-of-period barely changed my result. — The effect is real but modest for most timeframes — it only shifts each contribution by one period earlier, so the gap becomes more noticeable with a higher interest rate or a very large number of contributions.
Terms Explained
Principal: The initial lump sum you start with, before any interest or contributions are added.
Compounding frequency: How often interest is calculated and added to the balance (e.g., monthly or annually) — distinct from how often you personally contribute money.