Finance Calculator
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How This Calculator Solves the Time-Value-of-Money Equation
This calculator is built on the standard time-value-of-money (TVM) formula that links five variables: present value (PV), future value (FV), periodic payment (PMT), interest rate per period, and number of periods (N). Pick which value you want to solve for and the calculator rearranges the same underlying equation to isolate it. When solving for future value, it assumes any starting amount and any recurring payments both grow at the same compounding rate — the common convention used by virtually every general-purpose finance calculator. Interest is compounded once per payment period, which is the standard simplifying assumption when the compounding frequency and payment frequency match.
Beginning-of-Period vs. End-of-Period Payments
If you contribute at the start of each period (an "annuity due"), that money earns one extra period of interest compared to contributing at the end (an "ordinary annuity"). The difference is usually small for low rates but compounds meaningfully over long horizons or high contribution amounts — toggle the payment timing setting to see the effect on your result.
When to Use a More Specific Calculator
This tool is intentionally general-purpose. If you're modeling a fixed lump-sum investment with no ongoing contributions, the compound interest calculator may be more direct. If your goal is a specific retirement or savings target with regular contributions, the savings calculator and investment calculator add features like tax treatment and inflation adjustment that this general TVM model doesn't cover.
Frequently Asked Questions
Which value should I choose to "solve for"?
Solve for Future Value if you know how much you're starting with and contributing and want to know your end result. Solve for Present Value if you have a target amount and want to know how much to start with today. Solve for Payment if you know your goal and want to know how much to contribute each period. Solve for Number of Periods if you want to know how long it will take to reach a goal at a fixed contribution.
Why does changing payment timing from "end" to "beginning" of period change my result?
Payments made at the beginning of each period sit in the account for one extra compounding period compared to payments made at the end, so they earn slightly more interest over time. This is the standard distinction between an ordinary annuity (end-of-period) and an annuity due (beginning-of-period), and the effect grows with higher interest rates and longer time horizons.