How this finance calculator works
Pick the tab for the variable you want to solve (FV, PMT, I/Y, N, or PV), enter the other four, then Calculate. The tool uses standard time-value-of-money relationships with a periodic interest rate from your annual I/Y and periods per year (for example 12 when N counts months). Payments can be at the end or beginning of each period. Results include the solved value, total interest over the displayed schedule, sum of payments, a multi-series chart, and a period-by-period table.
The time value of money
Money today can earn a return or fund spending; the same nominal amount later has a different economic value. That is why lenders charge interest and investors expect compensation for waiting. Every loan payment, savings plan, and valuation builds on this idea.
Present value (PV)
Present value answers how much a future amount is worth today at a given discount rate. Higher rates and longer horizons reduce PV. Applications include comparing lump sums vs annuities, bond pricing intuition, and lease-vs-buy comparisons when you discount future cash flows.
Future value (FV)
Future value compounds a present amount — and any repeated payments — forward at the stated rate per period. It is useful for savings targets, growth scenarios, and checking whether a stated return and contribution plan reach a goal.
Periodic payment (PMT)
PMT is the level cash flow each period. Signs follow cash direction: money you pay is often entered negative; money you receive, positive. End-of-period timing matches most loans; beginning-of-period matches many leases and some insurance premiums.
Solving for I/Y and N
Rate and number of periods rarely have closed forms when both PV and PMT matter, so financial calculators use numerical methods. This page uses a robust bracket search for I/Y and a log-based formula for N when the standard rearrangement applies (and a linear case when the periodic rate is effectively zero).
Using it like a BA II Plus / HP 12C
- Enter I/Y as a percent per year (6 for 6%, not 0.06).
- Keep N and the payment frequency consistent (monthly N with periods/year = 12).
- Clear inputs between unrelated problems; mixed signs on PV/PMT/FV are normal.
For richer investment visuals and contribution timing options, see the investment calculator; for amortizing debt with principal/interest breakdown, the amortization calculator.