About this tool
Present & Future Value (TVM) Solver is a free, in-browser time-value-of-money calculator that solves any one of the five standard variables — present value, periodic payment, future value, interest rate or time — from the other four. Pick the unknown from the selector and its field is greyed out; everything else recomputes live as you type.
It uses the standard annuity accumulation equation FV = PV·(1+i)^n + PMT·((1+i)^n − 1)/i with end-of-period payments, where i is the periodic rate (annual rate ÷ payments per year) and n the number of periods. Rate is found by bracketed bisection and time by the logarithmic inversion, with zero-rate cases handled by the linear fallback.
Use it to answer questions like "what monthly deposit reaches 20,000 in 10 years at 6%?" or "what return do I need to double my money?". All math runs locally in your browser — nothing is uploaded.
Frequently asked questions
What conventions does the solver use?
The rate you enter is a nominal annual rate compounded at the payment frequency (annual% ÷ periods per year), payments are made at the end of each period, and time is entered and reported in years.
How is the interest rate solved?
There is no closed form, so the solver scans per-period rates from −99% to +200% for a sign change in the accumulation equation and then bisects with a capped iteration count; if no bracket exists it reports that no rate solves your inputs.
Why can the solved payment or present value be negative?
A negative result means the goal is already exceeded — for example the starting balance alone grows past the target future value, so no contribution (or even a withdrawal) would be needed.
Is my financial data uploaded anywhere?
No. The tool is a static page and every calculation runs locally in your browser; nothing you type ever leaves your device.
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