Finance Calculator
A five-variable TVM solver like the ones on financial calculators. Fill in four fields and leave exactly one blank — the solver computes it, including numerically solving for the interest rate.
How the Finance Calculator works
The calculation follows the standard method used across the US — no shortcuts, no hidden assumptions. Here is exactly what happens behind the scenes:
Formula
PV(1+i)ⁿ + PMT·[((1+i)ⁿ−1)/i] + FV = 0
- Enter cash outflows as positive and inflows as negative.
- Leave exactly one field empty — that is the unknown.
- The rate is solved by numerical root-finding when needed.
Frequently Asked Questions
What sign convention does this use?
Money you invest or pay is positive; money received is negative. For example, a loan has PV positive (you receive funds... actually you enter what you owe as negative) — treat payments you make as negative.
Why might no rate solve my inputs?
Some combinations have no real solution (e.g., payments too small relative to balance). The solver reports 'no solution' rather than returning nonsense.
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