No black boxes. Every SumWize calculator uses a standard, published financial formula, and here we show you exactly which one, what we assume, and a worked example you can check by hand.
Every calculation runs in your browser. Your numbers are never sent to a server or stored anywhere.
We use the same time-value-of-money math taught in finance courses and used by lenders, nothing proprietary or hidden.
Each tool states what it assumes and what it leaves out, so you know exactly what the number does and doesn't include.
Every worked example below can be verified with a basic calculator. If our math is off, we want to hear it.
Most of our tools are built from three classic formulas. Everything else is these, applied to a specific question.
The fixed monthly payment that pays off a loan over n months at monthly rate r:
What a starting balance plus a regular monthly deposit grows to:
The true yearly return once compounding is counted, for a stated rate compounded m times a year:
Open any calculator and the numbers update as you type, with the reasoning a click away.