Useful arithmetic · No account
Free money tools
Four small utilities for the moments when understanding the principle is not enough and you need an actual number.
Tools that explain themselves
There is no account to create, no financial product waiting at the end and no “premium” button. The calculators do arithmetic; they do not decide what you should do.
Each tool sits next to an explanation of the assumptions, a worked example and the important ways reality can differ. That matters because a precise-looking result can still be wrong when the input or assumption is wrong.
Your numbers stay close
The safe-to-spend, growth and tax tools save their inputs in your browser so they are still there when you return. The invoice generator keeps the document in the current browser session and makes the PDF locally. None of the four sends financial inputs to a My Money Matters backend.
Choose the job in front of you
Safe-to-spend calculator
Put upcoming income and expenses on a timeline. See the lowest balance you reach, not only what is left at month-end.
Plan the next few weeks →Invoice generator
Make a clean PDF invoice with line items, banking details and optional VAT. No account, upload or watermark.
Make an invoice →Investment growth calculator
Explore a starting amount, monthly contributions, an assumed return, time and inflation. Open the workings month by month.
Explore compound growth →Income tax calculator
Estimate South African PAYE, rebates, medical credits, UIF and take-home pay using the SARS 2027 tax-year figures.
Estimate take-home pay →