Calculators that show their working
Most personal-finance calculators hand you a confident number and hide the assumptions that produced it. Several of them are quietly rigged — comparing two options while charging only one of them its real costs. These are built the other way round: every assumption is an input you can see and change, every cost is counted on both sides, and the page tells you what it deliberately does not model.
Available now
Buy a flat, or rent and invest the difference?
Holds both choices to the identical monthly budget, counts stamp duty, home-loan tax relief, rental income tax and capital gains on both sides — then runs the whole thing across hundreds of return paths to show how often each answer actually wins.
Retirement · EPF · NPS · SIPRetirement is not the first bill that arrives
A house, a car, school fees, a post-graduation, a wedding — they all land before retirement does, out of the same pot. Enter each goal in today’s money and the year you need it; the tool inflates it at a rate that fits the category, funds it by rules you set when money is short, adds up EPF, NPS and your SIPs, and then spends the corpus down to the age you nominate to see whether it actually lasts.
What is coming next
SIP reality check Coming soon!
What a SIP actually returned over every rolling window, against what the smooth CAGR line promised.
Loan true-cost calculator Coming soon!
Processing fees, insurance bundling and prepayment penalties, converted into the interest rate you are really paying.
The rules
- Symmetry first. If a tool compares two choices, both are held to the same budget and the same treatment. No option gets income the other is denied, or escapes a cost the other pays.
- Assumptions are inputs, not secrets. Including the tax rates, which are dated and editable — because they change with every Budget and a hardcoded rate is a slow-acting bug.
- Costs are counted. Stamp duty, brokerage, expense ratios, exit taxes. The friction is usually where the answer actually lives.
- Uncertainty is shown, not hidden. A single expected return is a story. Where it matters, the tool runs the comparison many times and reports how often each side wins.
- Limits are stated. Each tool says plainly what it does not model — and none of them price liquidity, flexibility, or the value of a home you cannot be asked to leave.
Everything here is personal research published for thinking with, not investment advice. Verify the tax assumptions against the current year before relying on any output.