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Money Tradeoff
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About Money Tradeoff

Every money decision is a choice not to do something else with the same money. These calculators work out what each choice has to achieve to come out ahead.

Why a break-even point instead of a forecast

Most calculators ask you to guess the future, such as how fast a home will grow or what your investments will earn, and then show a verdict built on that guess. The guess does all the work and the answer looks like a fact.

These turn the question around. Given everything that is knowable today, such as the price, the loan rate, the rent and the running costs, they find the one number that tips the decision. You still cannot know the future, but you can judge whether it is likely to beat a specific figure.

The calculators

How the figures are worked out

  • Each calculator compares two choices with the same money over the same period, and counts what the money would have earned had it gone the other way. That opportunity cost is the part a simple comparison of prices leaves out.
  • Loans are repaid with standard amortisation at a fixed rate. Investments grow at the return you enter, compounded once a year.
  • Every breakdown adds up to the total it explains, and the results are checked by automated tests, including every edge case the calculators were specified against.
  • The break-even figures are found by searching for the value at which the two choices finish exactly level, then checked by putting that value back in.

Each calculator's own page explains its assumptions in detail, and how we calculate covers testing, independence and corrections.

What they leave out

Tax, and the fees of buying and selling: no income or capital gains tax, no stamp duty, agent, legal, registration or dealer fees, and no insurance. These rules differ by country and often by state, so building in one country's would make the results wrong everywhere else. All figures are nominal, not adjusted for inflation.

Risk is also absent, because it is not a number. A savings account pays roughly what it promises; a home or a car can lose value faster than expected, and borrowing magnifies the outcome both ways. Two choices that break even on paper are not the same bet.

This is not advice

It is arithmetic with assumptions you control. It does not know your income, your tax position or your other commitments. Use it to frame the question, then take the question to someone qualified to answer it for your circumstances.