Build a rent vs buy calculator that compares costs over time, with editable assumptions
Whether renting or buying works out better depends on how long you stay, what happens to house prices and rents, interest rates, and what your deposit would have earned elsewhere. A rent vs buy calculator can't know those things, but it can lay them side by side and show which assumptions swing the answer. Anticode can build one with every assumption editable, a year-by-year comparison and a break-even point.
What a fair comparison includes
Simple comparisons set the monthly rent against the monthly mortgage payment and stop. That misses most of what matters, in both directions. A fair model counts the following:
| Buying | Renting | |
|---|---|---|
| Up front | Deposit, purchase taxes and fees, legal and survey costs, moving | Deposit held by the landlord, moving, any letting fees where allowed |
| Every month | Mortgage interest, the capital part of the payment, insurance, service charges or ground rent | Rent, contents insurance |
| Every year | Maintenance and repairs, often estimated as a percentage of the home's value; property taxes | Rent increases |
| Opportunity cost | The deposit and fees can't earn returns elsewhere | The money not spent on a deposit can be invested |
| At the end | Home value minus mortgage left and selling costs | The invested savings, minus any tax on gains |
The opportunity-cost row is the one most calculators leave out, and it's often what decides the result over shorter periods. Equally, ignoring maintenance makes buying look cheaper than it is.
Assumptions to put on screen
- House price growth per year
- Rent increase per year
- Mortgage rate, term and whether the rate is fixed for a period
- Return on invested savings, after fees
- Inflation, if results are shown in today's money
- Maintenance as a percentage of value
- Buying and selling costs as percentages or amounts
- How many years the person expects to stay
Give each a sensible default with a note on where it came from, and let the user change it. A small sensitivity panel helps: show how the break-even year moves if house prices rise one percentage point slower or faster. The answer often flips within a plausible range, and seeing that is the most honest output the tool can give.
Describe it to Anticode
"A rent vs buy calculator for first-time buyers. Inputs: home price, deposit, buying costs, mortgage rate and term, monthly rent for a comparable home, years expected to stay. Assumptions panel, all editable with defaults and notes: house price growth, rent increase, investment return after fees, maintenance as a percentage of value, selling costs, insurance and service charges. Output: a year-by-year table and a chart of the net position of each option, the break-even year, and a sensitivity view for house price growth and investment return. Results in today's money with a switch. A visible line saying it's a simplified model, not financial advice, and excludes tax rules. Remember inputs in this browser and export the table as CSV."
Test it with a case you can check by hand, such as zero growth and zero returns everywhere: then buying costs roughly the buying and selling costs plus interest and maintenance, and renting costs the rent paid. If the numbers don't match your spreadsheet, ask for a fix in plain words.
Affordability is a different question
"Should I rent or buy?" and "Can I afford to buy?" get mixed up. Affordability depends on what lenders will offer, which depends on their own rules and the person's circumstances. Keep it separate: a simple affordability check can show the monthly payment at a given price and rate, and what share of take-home pay it is, without pretending to know what a lender will approve. For the payment maths itself, see the mortgage calculator app.
Limits
- No live rates or prices. The app has no network, so it can't fetch mortgage rates, local rents or house price data; users type their own.
- No tax rules unless you write and maintain them; purchase taxes and tax on gains vary between countries and change often.
- Not advice. It doesn't account for job security, family plans or the value of stability, which often matter more than the numbers.
- Saved locally. Inputs stay in the user's browser and nothing reaches you.
Estate agents and mortgage brokers using it as a lead tool can add an optional contact form for people who want to talk; see the mortgage brokers page. For long-run saving, the compound interest calculator pairs well.
Questions people ask
Which is cheaper, renting or buying?
It depends on how long you stay, prices, rates and returns. A rent vs buy calculator shows which of those swing the answer for you.
Why does my deposit count as a cost?
Because money in a home can't earn returns elsewhere. Including that is what makes the comparison fair.
Does it use current mortgage rates?
No. It can't fetch live data, so enter a rate from a lender or broker.