Guide · Mortgages & Property
Rent vs Buy: The Financial Calculation That Actually Matters
The "renting is dead money" narrative ignores the cost of mortgage interest, maintenance, transaction costs, and the opportunity cost of the deposit. Here is the full comparison — and the numbers that actually drive the decision.
The true costs of buying
Buying a home is not just a mortgage vs rent comparison. The full cost of ownership includes several categories renters never pay:
| Cost | Buying | Renting |
|---|---|---|
| Upfront costs | £20,000+ (SDLT, legal, survey) | £0–£2,000 (deposit, fees) |
| Monthly housing payment | £1,343 (mortgage at 4.5%) | £1,100 (market rent) |
| Maintenance (annual) | ~£3,000 (1% of value) | £0 |
| Buildings insurance | ~£250/year | £0 (contents only) |
| Flexibility to move | Low (transaction cost ~5–8%) | High (1–2 months notice) |
Assumes 10% deposit (£30,000), 25-year mortgage at 4.5%, stamp duty ~£5,000. Market rent is illustrative. Maintenance varies widely by property age and type.
The price-to-rent ratio
A useful shorthand for the rent vs buy decision is the price-to-rent ratio: property price divided by annual rent. A ratio above 20 generally favours renting (buying is expensive relative to the rental market); below 15 generally favours buying.
| P/R Ratio | Interpretation |
|---|---|
| Under 15 | Buying likely favourable |
| 15–20 | Roughly neutral — depends on personal factors |
| Over 20 | Renting likely more cost-effective |
| Over 25 | Buying requires strong expected appreciation to break even |
London's price-to-rent ratio is typically 25–35+, which is why the rent-vs-buy calculation frequently favours renting there even over long periods. Northern cities with ratios of 12–16 often tip the other way.
The opportunity cost of the deposit
A £30,000 deposit sitting in a house earns no investment return on its own — instead, it buys equity in an asset that (hopefully) appreciates. If that £30,000 were invested in a global equity fund at 7% annual return instead, it would grow to ~£59,000 in 10 years. Meanwhile, a £300,000 house appreciating at 4% annually would be worth £444,000 — a £144,000 gain. The 10% stake represented by the deposit would have grown from £30,000 to £44,400.
In this scenario, the investment alternative wins (£59,000 vs £44,400 on the deposit equivalent) — before accounting for rent saved, mortgage interest paid, and maintenance. The full calculation requires modelling all cash flows over the comparison period, which our calculator does.
Non-financial factors that tip the decision
The financial analysis rarely gives a clear winner — the margin is often small and depends heavily on assumptions that cannot be known in advance. The non-financial factors frequently dominate:
- Security of tenure — Owning eliminates the risk of being evicted by a landlord.
- Freedom to modify — Owners can decorate, renovate, and make a home their own.
- Geographical flexibility — Renting makes it easier to move for work or lifestyle.
- Forced savings — Mortgage repayment is effectively compulsory wealth-building that renters must replicate through active discipline.
Frequently asked questions
Is renting really 'dead money'?
No — this is a persistent myth. Rent buys you shelter, flexibility, and freedom from the costs of ownership. Every mortgage payment also includes interest (which is 'dead money' in the same sense), plus maintenance, insurance, and transaction costs that renters avoid. Whether buying creates more wealth than renting depends on house price growth, rent levels, investment returns on the deposit alternative, and how long you stay.
What are the true costs of buying a home?
Beyond the mortgage: Stamp Duty (up to 12% of purchase price in England), solicitor fees (~£1,500–£3,000), survey costs (£300–£1,500), mortgage arrangement fees (£0–£2,000), buildings insurance, and ongoing maintenance (typically 1–2% of property value per year). These costs are never incurred by renters and significantly affect the break-even analysis.
How long do you need to stay for buying to beat renting?
The break-even period depends on the price-to-rent ratio, expected capital growth, and local market conditions. In high price-to-rent ratio markets (like London), it can take 10+ years for buying to outperform renting after accounting for transaction costs and opportunity cost of the deposit. In lower-ratio markets, 3–5 years is more typical.
What is the opportunity cost of a deposit?
Every pound in a house deposit is a pound not invested elsewhere. A £50,000 deposit invested in a global equity index fund returning 7% annually grows to roughly £98,000 in 10 years. If house prices grow at 4% over the same period, the opportunity cost of the deposit needs to be offset by price appreciation and avoided rent — which is the heart of the rent vs buy calculation.