How to Calculate Rent vs Buy (2025 Complete Guide)

The mistake most people make

Most rent vs buy comparisons simply compare the monthly mortgage payment to the monthly rent. This is wrong, and it almost always makes buying look cheaper than it really is.

A proper analysis must include all costs of ownership, the opportunity cost of the down payment, and the time value of money. This guide walks you through each component.

Step 1: Calculate the true cost of buying

The true monthly cost of ownership includes:

• Mortgage payment — principal and interest, calculated using the amortization formula
• Property taxes — 0.5–1.5% of home value per year depending on country and location
• Home insurance — typically 0.3–0.5% of home value per year
• Maintenance and repairs — budget 1–2% of home value per year (many homeowners underestimate this)
• HOA/service charges — relevant for flats and managed developments

Add these together and you have the true monthly cost of ownership — typically 30–50% higher than the mortgage payment alone.

Step 2: Calculate the opportunity cost of the down payment

This is the most important factor that most calculators ignore. When you put down a 10% deposit on a £400,000 home (£40,000), that money is no longer available to invest. If global stock markets return 7% annually, the opportunity cost of that £40,000 is significant:

• After 5 years: £40,000 would have grown to £56,100 (a £16,100 opportunity cost)
• After 10 years: £40,000 would have grown to £78,700 (a £38,700 opportunity cost)
• After 20 years: £40,000 would have grown to £154,800 (a £114,800 opportunity cost)

The renter's scenario should assume this capital is invested, not spent. This often makes renting look significantly more competitive than naive comparisons suggest.

Step 3: Calculate the break-even point

The break-even point is the year at which buying becomes financially superior to renting. Before that year, the renter who invested the down payment is ahead. After that year, the homeowner is ahead due to equity build-up and appreciation.

The formula for a rough break-even estimate:

In practice, use a calculator — the actual calculation requires modelling each year's equity, tax position, and rent increases.

Country-specific factors

🇬🇧 United Kingdom

Stamp Duty Land Tax (SDLT) adds 0–12% to purchase costs depending on price. The nil-rate threshold is currently £250,000. First-time buyers get relief up to £425,000. Ongoing costs include council tax (separately from property tax) and typically a leasehold service charge for flats. Mortgage rates in 2024–2025 range from 4–5.5% for 2-year fixes.

🇺🇸 United States

Property taxes vary wildly by state — from 0.3% in Hawaii to over 2% in New Jersey and Illinois. Closing costs run 2–5% of purchase price. The mortgage interest deduction can reduce the effective cost of a mortgage for itemising taxpayers. Real estate agent fees on sale are typically 5–6% of sale price.

🇨🇦 Canada

Land transfer taxes vary by province. Ontario and BC have the highest rates. The federal First Home Savings Account (FHSA) allows tax-deductible contributions up to $40,000 toward a first home purchase. CMHC mortgage insurance is mandatory for down payments under 20%.

🇦🇺 Australia

Stamp duty is a state tax and rates vary significantly. NSW and Victoria have the highest rates. The First Home Owner Grant (FHOG) provides a cash payment to eligible first-time buyers. Negative gearing rules mean investment property owners can offset property losses against income.

When buying almost always makes sense

• You plan to stay for 7+ years in the same property
• Local rent-to-price ratios are low (annual rent > 5% of purchase price)
• You have a substantial deposit (20%+) reducing mortgage interest costs
• Mortgage rates are historically low relative to historical averages

When renting is often the better choice

• You plan to move within 3–5 years — transaction costs alone can exceed 7–10% of home value
• You're in a high price-to-rent ratio market (London, Sydney, Vancouver)
• You have a small deposit (5–10%) and face high mortgage insurance costs
• You would invest the down payment difference at a high expected return