True Cost of Homeownership Calculator

Homeownership costs far more than the mortgage payment. Maintenance is often budgeted at around 1-2% of property value per year, insurance is typically a fraction of a percent, and property tax varies hugely by jurisdiction. A 300,000 home with 1,300 monthly mortgage plus 3,000 annual maintenance plus 600 insurance plus 2,000 tax = 21,200/year total — 36% over the mortgage alone. Over 25 years that is 530,000 — dwarfing the original purchase price.

A worked example

With the defaults: monthly mortgage payment of 1,300, annual maintenance of 3,000, annual insurance of 600, annual property tax of 2,000. The tool returns 21,200.00. You can adjust any input and the result updates as you type — no submit button, no reload. That's the real power here: seeing how sensitive the output is to one or two assumptions.

What moves the number most

The result responds to Monthly Mortgage Payment, Annual Maintenance, Annual Insurance, and Annual Property Tax.

The formula behind this

Annual sum of mortgage payment × 12 plus other costs. Projects to 10 and 25 years. Ignores cost growth and mortgage payoff — both real factors over long horizons. Everything the calculator does is shown in the formula box below, so you can check the math against your own spreadsheet if you want.

Stress-testing the assumptions

Try the calculator at today's numbers, then adjust each input upward by 10-20% and watch which one moves the total most. A small change to the Monthly Mortgage Payment shifts the 25-year total far more than a small change to insurance — the four inputs don't carry equal weight. If you're modelling a rate reset at renewal, raise the Monthly Mortgage Payment input by the expected payment delta rather than entering a rate; this tool sums fixed payments, not interest rates.

What this doesn't capture

The figure excludes inflation on maintenance, insurance, and property tax (all three usually drift upward over a 25-year horizon — the projection assumes today's figures hold). It also excludes the principal portion of the mortgage that builds equity rather than disappearing as cost, property appreciation or depreciation, opportunity cost of the deposit (capital that could have been invested elsewhere), one-off costs like surveys or renovation work, and any tax relief or allowances that may apply locally.