Set up a fair housing-cost race

A fair comparison invests the renter’s unused capital and cash-flow difference

Comparing rent only with a mortgage repayment is incomplete. A buyer uses a deposit and pays transaction costs; a renter can retain and invest that capital. A buyer also pays rates, insurance, repairs and possibly strata costs, while a renter pays rent and may face moving and contents-insurance costs.

This calculator starts the renter with the buyer’s deposit plus buying costs. Each month it compares the owner’s mortgage and entered ownership costs with the renter’s current rent and entered renter costs. When ownership costs more, the difference is added to the renter’s investment. When renting costs more, the difference is withdrawn. Both households therefore use the same modelled housing budget.

How the buying lane builds equity

The starting loan is purchase price minus deposit. The page calculates a monthly principal-and-interest repayment for the entered rate and term, then amortises the balance month by month over the comparison horizon. Interest paid is accumulated separately so principal repayment is not mislabelled as a cost.

The home value compounds at the entered annual growth rate. At the finish line, selling costs are deducted from projected value and the remaining mortgage is repaid. What remains is sale-adjusted home equity. This puts the owner result on a realisable basis rather than comparing a gross property value with a liquid investment account.

Buying costs are treated as cash consumed at the start, not home equity. Enter transfer duty from the relevant state or territory calculator, conveyancing, inspection, registration and known lender costs. Lenders mortgage insurance, grants and concessions must be entered in the net amount if relevant.

How the renting lane accumulates investments

The renter’s initial investment equals the deposit and buying costs not committed to a property. It grows monthly using the entered investment return less the entered annual fee or tax drag. Monthly housing savings are contributed after that month’s growth; monthly shortfalls reduce the account.

Investment returns are uncertain and rarely smooth. Tax can depend on interest, distributions, franking, realised gains and account ownership. The single drag field is only an economic allowance. Run lower-return and higher-fee cases instead of presenting one forecast as likely.

Rent increases monthly at the annual growth assumption in this model. Real rent reviews occur at discrete lease dates and are constrained by market and state law, so the projection is a smoothed planning path. Moving frequency, bonds, utility connection and rental gaps can be included in the annual renter allowance.

Ownership costs need more than rates and insurance

Maintenance is lumpy. A roof, hot-water system or special strata levy may arrive in one year even though the model spreads an annual allowance evenly. Review building reports, strata records and insurance exposure before choosing the input.

Owner-occupier capital gains may receive a main-residence exemption when conditions are satisfied, but not every period, use or property qualifies. The calculator excludes tax on both the home and renter investments. Add advice for mixed use, absence, foreign-residency or investment-property facts.

Interest-rate stress tests cash flow, not just final wealth

Moneysmart suggests allowing breathing room and checking affordability if rates rise. The stress output recalculates the payment on the original loan and term at the entered rate plus the stress increment. It does not rerun the full wealth race at that rate.

Actual variable rates can change repeatedly. Fixed rates expire, repayments can reset, offsets reduce interest and redraw can increase the effective balance. Enter the expected average loan rate for a long-term comparison, then test near-term cash flow separately with lender-specific fees and features.

A buyer can appear wealthier at the finish line yet face unaffordable monthly payments during the path. Keep an emergency reserve outside the deposit, account for income interruption and do not treat property equity as immediately spendable.

Worked example: an $800,000 home and a comparable $650 weekly rental

Start with a $160,000 deposit, $35,000 of buying costs and a $640,000 loan at 6% over 30 years. Enter $15,000 a year for rates, insurance, maintenance and strata. The buyer’s first-month housing outflow is the calculated principal-and-interest payment plus one-twelfth of those ownership costs.

The renter begins with $195,000 because the deposit and buying costs remain available. Weekly rent of $650 converts to an average monthly amount using 52 weeks divided by 12, then the renter allowance is added. When the owner outflow is higher, the monthly difference goes into the renter portfolio. That portfolio compounds at the entered investment return after the fee or tax drag.

After ten years, the buyer’s projected home value is reduced by selling costs and the remaining mortgage. The renter keeps the investment account. The result is not “money spent”: it is a comparison of modelled net assets after equalising monthly housing budgets. Mortgage principal builds owner equity, while renter contributions build financial assets.

Change home growth from 3% to 1%, investment return from 5% to 3%, or selling costs from 2.5% to 4% one at a time. The ranking may reverse. That sensitivity is more useful than quoting the central difference to the nearest dollar.

Four break-even questions reveal which assumption drives the decision

First, ask what home growth rate makes sale-adjusted owner equity match renter wealth. The calculator does not solve that rate automatically, but changing the growth input in small steps exposes the threshold. Compare it with a cautious range rather than a remembered national average.

Second, ask how long the household is likely to stay. Short horizons give buying and selling costs little time to be spread across years. Long horizons magnify uncertain compound growth and investment returns. A plan to move for work or family should be reflected explicitly.

Third, test the cash-flow boundary. Raise the mortgage rate by two or three percentage points and add a realistic repair. If the required buffer is unavailable, a favourable long-run equity estimate does not resolve short-run default or forced-sale risk.

Fourth, test renter discipline. Reduce the investment return or monthly contribution if the deposit and savings would remain in cash or be spent. The financial advantage of renting in many scenarios depends on preserving and investing the unused capital. Record the scenario that matches actual behaviour, not an idealised strategy.

Housing utility and flexibility belong beside the numbers

Buying can provide control, tenure security and freedom to modify, but it concentrates capital and makes relocation expensive. Renting can provide flexibility and access to a location that is costly to purchase, but leases can end and moving can disrupt work, school and community ties.

The compared properties must be genuinely similar. A small rental near work and a large purchased home on a long commute do not deliver the same housing service. Include transport, time, school and space consequences outside the calculator.

Choose a horizon that reflects likely tenure. Transaction costs matter most over short periods, while growth assumptions dominate long periods. Re-run at several horizons and with home growth or investment return lower by two percentage points. If the preferred decision changes easily, flexibility and risk tolerance deserve more weight than the central estimate.