Home loan calculator

Mortgage repayments

Work out your repayments and total interest — and see how much sooner you'd be debt-free by paying a little extra each month.

Mortgage repayment calculator

Your repayments, the total interest, and how much faster extra repayments clear the loan.

Loan amount

Interest rate (%)

Loan term (years)

Extra repayment / month

Your repayment

$3,597/mo

Total interest

$695,029

Total to repay

$1,295,029

Paid off in

30.0 yrs

If interest rates rise (your minimum repayment)

Rate 7.00% (+1%)$3,992/mo+$395

Rate 8.00% (+2%)$4,403/mo+$805

Rate 9.00% (+3%)$4,828/mo+$1,230

APRA requires lenders to test new borrowers against a 3% rate rise. This is the minimum repayment if your rate climbs.

Loan balance over time

Principal & interest, repaid monthly at a constant rate. Real rates change over time and this excludes fees, offset accounts and redraw. A guide, not financial advice.

Over 30.0 years you repay

$1,295,029

$695,029 of that is interest — that's 116% on top of the $600,000 you borrowed.

Interest paid

$695,029

Interest / loan

116%

Repayments

360

Principal beats interest

Year 19

Year-by-year amortisation

Year	Interest	Principal	Balance	Paid off
1	$35,800	$7,368	$592,632	1%
2	$35,345	$7,823	$584,809	3%
3	$34,863	$8,305	$576,504	4%
4	$34,350	$8,817	$567,687	5%
5	$33,807	$9,361	$558,326	7%
6	$33,229	$9,938	$548,388	9%
7	$32,616	$10,551	$537,836	10%
8	$31,965	$11,202	$526,634	12%
9	$31,275	$11,893	$514,741	14%
10	$30,541	$12,627	$502,114	16%
11	$29,762	$13,405	$488,709	19%
12	$28,935	$14,232	$474,477	21%
13	$28,058	$15,110	$459,367	23%
14	$27,126	$16,042	$443,325	26%
15	$26,136	$17,031	$426,293	29%
16	$25,086	$18,082	$408,211	32%
17	$23,970	$19,197	$389,014	35%
18	$22,786	$20,381	$368,633	39%
19	$21,529	$21,638	$346,994	42%
20	$20,195	$22,973	$324,022	46%
21	$18,778	$24,390	$299,632	50%
22	$17,274	$25,894	$273,738	54%
23	$15,676	$27,491	$246,246	59%
24	$13,981	$29,187	$217,060	64%
25	$12,181	$30,987	$186,073	69%
26	$10,269	$32,898	$153,174	74%
27	$8,240	$34,927	$118,247	80%
28	$6,086	$37,082	$81,165	86%
29	$3,799	$39,369	$41,797	93%
30	$1,371	$41,797	$0	100%
Total	$695,029	$600,000	$0	100%

Early on almost every dollar goes to interest; the balance falls slowly then accelerates. You start paying off more principal than interest from year 19.

What each extra repayment buys you

Extra / mo	New repayment	Interest saved	Debt-free in
+$100	$3,697/mo	$58,423	27.9 yrs(−2.1)
+$250	$3,847/mo	$127,872	25.3 yrs(−4.7)
+$500	$4,097/mo	$212,713	22.1 yrs(−7.9)
+$1,000	$4,597/mo	$320,590	17.7 yrs(−12.3)

Every extra dollar comes off the principal, so it never gets charged interest again — which is why small top-ups clear years off the loan.

Lifetime cost if your rate is different

Rate	Repayment	Total interest	Total repaid
5.00%	$3,221/mo	$559,535	$1,159,535
5.50%	$3,407/mo	$626,424	$1,226,424
6.00%today	$3,597/mo	$695,029	$1,295,029
7.00%	$3,992/mo	$837,053	$1,437,053
8.00%	$4,403/mo	$984,931	$1,584,931
9.00%	$4,828/mo	$1,137,985	$1,737,985

Same loan and term, minimum repayments only. A rate that's a point higher can add tens of thousands over the life of the loan.

Second layer · offset, timing & the balance path

Offset account — savings that beat down interest

Offset balance

Added to offset / mo

$20,000 in your offset plus $500/mo saves

$265,575

in interest and clears the loan 6.1 years sooner — and every dollar of that offset is still yours to withdraw.

Interest saved

$265,575

Time saved

6.1 yrs

Offset at payoff

$163,500

Interest dodged, yr 1

$1,200

Interest is charged on your balance minus the offset, so parking $20,000 there is like earning 6.00% tax-free on it — worth about $1,200 in the first year, while staying fully liquid. Your repayment doesn't change; the loan just clears faster.

Same money, different timing

Amount to deploy

Spread rate

$56/mo over 30 yrs

Strategy	Deployed	Interest saved	Debt-free in
Lump sum todaywinner	$20,000	$91,647	27.4 yrs(−2.6)
Dripped $56/mo	$19,222	$33,910	28.8 yrs(−1.2)

Roughly the same $20,000 either way, but paying it today saves an extra $57,737 — because a dollar taken off the balance now avoids years of compounding, while a dollar dripped later only avoids what's left.

Balance path — with vs without extra

Minimum repaymentsWith offsetLump sum today

Each line is the loan balance year by year. The steeper the fall, the faster you're debt-free — an offset or an early lump bends the curve down sooner and shrinks the area under it, which is the interest you pay.

Principal & interest repaid monthly at a constant rate, built from your loan, rate and term above. Offset and lump-sum figures assume the rate holds and the repayment stays fixed; they exclude fees, redraw rules and any interest earned elsewhere. A guide, not financial advice.

A lender tells you the minimum you must pay. What it rarely shows is the total interest behind that number, or how sharply that total falls when you pay more than you have to. On a long loan the interest can rival the amount borrowed, and the two levers that move it — your rate, and anything above the minimum — sit side by side here.

It also answers what a rate rise does to the budget. Every figure comes from a month-by-month simulation rather than a rule of thumb, so the payoff date and the interest saved are the real output of the schedule you describe.

How this is calculated

1
The minimum repayment
Your loan, the annual rate divided by twelve and the term in months go into the standard principal-and-interest formula. It returns the level monthly repayment that clears the balance to exactly zero in the final month.
2
The loan is run month by month
Each month's interest is the balance times one twelfth of the annual rate. The repayment covers that first; what is left cuts the principal. Total interest is the sum of every charge, and the payoff date is the month the balance hits zero.
3
The extra-repayment scenario
The same simulation runs again at the minimum plus your extra, loan and rate unchanged. More principal is retired from month one, so the balance falls faster. Interest saved and years saved are the gap between the two runs.
4
The rate-rise stress test
The minimum is recalculated at your rate plus one, two and three percentage points, holding the loan and term fixed. That is what your required repayment becomes — not what you would pay by choosing to keep repaying today's amount.
5
The deeper breakdown
The advanced section rebuilds the schedule year by year and flags the first year principal beats interest. It also models an offset, where interest is charged on the balance minus the offset, and pits a lump sum today against the same dollars dripped monthly.

What it assumes

The rate is held constant for the life of the loan. Fixed periods ending, cuts, hikes and refinancing are not modelled — a variable rate moves many times over thirty years.
Principal and interest, monthly, from the first month. Interest-only periods, repayment pauses and fortnightly schedules are not modelled.
No fees: application and settlement costs, ongoing account or package fees, valuation and discharge fees, break costs and lenders mortgage insurance are all excluded.
Extra repayments are assumed to be allowed and uncapped. Many fixed-rate loans limit what you can pay ahead each year, and redraw conditions differ by lender.
The offset and lump-sum models assume the money stays put and earns nothing elsewhere. Nothing here is tax-aware either: a loan against an investment property is treated very differently from one on the home you live in.

Common questions

Why does a small extra repayment cut years off the loan?

Early on almost all of your repayment is interest and barely any principal is retired. An extra dollar skips that queue and is never charged interest again for the decades left to run. That avoided interest is what buys the years back.

Extra repayments, or money in an offset account?

While the money stays put the arithmetic is nearly identical: both shrink the balance interest is charged on. The difference is access — offset money stays your own savings, while redraw on extra repayments sits at the lender's discretion.

Is a shorter term better than paying extra?

They finish at the same point if the dollars going in are the same. The difference is commitment: a shorter term makes the higher repayment contractual, while extra repayments leave you the option to drop back — and the risk you quietly stop.

Why does the stress test go to three percentage points?

That is the buffer APRA expects lenders to apply when assessing a new borrower: they check you could still meet repayments at around three percentage points above the rate on offer. Running it on your own loan tests whether the budget survives a full cycle.

Does paying fortnightly clear a loan faster?

Only if you pay half the monthly repayment every fortnight: twenty-six fortnights is thirteen months' worth in a year, so the thirteenth is an extra repayment in disguise. This tool works in whole months — approximate it by entering one twelfth of your repayment as the extra.

Sources: APRA — Prudential Practice Guide APG 223 (residential mortgage lending) · RBA — Interest rate statistics · ASIC MoneySmart — Home loans · All data sources

General information only, not financial advice. Figures are estimates based on the inputs and assumptions above and don't account for your personal circumstances. Confirm anything important with the relevant authority or a licensed adviser.

How this is calculated

The minimum repayment

The loan is run month by month

The extra-repayment scenario

The rate-rise stress test

The deeper breakdown