Rent vs buy
Compare total cash spent on a mortgage and home ownership against renting and investing your down payment over a chosen horizon.
Open calculatorMortgage
Loan principal equals property price minus your down payment. Equal (annuity) instalments keep the monthly payment constant; declining instalments repay a fixed slice of principal each month so the payment starts higher, falls over time, and reduces total interest paid.
Loan details
Property purchase price.
$
Down payment as a percentage of the property price.
%
Nominal annual interest rate (held constant across the term in this model).
%
Repayment term in years (1–50).
Equal instalments keep the monthly bill constant; declining instalments cost more at first but save total interest.
- Down payment
- 100,000.00 $
- Loan principal borrowed
- 400,000.00 $
Payments and total cost
First monthly payment
2,700.83 $
Total amount repaid
810,248.59 $
Total interest over term
410,248.59 $
Last monthly payment
2,700.83 $
Loan principal borrowed
400,000.00 $
Loan-to-value (LTV)
80.0%
The link may contain your inputs. Anyone receiving it can read them.
Sliders and preset values
Loan terms and extra costsReference rate, bank margin, insurance and first payment month.
%
%
Margin markup (e.g. +0.5%) applied until balance drops below 80% LTV.
%
%
Early repayment simulator
$
Cost structure & loan safety
Loan principal borrowed
400,000 $(49.4%)
Total interest over term
410,249 $(50.6%)
First installment breakdown: 2,700.83 $
Principal: 534.16 $ (20%)Interest: 2,166.67 $ (80%)
LtV ratio: 80.0%Safe (≤80%)
0%80%90%100%
Repayment timeline (principal vs interest)
Remaining principal balanceCumulative interest paid
How was this calculated?
- Principal: 500000 × (1 − 20 ÷ 100) = 400,000.00 $.
- Number of payments: 25 × 12, rounded to an integer = 300.
- Monthly rate r = 6.5 ÷ 100 ÷ 12. Annuity payment: 400,000.00 $ × r × (1+r)^300 ÷ ((1+r)^300 − 1) = 2,700.83 $.
- The model sums interest on the balance each month: 410,248.59 $; principal and interest together: 810,248.59 $.
Constant rate throughout, excluding fees and insurance. Monthly payments are not rounded in the calculation; displayed amounts are rounded to two decimal places.
Amortization schedule
Detailed breakdown of principal, interest, insurance and remaining balance over time.
Select year:
| No. | Date | Total payment | Principal | Interest | Remaining balance | LTV |
|---|---|---|---|---|---|---|
| 1 | 11.2026 | 2,700.83 $ | 534.16 $ | 2,166.67 $ | 399,465.84 $ | 79.9% |
| 2 | 12.2026 | 2,700.83 $ | 537.06 $ | 2,163.77 $ | 398,928.78 $ | 79.8% |
| 1. 2026 | 5,401.66 $ | 1,071.22 $ | 4,330.44 $ | 398,928.78 $ | 79.8% | |
Compare scenarios
Snapshot A stays only in this page’s memory. Refreshing or leaving the calculator removes it; it is not added to links or sent to the server. The percentage change uses the absolute value of A; it is not defined when A is zero.
Sensitivity analysis
These simulations change only the indicated parameter; all other assumptions match the form. They are not forecasts or confidence intervals. The initial variants are editable examples.
%
%
| Scenario | Annual interest rate % (%) | First monthly payment ($/month) | Difference from baseline ($/month) |
|---|---|---|---|
| Baseline | 6.5 | 2,700.83 | 0 |
| Variant 1 | 5.2 | 2,385.21 | -315.62 |
| Variant 2 | 7.8 | 3,034.46 | 333.63 |
Blank, invalid or unavailable results are shown as a dash.
Calculation report (A4 / PDF)
Live previewThis report contains your inputs. Printing and sharing are your choice; it was prepared locally.
Constant rate throughout, excluding fees and insurance. Monthly payments are not rounded in the calculation; displayed amounts are rounded to two decimal places.
User-provided parameters; the RiverMath model does not fetch an external rate.
100% local in browser
rivermath.com · Prepared locally
This document is for informational purposes only and does not constitute a commercial offer or energy audit.
Recent on this calculator
Full historyStored strictly in this browser’s local storage. Clicking an entry reloads the parameters into the calculator URL; sharing the link exposes those inputs to the recipient.
No saved calculations yet. Use any calculator and your recent results will appear here.
Frequently asked questions
What is the difference between equal (annuity) and declining instalments?
Equal (annuity) instalments keep your monthly payment constant (mostly interest in the early years, mostly principal later). Declining instalments repay an equal slice of principal every month, so initial payments are higher, decline steadily over time, and result in lower total interest paid.
How does the down payment affect the monthly instalment and LTV?
A larger down payment reduces the principal borrowed, your monthly instalment and the loan-to-value (LTV) ratio. Lower LTV ratios (typically ≤80%, i.e. 20%+ down) usually unlock lower bank interest margins.
Is the interest rate entered here the APR / RRSO?
No. Enter the nominal annual interest rate (base rate plus bank margin). APR/RRSO also folds in arrangement fees, valuation costs and mandatory insurance policies.
How is the loan amount calculated from the property price?
The down-payment percentage is subtracted from the purchase price. On a 500,000 property with a 20% down payment (100,000), the loan principal borrowed is 400,000.
Will my instalment change if interest rates rise?
Yes, on a variable-rate mortgage (or when a fixed-rate period resets). Always test a rate 1–2 percentage points higher to make sure your household budget can absorb rate hikes.
Educational estimate only. Not medical, tax, legal or financial advice.