The Help to Buy Shared Equity Calculator shows how an Australian shared-equity purchase splits a property price between your deposit, the government equity contribution, and your mortgage, then compares the monthly repayment against a standard 95 percent loan. Enter the property price, your deposit percentage, whether the home is a new build, the mortgage rate, and the term to see all three amounts and the repayment difference.
How It Works
- Validation: The calculator checks that the property price is above zero, the deposit and rate are not negative, the term is at least one year, and that deposit plus equity share does not exceed 100 percent of the price.
- Equity share: If you do not enter a custom equity percentage, the government share is set by the property type: 40 percent for a new build and 30 percent for an existing home, matching the Australian Help to Buy design built into this tool.
- Split and mortgage: The deposit and equity amounts are calculated from the price, and the mortgage is whatever remains after both are subtracted.
- Comparison: The same rate and term are applied to a standard loan of 95 percent of the price, and the difference between the two repayments is reported as your monthly saving.
Formula
The monthly repayment uses standard amortization. For a non-zero monthly rate:
where P is the mortgage amount, r is the annual interest rate divided by 12, and n is the term in years multiplied by 12. At zero interest, the payment is the mortgage divided by the number of months.
Input Parameters
| Parameter | Unit | Typical range | Notes | |---|---|---|---| | Property price | AUD | 300,000 to 1,200,000 | Full purchase price of the home | | Deposit percentage | Percent of price | 2 to 20 | Defaults to 2 percent in this calculator | | New build toggle | Yes or no | - | New build applies a 40 percent equity share, existing home 30 percent | | Equity loan percentage | Percent of price | 0 to 40 | Optional override of the default share | | Mortgage interest rate | Percent per year | 4 to 8 | Defaults to 6.2 percent | | Mortgage term | Years | 20 to 30 | Defaults to 30 years | | Income | AUD per year | Optional | Flagged when above AUD 100,000 in this model |
Worked Example
For a new-build home priced at AUD 600,000, a 2 percent deposit, a 6.0 percent interest rate, and a 30-year term:
- Deposit:
600,000 x 2% = AUD 12,000. - Government equity at 40 percent:
600,000 x 40% = AUD 240,000. - Mortgage:
600,000 - 12,000 - 240,000 = AUD 348,000. - Monthly rate:
6.0% / 12 = 0.5%, and the term is 360 months. - Amortization gives a repayment of about AUD 2,086 per month.
- A standard 95 percent loan on the same home would be AUD 570,000, repaying about AUD 3,417 per month, so the shared-equity structure saves about AUD 1,331 per month.
Interpreting the Results
The headline figure is the gap between the two repayments. A smaller mortgage means less interest over the life of the loan, but the government share is not a gift: when you sell, refinance, or buy out the equity share, the amount you repay tracks the property value at that time, so the government participates in price growth on its share. The calculator also flags the income field when it passes AUD 100,000, because the real scheme applies income caps that vary by household type and location. Treat the flag as a prompt to check eligibility, not as a final ruling. Because the equity portion carries no interest and no monthly fee in this Australian model, the year-six equity-loan fee output is zero; that fee concept belongs to the older United Kingdom scheme, not this one.
Choosing the Right Tool
Use the Mortgage Calculator when you already know your loan amount and want taxes, insurance, HOA fees, and a yearly amortization schedule included. Use the Borrowing Power Calculator when the open question is how much a lender may let you borrow from your income and debts. Use the Loan Calculator for a general-purpose loan repayment estimate outside a property purchase. Stay on this page when the decision you are modelling is specifically how a shared-equity split changes the deposit you need and the repayment you carry.
Questions
How much deposit do I need under this model?
The calculator defaults to a 2 percent deposit, which is the minimum deposit setting in the Australian Help to Buy design. On an AUD 600,000 home that is AUD 12,000, before stamp duty, legal fees, and other purchase costs, which are not included here.
Does the government charge interest on its equity share?
No. In this model the equity contribution is interest-free and has no monthly fee. You repay the share when you sell, refinance, or staircase out, and the repayment amount moves with the property value.
Can I enter a custom equity percentage?
Yes. Entering an equity loan percentage overrides the 30 or 40 percent defaults, which is useful for state-based shared-equity schemes or for testing what happens as you buy back part of the government share.
Limitations
Eligibility for the real Help to Buy scheme depends on income caps, property price caps that differ by state and region, citizenship and residency rules, and whether the property and lender qualify. None of those checks are performed here beyond the simple income flag. The repayment figures exclude stamp duty, lenders mortgage insurance, application fees, and ongoing property costs, and they assume a fixed rate for the full term, which variable-rate loans will not match in practice.
Sources and Methodology
The split percentages, deposit default, and income flag follow the Australian Government Help to Buy scheme design as modelled in this calculator, administered with state and territory governments and described by the Australian Government Treasury and Housing Australia. The repayment mathematics is the standard amortization formula used across the NerdyTools mortgage tools. Always confirm current scheme settings on the official Help to Buy pages before relying on an estimate.