This shared ownership mortgage calculator works out your total monthly cost when you buy part of a home and pay rent on the rest. Enter the full value, the share you buy and your deposit, and it adds up the mortgage, rent and service charge.
Your shared ownership costs
- Your share
- –
- Mortgage a month
- –
- Rent a month
- –
- Total a month
- –
In the example, a 40% share of a £300,000 home costs £120,000. With a 10% deposit and a 4.8% mortgage, the mortgage is £618.84 a month, rent on the other 60% is £412.50 and the service charge is £120, a total of £1,151.34.
How to use the shared ownership mortgage calculator
- Enter the full market value of the home.
- Choose the share you will buy, usually between 10% and 75%.
- Enter your deposit as a percentage of your share, and the mortgage rate and term.
- Enter the rent rate and the monthly service charge from the property details.
How shared ownership works
You buy a share of a home from a housing association or council, take a mortgage on that share and pay rent on the rest. You need a household income under £80,000 (£90,000 in London) in England. See GOV.UK shared ownership.
Rent is usually up to 3% a year of the value of the share you do not own, and it normally rises each April. You are also responsible for service charges and, after any initial repair period, for repairs.
Shared ownership examples
| Share | Share value | Mortgage | Rent | Total a month |
|---|---|---|---|---|
| 10% | £30,000 | £155 | £619 | £893 |
| 25% | £75,000 | £387 | £516 | £1,022 |
| 40% | £120,000 | £619 | £412 | £1,151 |
| 50% | £150,000 | £774 | £344 | £1,237 |
| 75% | £225,000 | £1,160 | £172 | £1,452 |
Buying a bigger share means a bigger mortgage but less rent. Use the shared ownership mortgage calculator to find the mix that suits your budget.
Staircasing
Staircasing means buying more shares later, until you own 100%. Each share is priced at the market value at the time, so if prices rise, later shares cost more. Under the newer model, you can buy extra shares in 1% steps for the first 15 years.
Things to check
- Lease length and any restrictions on selling or subletting.
- How rent increases are worked out.
- Service charge history and planned major works.
- Which lenders offer shared ownership mortgages for the scheme.
Related calculators
Plan your savings with the mortgage deposit calculator, and check what you take home with the monthly take home pay calculator.
Shared ownership mortgage calculator: worked example
Priya and Sam earn £55,000 between them and want a £300,000 flat. They cannot raise a 10% deposit on the whole price, so they buy a 40% share for £120,000 with a £12,000 deposit. The shared ownership mortgage calculator shows a monthly cost of £1,151.34, including rent and service charge. Five years later, if the flat is worth £330,000, buying another 25% would cost £82,500.
Always compare the total with renting a similar home and with buying a cheaper home outright on the open market.
Frequently asked questions
Is shared ownership cheaper than renting?
Often the monthly cost is similar to or lower than private rent, and you build some equity. But you also pay service charges and, eventually, repairs.
How much deposit do I need for shared ownership?
Usually 5% to 10% of the share you buy, not of the full value. On a 40% share of £300,000, a 5% deposit is £6,000.
Can I sell a shared ownership home?
Yes. The housing association usually has the first chance to find a buyer for a set period, after which you can sell on the open market.
Does the rent go up?
Usually once a year in line with inflation (CPI or RPI plus a small percentage), as set out in your lease.
About this calculator
This shared ownership mortgage calculator uses the standard repayment formula. Scheme rules were checked against GOV.UK on 9 November 2026. Results are estimates.