TL;DR
For a fast estimate of how much you could borrow, use the Calc Garden mortgage affordability calculator: enter your income, pick a lending multiple and add your deposit, and it shows your maximum loan and property price the instant you type, with the income-multiple method on the page and no signup. If you want a fuller check that factors your monthly outgoings, the government-backed MoneyHelper calculator is the most thorough free option. This is not an "only free one" claim: MoneyHelper, MoneySavingExpert and the bank calculators are all free too. The choice is really quick estimate versus detailed budget check versus a specific lender's numbers.
What a mortgage affordability calculator actually does
An affordability calculator answers one question: roughly how much could a lender let you borrow? Almost every UK version starts from the same rule, the income multiple. Lenders cap most mortgages at around 4 to 4.5 times your annual income, with a few stretching to 5 times for strong applicants, so the core sum is your income multiplied by that figure. Add your deposit and you get the top property price you could reach, because price equals loan plus deposit.
Because that arithmetic is shared, the tools differ on what they wrap around it. Some ask only for income and a multiple and hand back a number in seconds. Others ask for your monthly outgoings and give a budget-aware range. Some are run by a specific bank and quietly tune the answer to their own lending rules. The table below lines up four free options on exactly these points so you can pick by what you actually need rather than by brand.
The best free mortgage affordability calculators compared
In the table a check means the tool does it cleanly, "Partial" means it does it with caveats, and a dash means it does not. The pricing row reflects each product as of 2026.
| Capability | Calc Garden | MoneyHelper | MoneySavingExpert | Bank calculators |
|---|---|---|---|---|
| Price (as of 2026) | Free, no signup | Free, no signup | Free, no signup | Free, no signup |
| Instant estimate as you type | Yes | Partial | Partial | Partial |
| Only needs income, multiple and deposit | Yes | No | Partial | No |
| Factors your monthly outgoings | No | Yes | Partial | Yes |
| Shows top property price from deposit | Yes | Partial | Partial | Partial |
| Lender-neutral (not tied to one bank) | Yes | Yes | Yes | No |
| Income-multiple method shown on the page | Yes | Partial | Partial | No |
| Runs client-side in your browser | Yes | No | No | No |
Read it honestly. MoneyHelper wins where it counts for a realistic budget: it asks for your income and your monthly commitments, then shows a borrowing range, an estimated monthly repayment and what you would have left each month, which a plain income-multiple tool cannot do. It is run by the Money and Pensions Service, so it is impartial and free. MoneySavingExpert is strong if you want to move from an estimate straight to live best-buy deals, since its calculator sits alongside its mortgage comparison tables. The bank calculators are useful once you are close to applying, because each shows what that specific lender might offer. Calc Garden wins on speed and clarity for the first question of all: given my income and deposit, what is my ballpark ceiling, shown with the method rather than a hidden formula.
Why a simple, no-signup estimate often comes first
Early in a house search the question is usually broad: on my income, what price bracket am I even looking at? For that, a full budget questionnaire or a single lender's form is more machinery than the question needs. You want a number fast, so you know whether to browse at 200,000 pounds or 350,000 pounds before booking a call with a broker.
Calc Garden's mortgage affordability calculator runs entirely in your browser. Enter your income and any partner income, choose a multiple, and add your deposit. It multiplies income by the multiple to get a maximum loan, then adds the deposit for the top property price, updating live as you change any input. Nothing is sent to a server and there is no signup. The trade-off is honest and worth stating: it does not model your monthly outgoings, so once you have a target price, the MoneyHelper tool or a broker gives the affordability detail a lender will actually test.
How the income-multiple method works by hand
The core sum is income multiplied by a lending multiple. Take a combined household income of 60,000 pounds. At 4.5 times, the maximum loan is 270,000 pounds. Add a 40,000 pound deposit and the top property price is 310,000 pounds. Change the multiple to 4 times and the loan drops to 240,000 pounds, showing why the multiple a lender applies matters as much as your income.
Two caveats keep the estimate honest. First, the multiple is not fixed: lenders set it case by case, and existing debts, childcare costs or a short remaining working life before retirement can pull it down. Second, passing the income-multiple cap is not the same as passing affordability. A lender also stress-tests whether you could still pay if rates rose, so the real offer can be lower than the multiple suggests. Use the income-multiple figure as the ceiling to sense-check, then confirm the monthly cost with a repayment tool.
When to pick each one
Reach for MoneyHelper when you want a budget-aware borrowing range that factors your outgoings, or MoneySavingExpert when you want to jump from an estimate to live deals. Reach for a specific bank's calculator when you are close to applying and want that lender's own indication.
Reach for the Calc Garden mortgage affordability calculator when you want a fast, lender-neutral ballpark with the method shown and nothing to sign up for. Once you have a target price, two related tools finish the job: the mortgage repayment calculator shows the monthly payment and total interest at a given rate, and the debt-to-income ratio calculator checks how the new payment sits against your income. For the wider set of explainers, the guides index collects the rest, including the best free mortgage calculator that shows total interest.