Example result based on the prefilled values.
Usable Emergency Pot
£6,500.00
Monthly Shortfall to Fund
£1,600.00
Estimated Runway
4.06 months
Runway Status
Runway based on entered monthly shortfall
Gap to 3 Months of Essential Spending
£100.00
Gap to 6 Months
£6,700.00
Gap to 12 Months
£19,900.00
Continue your plan
Useful next calculations
Rates & sources
User-entered cash-runway model. Three and six months are shown as comparison points based on MoneyHelper guidance, not as a personalised savings recommendation.
Source: MoneyHelper — emergency savings — check the linked guidance and any live quote before acting.
When to use this calculator
- Before comparing lenders, brokers, or repayment options.
- When you want to test how a different deposit, rate, or term changes affordability.
- When you need a quick estimate before using a formal quote or agreement in principle.
- When you are stress-testing your budget against a potential rate rise to see the impact on monthly payments.
- When you want to understand the full cost of borrowing — not just the monthly figure — before you commit.
A realistic UK planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Accessible emergency savings (£)
£15,000
Net redundancy, insurance or other one-off support (£)
0
Immediate one-off emergency costs (£)
£500
Essential monthly spending (£)
6
After entering these figures, review usable emergency pot, monthly shortfall to fund and estimated runway together rather than in isolation — each metric tells a different part of the story. Then rerun the tool with one input adjusted to see which variable has the biggest effect on all three outputs before you settle on a plan.
How to read your results
Usable Emergency Pot
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Monthly Shortfall to Fund
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Estimated Runway
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Runway Status
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Gap to 3 Months of Essential Spending
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Gap to 6 Months
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Gap to 12 Months
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Method & assumptionsAuthoritative sources
This planner calculates the pot available after immediate one-off emergency costs, then divides it by the monthly shortfall between essential spending and reliable income or support. It reports when income covers the entered monthly need rather than inventing an infinite runway.
The three-, six- and twelve-month figures are neutral comparison points. MoneyHelper describes three to six months of essential outgoings as a rule of thumb, but a useful buffer depends on job security, health, dependants, insurance, housing and how quickly money can be accessed.
Do not count uncertain benefits, credit limits or volatile investments as guaranteed cash. If priority bills may be missed, seek free debt or benefits guidance promptly. This tool does not assess entitlement, insurance claims or whether savings should be used ahead of debt repayment.
Common mistakes
- !Mixing up loan amount and property value, which can distort affordability and LTV.
- !Using a headline rate but forgetting fees, insurance, taxes, or repayment type.
- !Testing only one term length instead of comparing the payment and total cost together.
- !Forgetting that a repayment mortgage and an interest-only mortgage produce very different monthly figures and total costs.
- !Not accounting for the impact of a rate revert after an introductory fixed period ends, which can sharply increase payments.
What to do next
- Run a second scenario with a higher rate or shorter term so you can see the downside clearly.
- Compare the result with an affordability or overpayment calculator before applying.
- Use the related guides below to understand trade-offs before you request live quotes.
- Note down the monthly payment and total interest for your two or three strongest scenarios so you have a clear comparison ready when you speak to a broker.
- Check whether making a modest overpayment each month would reduce total interest significantly — run the overpayment calculator next to find out.
Frequently asked
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