The formula
How to calculate insurance payout
A claim rarely pays the full value of the loss. The excess comes off every settlement, and if the sum insured is below the true value of what you insured, the average clause reduces the payout by the same proportion.
The average clause catches people who insure a £100,000 rebuild for £80,000 to save on premium. Claim £12,000 and the insurer pays 80% of it — the shortfall applies to small claims, not just total losses.
What to enter:
- Value of the loss
- Sum insured
- True value of the property insured
- Policy excess
Results appear immediately — there is nothing to submit. Changing a field rewrites the link, so you can share the exact scenario you are looking at.
Where a figure is not immediately to hand — a precise interest rate, an exact balance — a reasonable estimate is a perfectly good starting point. Because every result updates instantly, refining a rough guess into the real figure once you have it takes a moment, and nothing about the calculation depends on getting it exactly right on the first attempt.
Why insurance payout matters
Most people who look up a insurance payout calculation already have a specific number in mind — a quote, an offer, a target — and want to check it rather than learn the theory behind it. This page is built for that: enter your own figures, see the result immediately, and change any field to see how the answer moves without redoing the arithmetic from scratch each time.
Beyond a one-off check, the same calculation is worth revisiting whenever the underlying numbers change — a new interest rate, a change in income, a different term. Because the figures live in the page's own web address, coming back to update just one field and compare the new result against the old one takes seconds rather than starting again from a blank page.
The reason a page like this exists at all, rather than leaving the calculation to a spreadsheet or a textbook appendix, is that the formula behind insurance payout is fiddly enough to get wrong by hand but not complicated enough to need specialist software. That middle ground — real enough maths to matter, simple enough to check instantly — is exactly what a dedicated calculator is for, and it is why the same figure recalculated here should match a careful manual calculation almost exactly.
Where the same calculation needs to be run for several different scenarios side by side — three loan offers, two savings plans — the fastest approach is usually to open the calculator in a second browser tab for each one, so that the results can be compared directly rather than overwriting each other in a single set of fields.
Worked example
A concrete run-through, using the values already in the fields:
- Value of the loss: 12,000
- Sum insured: 80,000
- True value of the property insured: 100,000
- Policy excess: 500
That gives:
- Likely payout: 9,100
- Reduction for underinsurance: 2,400
- Total you are left to fund: 2,900
These figures are only the calculator's own starting values, included so the working is visible rather than hidden inside the tool above. Replace them with your own numbers and the same arithmetic applies — nothing about the method changes, only the inputs feeding it.
Reading the result
The reduction line shows what underinsurance costs on this one claim. Compare it against the premium saved: the saving is usually a few tens of pounds a year against thousands at the point of claim.
Where this goes wrong. Insuring a building for its market value. Buildings cover should be the rebuild cost, which excludes land and can be well above or below what the property would sell for.
A useful check on any unfamiliar result is to compare it against a rough mental estimate first — round the inputs to convenient numbers and see whether the calculator's answer lands in roughly the same territory. A wildly different figure usually means one of the fields was entered in the wrong unit, most often a percentage typed as a whole number where a decimal was expected, or the reverse.
A standard policy condition that reduces claims in proportion to any underinsurance. Insure 70% of the true value and the insurer pays 70% of each claim, however small.
A higher voluntary excess lowers the premium and is sensible if you could comfortably cover it. Setting it above what you could pay on short notice defeats the purpose of the insurance.
The headline figure is likely payout. With 12,000 value of the loss, 80,000 sum insured and 100,000 true value of the property insured, that comes to 9,100. Change any field and the figure moves with it.
Whenever one of the underlying figures changes — a new interest rate, a different balance, an updated term — since the result only reflects what is currently in the fields. There is no need to keep a separate record of past results; the web address for a filled-in version already carries the figures used to produce it.
Not unless a tax rate or a fee is explicitly one of the inputs above. Where it is not, the figure shown is a gross calculation, and any tax due depends on your personal circumstances and current tax rules, which are worth checking separately.
The arithmetic itself is exact — the calculator applies the formula shown above precisely, with no rounding until the final figure is displayed. The uncertainty, where it exists, is entirely in the inputs: an estimated rate or an approximate balance carries that same approximation through to the result.