Underinsurance calculator
Check whether your current sum insured is likely to be adequate, and estimate what could happen to a claim if the average clause applies.
Use our rebuild cost or contents calculator to estimate this.
A hypothetical claim to illustrate the impact.
Check your policy wording — not all policies apply this clause.
Assumptions and methodology
Adequacy % = current sum insured / estimated true value. If average clause applies: potential claim payment = example claim × adequacy %. Shortfall = example claim − potential payment. Whether the average clause applies depends on your specific policy wording — check your policy.
Common mistakes to avoid
- ✕Insuring buildings for market value rather than rebuild cost — often leads to over-insurance.
- ✕Underestimating contents value and then being surprised when a claim is reduced.
- ✕Not reviewing the sum insured annually — rebuild costs and contents values change over time.
- ✕Assuming the average clause doesn't apply without checking the policy wording.
Frequently asked questions
The average clause (also called 'condition of average') allows the insurer to reduce a claim payout in proportion to the degree of underinsurance. If you are insured for 70% of the true value, the insurer may only pay 70% of your claim.
Not always — it depends on the policy wording. Some policies, particularly higher-end home insurance products, do not apply the average clause. Check your policy schedule and wording carefully.
Contact your insurer or broker immediately to update your sum insured. For buildings, use a professional rebuild cost assessment for an accurate figure. For contents, carry out a room-by-room inventory.
Related calculators
Home insurance
Rebuild Cost Calculator
Get a rough estimate of your home's rebuild cost — which is not the same as its market value.
Home insurance
Contents Insurance Calculator
Build up an estimate of what your home contents are worth to replace.
General tools
Insurance Premium Tax Calculator
Add or extract Insurance Premium Tax at the standard (12%) or higher (20%) UK rate.
Disclaimer
This is a simplified estimate based on the assumptions shown above. It isn't a quote, and a real insurer may arrive at a different figure. Use it as a starting point, then check the details with your insurer or adviser.