What average does to a claim
Enter a sum insured and a rebuild cost to see how underinsurance cuts a payout, with the working shown at each step.
Look up average →Tools that show their working
Each calculator here runs a real insurance question, such as what average does to a partial claim or which covers a trade needs by law, and it shows the method behind the number. A tool built on a general rule can still give the wrong answer for your own policy wording, so check the working before you rely on it.
Read the claim stories behind these numbers in the Claims Story Library See the reasoning explained in full in the Business Insurance GuidesRun the numbers on your own cover
Each tool works through a real insurance calculation, average, statutory cover or indemnity period, and shows its method so you can check the result yourself.
Cover your trade needs by law
A checklist of statutory and contractual cover requirements by trade, with the source named for each entry.
Read what each cover does →How long recovery actually takes
Work out whether a stated indemnity period would have covered a real rebuild, using a case where it did not.
See the flood claim →What raising your excess saves
Compare premium and excess figures side by side to see what a higher excess actually costs you at claim time.
See how quotes are built →How these tools work
Each tool on this page runs a real calculation or checks against a real statutory list, and shows the working. A calculator that only prints an answer asks you to trust it; one that shows the sum insured, the value at risk and the reduction applied lets you check the arithmetic against your own figures. A checklist that only lists ticks asks the same trust of you; one that names the Act or policy condition behind each item lets you go and read the source for yourself.
What the calculators answer
Underinsurance is usually explained as a warning against a vague danger. Here it is worked as arithmetic: put in the sum insured and the value actually at risk, and the tool applies the reduction an insurer would apply to a partial claim, showing why the payout falls short and by how much (the mechanism is called the average clause, and it is explained further on the glossary page). A separate calculator works the same way for an indemnity period, taking the figures you supply and showing whether twelve months of business interruption cover would see a rebuild through to completion.
What the checklists answer
Some cover is not optional in the way a shop chooses its stock cover. The employers' liability checklist works from the Employers' Liability (Compulsory Insurance) Act 1969, which sets a £5 million minimum, noting that most policies in practice are written well above that floor. Other checklists work from trade-specific duties, such as what a commercial lease commonly requires a tenant to carry, or what a construction contract requires of a subcontractor. Each checklist names its source so the requirement can be checked independently of the tool that lists it.
What a tool cannot do
A calculator built on a general formula can still give a wrong answer for a policy that departs from the general case, because wording varies between insurers and the clause in front of you may not be the one the tool assumes. Treat every result as a reason to open your own policy schedule and check the figure against it. The guides on this site set out how each cover and each clause works in more detail than a calculator has room for, and the guides index is the place to start reading further.