Business Interruption Insurance Calculator
A fire, flood or other insured event does not just damage a building — it can stop a business trading entirely while repairs happen, and the lost income during that period is rarely covered by a standard property policy. Business interruption insurance is built specifically to replace that lost income, plus ongoing fixed costs like rent and salaries that keep running even while the doors are closed. This calculator estimates how much cover you would need and roughly what it might cost.
Business Interruption Insurance Estimator
Estimate the cost of Business Interruption (BI) insurance, which covers lost income if your business can't trade due to an insured event like fire, flood or theft.
Why This Cover Sits Alongside Your Property Policy, Not Instead Of It
Business interruption insurance is almost always bought as an extension to a commercial property or contents policy, not as a standalone product — it typically only pays out following the same type of insured event (fire, flood, escape of water, and similar) that your property cover responds to. Buying property cover without a business interruption extension is a common gap: the building gets repaired, but the income lost while it happened is never replaced, which can be the more financially damaging half of the loss for many small businesses.
This link to an underlying property claim is worth understanding clearly before assuming cover exists — a business interruption policy generally cannot be triggered on its own without a qualifying property damage event first occurring, even if trading has genuinely been disrupted for some other reason.
What “Lost” Actually Means for the Payout
Cover is based on gross profit, not simply revenue — broadly, your income minus the variable costs that stop when you stop trading, but before the fixed costs that keep running regardless. This distinction matters because fixed costs like rent, loan repayments and core salaries do not pause just because trading has stopped, so a policy needs to cover both the profit that would have been earned and the fixed costs that continue to be paid out during the interruption period.
Getting this figure right typically means working from actual accounts rather than a rough estimate — an accountant can usually help identify which costs genuinely stop during a closure and which continue, since this split is specific to how each individual business actually operates rather than a fixed formula that applies identically everywhere.
Choosing an Indemnity Period That Actually Fits
The indemnity period is the maximum length of time the policy will pay out for, and it needs to reflect realistic worst-case recovery time, not just how long a typical repair might take. A straightforward reinstatement might genuinely take a few months, but rebuilding a customer base, restocking specialist inventory, or dealing with planning permission for a significant rebuild can extend recovery well beyond that. Underestimating the indemnity period is one of the more common ways businesses end up underinsured — the cover runs out before trading has genuinely recovered to where it was.
A Simple Worked Example
A business with £150,000 in annual gross profit choosing a 12-month indemnity period needs cover of roughly £150,000 — the full amount it would stand to lose if trading stopped for a full year. Extending the indemnity period to 24 months, to reflect a more realistic worst-case rebuild and recovery timeline, doubles the required cover to £300,000, since the policy needs to be able to pay out for a full two years of lost profit if the maximum recovery scenario actually happens, not just a typical or best-case one.
The Sector Multiplier Nobody Explains
Not every business faces the same interruption risk at the same cost, which is why premium estimates vary by sector even for an identical amount of cover. Businesses with specialist equipment, long supply chains, or premises that are hard to quickly replace (a bespoke manufacturing unit, for example, versus a small retail unit that could realistically trade from a temporary unit) tend to see higher rates, reflecting a genuinely longer and more expensive realistic recovery scenario. This calculator applies a sector-based adjustment on top of the base rate for exactly this reason, rather than pricing every business identically regardless of what it actually does.
Combined policies that bundle business interruption with other commercial cover, such as buildings, contents and liability insurance together, can sometimes offer a modest discount over buying each element separately — worth asking about specifically when comparing quotes rather than assuming standalone pricing is always the cheaper route.
Business interruption cover is often reviewed alongside other business protections at the same time — our Employer Liability Insurance calculator covers the cover most UK employers are legally required to hold, and our Public Liability Insurance Calculator looks at cover for claims from members of the public, both of which are commonly reviewed as part of the same overall business insurance package.
Frequently Asked Questions
Does business interruption cover a global event like a pandemic?
This varies significantly by policy and was the subject of major disputes and court rulings following Covid-19. Some policies with specific disease or non-damage extensions did respond; many standard policies, tied to physical property damage, did not. Checking the exact wording of any non-damage extensions is essential rather than assuming cover exists.
Is loss of a single key customer covered?
Not under standard business interruption cover, which responds to insured physical events like fire or flood, not general commercial risks such as losing a client or a market downturn.
What happens if I am underinsured?
Many policies apply “average” — if your sum insured is lower than your actual exposure, a claim payout can be reduced proportionally, even for a partial loss, so reviewing your cover level as the business grows is genuinely important rather than a one-off exercise at setup.
Does cover include increased cost of working?
Many policies include this as standard or as an add-on — it covers reasonable additional costs incurred to keep trading during the interruption, such as temporary premises, provided those costs are less than the loss they prevent.
Can I insure for less than my full potential loss to save money?
You can choose a lower sum insured, but doing so risks being underinsured if a genuine claim arises, and many policies apply average in that situation, reducing the payout proportionally rather than simply capping it at the sum insured.
Do I need this if I work from home?
It depends on how the business operates — a home-based business with minimal reliance on physical premises may have less exposure than one dependent on stock, equipment or client-facing premises, but a serious event affecting your ability to work from home (such as a fire) can still cause a genuine interruption worth covering.
Important Information
This calculator provides an estimate for general information purposes only and does not constitute insurance advice or a quote. Actual cover requirements and premiums depend on your specific business, sector and circumstances, and should be confirmed with an insurer or broker. See our Disclaimer for further information.