Business Interruption Insurance Claim Calculator

How to use: estimating a business interruption insurance claim

This calculator gives you a planning-level estimate of the business interruption insurance claim that may follow a covered shutdown such as a fire, storm damage, burst pipe, or equipment failure. It translates lost revenue, continuing expenses, and extra expenses into one estimate, then trims the result by the waiting period in your policy.

To keep the math practical, the tool uses your average revenue and cost structure before the interruption and applies those figures across the downtime that remains after the waiting period. The result is meant to help you frame conversations with your insurance professional, broker, or claims adjuster when you are trying to understand the size of the loss.

Key business interruption claim concepts and formulas

The calculator treats a business interruption claim as a blend of lost gross profit, continuing fixed expenses, and qualifying extra expense, then applies those pieces across the covered days.

1. Lost revenue during downtime

Average revenue per day before loss is multiplied by the number of days you cannot operate, which the calculator calls your covered downtime.

Covered downtime is:

Formula: Covered\ Downtime = Total\ Downtime − Waiting\ Period

If the waiting period is the same as or longer than the total downtime, the calculator treats the covered downtime as zero because no business interruption period remains after the deductible time is applied.

2. Variable costs and gross profit

Variable costs are the expenses that generally shrink when revenue shrinks, such as raw materials, shipping tied to sales, and some hourly labor. In this calculator, they are entered as a variable cost rate that acts as a percentage of revenue.

Estimated variable costs during covered downtime are calculated as:

Formula: Variable\ Costs = Average\ Revenue\ per\ Day × Covered\ Downtime × (Variable\ Cost\ Rate) / 100

Lost gross profit is then estimated by subtracting the variable costs you would not have incurred from the revenue you would have earned during the covered shutdown.

3. Continuing fixed expenses

Continuing fixed expenses per day are the bills that keep showing up even while your business is closed or partially closed. In a business interruption claim, these often include rent, salaried payroll, minimum utilities, loan payments, and insurance premiums.

The calculator multiplies your daily continuing fixed expenses by the covered downtime so you can see how much of those fixed costs may still need to be carried during the interruption.

4. Extra expenses

Extra expenses are the additional costs you take on to shorten the interruption or reduce the size of the loss, such as renting temporary space, outsourcing production, or paying expedited shipping to keep orders moving. You can enter those qualifying costs as a total, and the tool adds them to the estimate.

Understanding your estimated business interruption claim

The output of the calculator is an estimated business interruption claim amount based on the pieces above. In simple terms, it is:

• Lost gross profit during the covered downtime, plus
• Continuing fixed expenses that still had to be paid, plus
• Extra expenses you chose to incur to reduce or avoid a larger loss.

Use the result as a directional planning figure, not as a guaranteed payout. Actual claim payments depend on your policy wording, coverage limits, sublimits, exclusions, deductibles, proof-of-loss documentation, and how the insurer evaluates the facts of your interruption.

If the number looks unexpectedly high or low, try adjusting:

• Average revenue per day: Use a different historical window, such as the last three months or the last twelve months, or exclude unusual spikes that are not representative of the shutdown period.
• Variable cost rate: Include only the costs that truly disappear when sales stop; items that stay in place should be treated as fixed expenses instead.
• Downtime and waiting period: Match these to the dates your operations were actually interrupted and to the waiting period written into the policy.
• Extra expenses: Include only additional costs that were tied to reducing the interruption, not expenses you would have paid anyway in normal operations.

Worked example: estimating a retail business interruption claim after a 14-day closure

Imagine a retail business with the following interruption:

• Average revenue per day before loss: $5,000
• Variable cost rate: 40%
• Continuing fixed expenses per day: $500
• Total downtime: 14 days
• Waiting period: 3 days
• Total extra expenses: $8,000 (temporary location and rush shipping)

First, calculate the covered downtime:

Covered downtime = 14 days total downtime − 3 day waiting period = 11 days.

Next, estimate lost revenue:

Lost revenue = $5,000 × 11 = $55,000.

Then estimate variable costs that would have been incurred to earn that revenue:

Variable costs = $55,000 × 40% = $22,000.

Lost gross profit is then approximately:

Lost gross profit = $55,000 − $22,000 = $33,000.

Continuing fixed expenses during covered downtime are:

Fixed expenses = $500 × 11 = $5,500.

Finally, add extra expenses:

Total estimated impact = $33,000 (lost gross profit) + $5,500 (fixed expenses) + $8,000 (extra expenses) = $46,500.

The calculator will produce an estimate in this range based on your inputs. An insurer may calculate certain elements differently, and policy terms can significantly change the final covered amount.

Comparison: what this business interruption claim calculator includes and leaves out

Assumptions and limitations for business interruption claims

This business interruption estimator is intentionally simplified so it can stay fast and understandable. It is meant for education and planning, not for preparing a formal proof of loss. The main assumptions are:

• Linear relationship between revenue and downtime: The calculator assumes every covered day reduces revenue by the same average amount, without a separate ramp-up period or seasonal curve.
• Single variable cost rate: All variable costs are grouped into one percentage of revenue. Real operations often have costs that behave differently at different sales levels.
• No policy-specific adjustments: The tool does not apply coverage limits, sublimits, exclusions, coinsurance clauses, period-of-indemnity rules, or special endorsements unless you manually reflect those items in your inputs.
• No taxes, financing, or salvage value: The estimate does not model tax effects, financing arrangements, or salvage or resale value from damaged goods.
• Data quality matters: The estimate is only as useful as the revenue, expense, and downtime figures you choose to enter.

Important: This calculator is for informational and educational purposes only. It is not legal, tax, or financial advice, and it does not guarantee coverage or payment under any insurance policy. For decisions about coverage, claim filing, or documentation, consult a licensed insurance professional, accountant, or attorney familiar with your situation.

When this business interruption claim calculator is most useful

You may find this tool especially helpful when you want to:

• Estimate the potential size of a business interruption claim shortly after a loss so you can understand the likely financial pressure on the business.
• Prepare for discussions with your insurance broker, risk manager, public adjuster, or claims adjuster.
• Compare different downtime scenarios, such as a shorter closure versus a longer one that may push the claim far beyond your cash reserves.
• Stress-test whether your current business interruption limit may be too low or too high for the size of the interruption.

For broader planning, you can use this estimate alongside your financial statements, cash-flow projections, and recovery timeline so you have a clearer picture of what the interruption may cost. A careful estimate is often more useful than a rough guess when you are deciding how quickly to reopen, what extra expenses are worth incurring, and whether the policy limit appears adequate.

Introduction: Why Business Interruption Claims Are Hard to Estimate

When a fire, flood, equipment failure, or another covered event shuts a business down, the visible damage may be obvious: a burned kitchen, a broken HVAC unit, or a water-soaked retail floor. The financial damage is less visible. While you repair the physical problem, revenue drops or stops, but many expenses continue. Employees still need to be paid, leases still accrue, software subscriptions still renew, and debt payments still come due. Business interruption insurance is designed to bridge that gap by replacing lost income so the business can survive the interruption and reopen.

Even so, business interruption claims are notoriously difficult to estimate. Policies use terms like business income, period of restoration, continuing expenses, and extra expense. Coverage often starts only after a waiting period. Some expenses are covered, others are not. Insurers may ask you to show what your revenue would have been but for the loss, which means comparing historical performance, seasonality, and the way your business normally ramps up or slows down. Small businesses often underestimate the claim because they focus on gross revenue alone rather than lost profit plus continuing costs. Others overestimate by counting expenses that would have stopped anyway. A clear model helps you avoid both mistakes.

This calculator provides a practical, transparent estimate. It is not a substitute for a forensic accountant, and it does not interpret policy language for you. But it does show the core arithmetic that sits behind many business interruption claims and gives you a starting point for conversations with your insurer.

What Business Interruption Insurance Typically Covers

Most business interruption policies cover two main buckets during the period of restoration, which is the time it takes to repair or replace the damaged property and resume operations:

• Lost business income. This is the profit you would have earned if the loss had not happened. Policies usually define it as net income plus continuing normal operating expenses.
• Continuing expenses. These are fixed costs that still occur even if you cannot operate, such as rent, utility minimums, key staff payroll, and loan interest.

Many policies also include extra expense coverage: reasonable additional costs you incur to reduce the interruption, such as renting temporary space, paying overtime to speed repairs, or leasing replacement equipment. Extra expense coverage can be a separate limit or part of the business income limit, so the policy wording matters as much as the arithmetic.

The Core Claim Formula

A simplified business income loss model starts with gross revenue, subtracts variable costs that would not have been incurred during shutdown, then adds continuing expenses and extra expenses. Let:

• R = average revenue per day before the loss
• v = variable cost rate (% of revenue that disappears when revenue disappears)
• F = continuing fixed expenses per day
• E = extra expenses per day (or total extra expenses)
• d = number of downtime days
• w = waiting period days (policy deductible in time)

Then covered days are max(0, d − w). The daily lost profit is revenue times (1 − variable rate). The basic claim estimate is:

This formula mirrors the common business interruption idea of net income plus continuing expenses, plus any qualifying extra expense.

Worked example: bakery claim with a 72-hour waiting period

Imagine a neighborhood bakery that averages $2,400 of revenue per day. About 45% of that revenue is variable cost, mainly ingredients, packaging, and hourly staff that can be scaled back. The bakery’s continuing fixed expenses—rent, insurance, a salaried manager, and basic utilities—are about $600 per day. A kitchen fire closes the shop for 28 days. The policy has a 72-hour (3-day) waiting period. The owner spends $4,500 in extra expense renting a temporary commissary so wholesale orders can continue.

Covered days are 28 − 3 = 25 days.

Daily lost profit is $2,400 × (1 − 0.45) = $1,320.

Daily business income loss plus continuing expenses is $1,320 + $600 = $1,920.

Loss for covered days is 25 × $1,920 = $48,000.

Add extra expenses of $4,500 for a total claim estimate of $52,500.

An insurer may adjust this for seasonality, for example if the fire happened during the holiday rush, but the baseline math is the same.

Comparison Table: What usually counts in a business interruption claim

Period of Restoration and “Waiting Period”

Business interruption coverage is tied to time, and timing can change the claim materially. Two time concepts matter:

• Waiting period. Often 48–72 hours. Losses during the waiting period are not covered, which is why the calculator subtracts waiting days from downtime days.
• Period of restoration. The period during which the insurer will pay for lost business income, usually from the date of loss until the property is repaired and the business can resume operations, or should have been able to resume using reasonable speed and due diligence.

In practice, insurers sometimes challenge the length of the restoration period if they believe repairs could have been completed faster. Document supply-chain constraints, permitting delays, and contractor scheduling. If you can partially reopen, your claim may shift from total interruption to partial interruption, where reduced revenue is compared against the but-for baseline rather than a complete shutdown.

Seasonality and the “But‑For” Revenue Baseline

Many businesses are seasonal. A landscaping company loses more in spring than in winter; a toy store loses more in November and December; a hotel’s revenue depends on events and local tourism. Business interruption claims usually require a but-for estimate of what revenue would have been during the downtime. A practical approach is to compare:

• Same weeks or months from the prior year.
• Trailing 3–12 month average adjusted for trend.
• Bookings on the calendar for appointment-based businesses.

This calculator uses an average revenue per day input, which works well if you choose a baseline that is representative of the affected period. If the closure falls during a peak season, use a peak-season average rather than an off-season number so the estimate does not understate the interruption.

Documentation Checklist

Business interruption claim files are stronger when the revenue baseline and extra expenses are documented clearly. A short checklist helps:

Policy limits and coinsurance can still cap a business interruption claim

Many policies have a business income limit, sometimes expressed as a dollar amount or as a period of coverage such as 12 months, and some also include coinsurance requirements that can penalize underinsuring. This estimator does not apply those provisions because they vary widely from one policy to another. If your policy has a stated limit, treat the estimate as capped at that limit. If your policy has coinsurance, compare your reported business income values to the required percentage so you are not surprised later.

Limitations and Assumptions for this business interruption claim estimator

This calculator uses a compact model so it works for many business types. It assumes:

• Revenue before loss is a reasonable proxy for but-for revenue during the interruption, with no explicit seasonality model.
• Variable costs scale linearly with revenue.
• Continuing fixed expenses are stable per day.
• Extra expenses are entered as total qualifying costs.
• Policy limits, coinsurance requirements, and sub-limits are not applied.

To refine a real business interruption claim, document daily sales history, compare it with prior-year periods, and keep receipts for every extra expense you intend to claim. Many businesses also hire a public adjuster or forensic accountant to negotiate policy interpretations and to support the numbers that go into the proof of loss. Even with those steps, the estimate here is still a useful, transparent starting point.