Business Interruption Loss Calculator

How to Use This Tool

Follow these steps to get accurate interruption loss estimates:

1. Enter your average monthly revenue from the 3 months before the interruption.
2. Input the total number of days your business was fully or partially closed.
3. Add your monthly fixed costs (rent, salaries, subscriptions, utilities) that continued during downtime.
4. Enter any variable costs you saved during closure (raw materials, shipping, hourly labor) if applicable.
5. Add any insurance coverage you expect to receive for the interruption.
6. Optionally include the number of days you expect to take to return to full revenue after reopening.
7. Click Calculate Loss to see your detailed breakdown.

Formula and Logic

We use standard business interruption calculation methods aligned with insurance industry practices:

• Daily Revenue = Monthly Average Revenue / 30
• Total Lost Revenue = Daily Revenue × Downtime Days
• Total Fixed Costs During Downtime = (Monthly Fixed Costs / 30) × Downtime Days
• Net Operating Loss = Total Lost Revenue + Total Fixed Costs − Variable Cost Savings
• Final Net Loss = Net Operating Loss − Insurance Coverage
• Recovery Period Loss = (Daily Revenue × 0.5) × Recovery Days (assumes 50% revenue capacity during ramp-up)
• Total Overall Loss = Final Net Loss + Recovery Period Loss

All currency values are formatted using your selected currency. You can adjust the recovery loss assumption in your own records if your ramp-up period has different revenue recovery rates.

Practical Notes

These business-specific tips help you apply results to real-world scenarios:

• Keep 3-6 months of fixed cost reserves to cover downtime, as most SMBs lack sufficient cash flow for unplanned closures.
• E-commerce sellers should include lost marketplace ranking and ad spend waste as additional variable losses not captured here.
• Insurance policies often require documentation of lost revenue (tax returns, POS records) to approve claims — use this tool’s breakdown to support your submission.
• Partial downtime (e.g., reduced hours) should be counted as 0.5 days per day of reduced operation for rough estimates.
• Seasonal businesses should use monthly revenue from the same quarter in the prior year for more accurate calculations.

Why This Tool Is Useful

Business interruption losses are often underestimated, leading to cash flow crises or underpaid insurance claims. This tool helps:

• Small business owners quantify exact financial impact to adjust emergency budgets.
• E-commerce sellers calculate lost sales from platform outages or supply chain delays.
• Entrepreneurs prepare risk assessments for investors or lenders.
• Operations teams identify high-risk fixed costs to reduce in contingency planning.

Frequently Asked Questions

What counts as a business interruption?

Qualifying interruptions include natural disasters, utility outages, supply chain failures, cyberattacks, or mandatory closures. Partial disruptions like reduced hours or staff shortages also count if they reduce revenue.

How do I value variable cost savings?

Only include costs that you would have incurred if operating normally but did not pay during downtime. Do not include costs you would have paid regardless, like retainer fees for contractors.

Is recovery period loss mandatory to include?

No, you can leave the recovery days field blank if you expect to return to full revenue immediately after reopening. The 50% revenue assumption is a standard industry benchmark, but you can adjust calculations manually if your ramp-up is faster or slower.

Additional Guidance

For the most accurate results, use financial data from your accounting software rather than estimates. If you have multiple revenue streams, calculate interruption loss for each stream separately then sum them. Always cross-check insurance policy terms to confirm which losses are covered — some policies exclude lost profits from partial downtime. Review your results with a certified public accountant if the loss exceeds $10,000 to ensure tax deductibility.