Coinsurance penalty calculator
Compare the insurance carried with the amount required, then see how a proportional payment changes the result.
Start with the policy
Enter the same valuation basis on both sides
This illustration compares the value, required amount, carried limit, loss, and deductible you enter. It is not a coverage opinion.
Enter the value used by the policy for the selected valuation basis.
Value and limit must share one basis for this illustration.
Choose the percentage stated in the policy or enter a custom percentage to review.
Enter the limit shown for the property and valuation basis being tested.
Enter the loss amount you want to compare with the required amount.
Enter the deductible that the policy applies to this loss.
Turn this on only when the policy has an agreed-value option in force; read the endorsement.
Use this only when a blanket schedule and margin clause apply to the building being illustrated.
What-if carried-limit comparison
Test a different carried limit without changing the worksheet's limit, permalink, or primary result. This separate illustration uses the same property value, percentage, loss, deductible, and policy options.
Enter a comparison limit only. It is not saved in the worksheet or shared link.
Illustrated result
Enter a property value greater than zero and review the required fields to see the illustration. The calculator does not fill in a policy value for you.
Related tools and reading
Frequently Asked Questions
What does the required amount mean?
It is the property value multiplied by the coinsurance percentage entered here. The valuation and limit must use the same basis.
Does this calculator decide coverage?
No. It illustrates the requested arithmetic. The policy wording, endorsements, and facts of the loss control.
Why is there an agreed value toggle?
It lets you compare a policy option that may remove the penalty. Confirm whether the option is actually in force before relying on the comparison.
What record supports the property value?
Use the valuation report, appraisal, schedule, inventory, or other record that supports the value at the time of loss.
Policy provisions · Last reviewed September 16, 2026
- ISO CP 00 10, Coinsurance condition: multiply the loss by carried insurance divided by required insurance (ratio capped at 1), subtract the deductible, floor at zero, then cap at the limit of insurance. An applicable margin cap may further limit payment. No loss-threshold shortcut applies. Last reviewed September 16, 2026.
Supporting Records Needed
- Declarations page or schedule for the limit carried and deductible
- Policy valuation wording and any current valuation report
- Loss estimate, inventory, or repair scope supporting the loss amount
- Any agreed-value endorsement and statement-of-values schedule
Related Reading
Educational illustration based on your inputs. Not legal, coverage or claim advice. Your policy language controls.
Coinsurance penalty calculator Summary
Generated on
The linked URL in a saved PDF reopens these inputs. The worksheet values are printed below.
Inputs
| Property value at loss | $0.00Source: Value entered by the user; read the applicable wording in your policy. |
| Valuation basis | Replacement costSource: The valuation basis selected by the user; read the applicable wording in your policy. |
| Coinsurance percentage | 80%Source: The coinsurance percentage selected by the user; read the applicable wording in your policy. |
| Limit carried | $0.00Source: The limit entered by the user; read the applicable wording in your policy. |
| Loss | $0.00Source: The loss estimate entered by the user; read the applicable wording in your policy. |
| Deductible | $0.00Source: The deductible entered by the user; read the applicable wording in your policy. |
| Agreed value option | Not selectedSource: The option selected by the user; read the applicable wording in your policy. |
| Blanket mode | OffSource: The blanket mode selected by the user; read the applicable wording in your policy. |
| Margin clause percentage | Not usedSource: The margin percentage entered by the user, when blanket mode is on; read the applicable wording in your policy. |
| Selected building | Not usedSource: The selected statement-of-values row, when blanket mode is on; read the applicable wording in your policy. |
| Statement of values - Building 1 | $0.00Source: The statement-of-values row entered by the user; read the applicable wording in your policy. |
Results
Policy provisions · Last reviewed September 16, 2026
- ISO CP 00 10, Coinsurance condition: multiply the loss by carried insurance divided by required insurance (ratio capped at 1), subtract the deductible, floor at zero, then cap at the limit of insurance. An applicable margin cap may further limit payment. No loss-threshold shortcut applies. Last reviewed September 16, 2026.