How to size your dwelling coverage
Property policies size coverage on replacement cost — what it would take to rebuild the structure today, land excluded. Multiply the building area by a local rebuild cost per sq ft to get that figure, then apply the coinsurance percentage printed on your declarations page to find the limit you are expected to carry.
If your limit falls short of that required amount, a partial loss is paid in proportion: limit divided by required amount, then less the deductible. This calculator shows the required limit, any shortfall, the payment ratio and what you would absorb yourself.
Basis and date — the coinsurance condition appears in standard commercial and dwelling property forms such as ISO CP 00 10, and the percentage on your own declarations controls. Rebuild costs move with local labor and materials, so refresh them yearly. Content reflects September 2026.
This tool is an estimate only and does not determine what an insurer will pay. Ordinance or law coverage, debris removal, extended replacement cost endorsements and inflation guard all change the outcome, so review the actual policy with your agent.
Frequently asked questions
It asks you to carry a limit of at least 80% of the full replacement cost. Carry less and a partial loss is paid only in the proportion your limit bears to that required amount, after the deductible.
No. Payment can never exceed the policy limit, so a total loss is capped by the limit itself rather than reduced by the coinsurance ratio. The penalty bites hardest on partial losses.
No. Replacement cost is what it would take to rebuild the structure today, excluding land. Market value can be far higher or lower, which is why insuring to market value often leaves a coverage gap.