How to use the dwelling coverage calculator
Enter your home’s living area and a local rebuild cost per square foot. This number is the key input, and the tool has no default for it. Get it from a local builder or contractor, or from your insurer’s replacement-cost estimate. Then add a percentage for features above standard, and the cost to rebuild detached structures.
A second worked example
What the result means
Compare the rebuild estimate with the dwelling limit on your declarations page. If your limit is well below the estimate, you may be underinsured, which means a total loss could cost more to rebuild than your policy pays.
| Value | Includes | Use it for |
|---|---|---|
| Rebuild (replacement) cost | Labor, materials and permits to rebuild the house | Setting Coverage A |
| Market value | House plus land, set by the housing market | Buying or selling, not insurance |
| Assessed value | Value set for property taxes | Taxes only |
| Coverage B (10% of A, typical) | Detached garage, fence, shed | Checking detached structures |
State and policy rules that change the answer
- Coverage B size. The California Department of Insurance says Coverage B is normally limited to 10% of Coverage A and can be increased for an extra premium (accessed October 2026).
- Extended or guaranteed replacement cost. These add-ons help when rebuild prices jump after a disaster. Ask whether your policy has one.
- Ordinance or law coverage helps pay to bring a rebuilt home up to current building codes.
- Excluded perils. Standard homeowners policies usually exclude flood and earthquake. Our flood and earthquake insurance guide explains separate coverage.
- Percentage deductibles. In many coastal states, hurricane or wind deductibles are a percentage of the dwelling limit, so a higher Coverage A also means a higher deductible. Our percentage deductible calculator shows the effect.
Common mistakes
- Using the purchase price. It includes land and market swings, not rebuild cost.
- Using a national average cost. Local labor and materials vary a lot.
- Forgetting remodels. A new kitchen or addition raises rebuild cost.
- Ignoring detached structures. A large garage or fence can exceed 10% of Coverage A.
Where this fits in your policy
Coverage A drives other parts of a homeowners policy, which often set personal property and loss of use as a share of it. Our homeowners insurance coverage guide explains Coverages A through F. If you rent instead of own, try our renters insurance calculator.
How the calculation works in plain words
The tool multiplies your living area by your local rebuild cost per square foot. If you entered a percentage for premium finishes, it raises that result by the same percentage, so 10% turns $400,000 into $440,000. That figure is the rebuild estimate, a starting point for your dwelling coverage limit.
Next, it takes 10% of the rebuild estimate. That is a typical other structures limit, because many policies set Coverage B at 10% of Coverage A. Finally, it compares that amount with what you said your detached structures would cost to rebuild. If they cost more, the difference is shown as the shortfall. If they cost less, the shortfall is $0.
Questions to ask your insurer or builder
- What replacement-cost estimate did you use for my home? Ask what square footage, building quality and features it assumes, and correct anything that is wrong.
- Does my policy include extended or guaranteed replacement cost? Ask how much extra it would pay above the limit.
- Does my dwelling limit adjust for inflation at renewal? Some policies raise it automatically.
- Can I raise Coverage B, and what would it cost? This matters if you have a large garage, barn or long fence.
- What would a local builder charge per square foot for a home like mine? Ask what is included, such as demolition, permits and site work.
Write the answers down and compare them with the tool’s estimate. If the numbers are far apart, ask why before your next renewal.
Where to find your numbers
Your living area is often listed on your appraisal, your property tax record or the listing from when you bought the home. Measure it yourself if you are unsure, counting only finished, heated space. For the cost per square foot, ask a local builder what it would cost to rebuild a home of your size, age and quality, including demolition and permits. Your insurer’s replacement-cost estimate is another reference point, and you can ask for a copy. For detached structures, ask for a rough price to rebuild each one, or use what you paid if it was recent. Your current dwelling and other structures limits are on your declarations page.
