Homeowners Insurance Estimator
Size the dwelling limit from rebuild cost rather than sale price, then see how the deductible, roof age, and home age move the premium — and where the policy stops covering you at all.
Homeowners insurance premium model
Coverage tracks the rebuild, not the sale price
Dwelling coverage answers one question: what would it cost, at today's local prices, to put this house back exactly as it is. That number has almost nothing to do with what the house would sell for, because sale price bundles in the land, the location, and the local market's mood.
The error runs in both directions, which is why it is dangerous. In a coastal metro where land is most of the value, owners insure for far more than the structure is worth and overpay in premium for coverage the insurer will never pay. In a rural county where land is cheap but hauling materials is expensive, owners insure for the sale price and end up underinsured by tens of thousands of dollars.
The reliable method is area times local rebuild cost per square foot, then adjusted upward for custom finishes, and checked against a carrier's own replacement cost estimator — most will run one for free before binding a policy.
The 80% line, and what happens below it
Nearly every replacement cost policy carries a coinsurance clause requiring the dwelling limit to equal at least 80% of full rebuild cost. Exceed that threshold in the wrong direction and a partial loss is not paid in full — it is paid in proportion to how underinsured you were.
The arithmetic is unforgiving. A $370,000 rebuild with a limit of $240,000 is 65% insured against the required 80%, a ratio of 0.81. A $60,000 claim therefore pays about $48,600 rather than $60,000, and the owner absorbs the rest. The premium saving from carrying the lower limit is usually a few hundred dollars a year; the shortfall in a single claim can exceed a decade of those savings.
Many policies also include an extended replacement cost endorsement, which allows the payout to exceed the stated limit by 125% or 150% after a widespread event drives up local labour and material prices. That endorsement is worth its cost in exactly the scenario that produces large claims.
What a standard policy does not cover
The exclusions cause more financial damage than any pricing question, because they are invisible until a loss.
| Excluded by default | Where it comes from |
|---|---|
| Flood, storm surge, surface water | Separate NFIP or private flood policy |
| Earthquake, earth movement | Separate policy or endorsement |
| Sewer or drain backup | Low-cost water backup endorsement |
| Mold beyond a small sub-limit | Limited endorsement, if any |
| Gradual wear, rot, pest damage | Not insurable by design |
| Business use of the home | Separate commercial policy |
Flood deserves its own sentence. Roughly a quarter of federal flood claims come from outside the mapped high-risk zones, which means "I am not in a flood zone" is not the same statement as "I do not need flood coverage." A standard policy will pay nothing for water that came from outside the building, and no amount of arguing about the pipe that failed changes that classification.
The deductible is the honest lever
Insurance is priced so that small claims cost the carrier more to administer than they pay out, which is why the first few thousand dollars of deductible are cheap to remove and expensive to keep. Moving from $1,000 to $2,500 typically cuts the premium by around 10% to 12%. Moving from $2,500 to $5,000 saves proportionally less, because the insurer has already priced out most of the claims that step would eliminate.
The rule that makes this safe: never choose a deductible you could not pay in cash the same month as a loss. A deductible is not a discount, it is a self-insurance layer, and a household without the reserve has simply bought a policy that will fail at the moment it is needed.
Why the roof drives the price
In most markets the roof is the single most frequent source of large claims, and a roof near the end of its service life is not a risk but a scheduled event. Carriers price accordingly, and increasingly they change the terms rather than the rate: a roof past a certain age may be settled at actual cash value instead of replacement cost, which means a fifteen-year-old shingle roof pays out as a fifteen-year-old roof.
That shift matters more than the premium. An owner comparing quotes on price alone can miss that one policy pays replacement cost on a roof and another pays depreciated value, a difference that can exceed the entire annual premium in a single hail event.
What is not worth buying
Three add-ons are commonly oversold. Home warranty products bundled with a policy are service contracts with claim caps and exclusion lists, not insurance. Low-value electronics riders duplicate coverage already present under personal property. And "no-claim" discounts that vanish after one claim are priced into the base rate rather than granted.
What is usually worth buying: water backup, extended replacement cost, and — in any area with meaningful flood exposure — a separate flood policy. Those three cover the losses that actually bankrupt owners.
Frequently asked questions
Should coverage match my home's market value?
No. Coverage should match rebuild cost at current local prices. Market value includes land, which is not insured, so using it as the coverage figure distorts the limit in both directions.
What is the 80% coinsurance rule?
Most replacement cost policies require the dwelling limit to be at least 80% of full rebuild cost. Below that, a partial loss is paid in proportion to the shortfall — a $60,000 claim on a policy at 65% of required coverage pays roughly $48,600.
Does homeowners insurance cover flooding?
No. Flood is excluded from standard HO-3 policies and needs a separate NFIP or private policy. Water entering from outside the building is flood; water from a burst pipe inside is not.
How much does raising the deductible save?
About 10% to 12% going from $1,000 to $2,500, and less for the next step up. Only take a higher deductible if you could pay it in cash immediately after a loss.
Why does roof age matter so much?
Roof claims are the most frequent large claim in most markets. Past a certain age many carriers settle the roof at actual cash value rather than replacement cost, which cuts the payout to depreciated value.
What is the difference between ACV and replacement cost?
Actual cash value pays the depreciated value of what was lost. Replacement cost pays for a new equivalent without deducting depreciation. Dwelling coverage is usually replacement cost; personal property often is not.
Is sewer backup covered?
Usually not by default. Water backup is a cheap endorsement and a common, expensive loss, which makes it one of the few add-ons nearly everyone should carry.
Disclaimer: This is a pricing model, not a quote and not insurance advice. Premiums are set by individual carriers using territory, credit history, claims history, construction type, and protection class, none of which this tool can see. The state factors are relative risk indices, not filed rates. Obtain actual quotes before making a coverage decision.
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