Home Insurance Calculator

The Home Insurance Calculator builds the coverage stack for a house from the one number everything hangs on, replacement cost, and shows whether your current dwelling coverage clears the minimum your policy's coinsurance clause quietly demands. Enter what the house would cost to rebuild, your net worth, and your current dwelling limit.

How It Works

Dwelling coverage is set to the full replacement cost. Personal property defaults to 50% of dwelling and loss of use to 20%, the standard industry ratios the calculator applies. Liability is set to the greater of $300,000 or your net worth, because liability exists to protect assets. The minimum dwelling coverage is 80% of replacement cost, and the coverage gap reported is how far your current limit falls below that floor.

$\text{Minimum dwelling coverage}=0.80\times\text{Replacement cost}$

Parameters

| Input | Required | Meaning | |---|---|---| | Replacement cost | Yes | Cost to rebuild the home as it stands | | Net worth | Yes | Drives the liability recommendation | | Current dwelling coverage | No | Enables the gap check against the 80% floor |

Worked example

A home costing $450,000 to rebuild: dwelling coverage$450,000, personal property $225,000, loss of use$90,000. With a net worth of $520,000 the liability recommendation is **$520,000** (the greater of the floor and net worth). If the current policy carries $320,000 of dwelling coverage, the minimum is$360,000 (80% of $450,000), so the calculator reports a **$40,000 coverage gap**: the home is underinsured past the point where the coinsurance penalty begins, not merely below full value.

Why the 80% floor matters more than the full value

Most homeowners policies contain a coinsurance or insurance-to-value clause: insure to at least 80% of replacement cost and partial losses are paid in full (less deductible); fall below it and partial losses are scaled down by the ratio of your coverage to the required 80%. A kitchen fire causing $100,000 of damage in the example above, insured at$320,000 against a $360,000 requirement, would be paid at roughly 320/360 of the loss, about$88,900, before the deductible, an $11,000 penalty for a gap the homeowner may never have been told existed. Total losses are capped at the limit either way, which is why the gap is a double exposure: scaled partial claims now, and a hard ceiling$130,000 below rebuild cost if the worst happens.

Replacement cost is not market value

The most consequential confusion in home insurance: market value includes land and location desirability; replacement cost is demolition plus rebuilding the structure at today's labour and materials prices. A house can be insured correctly at well below its sale price (expensive land, modest structure) or, in soft markets, above it (cheap land, costly construction). Estimates come from the insurer's replacement-cost estimator, a contractor's per-square-foot figure for your construction class, or an appraisal; whichever you use, finishes matter (custom kitchens and stone work rebuild at custom prices), and the figure should be revisited after renovations and every few years against construction inflation, which does not follow general inflation politely.

Liability and the ratios, tuned

The 50% and 20% ratios are defaults, not analysis: a household with significant valuables (jewellery, instruments, collections) needs scheduled coverage beyond the property figure, and loss of use should reflect local rents for a realistic rebuild timeline, which in tight markets means more than 20%. Liability at net worth is the floor of the reasoning, not the ceiling: future earnings are also attachable in many jurisdictions, which is why umbrella policies layered above the home policy's liability are the standard recommendation once net worth passes a few hundred thousand, and why the calculator takes the greater of $300,000 or net worth rather than ever recommending less.

Limitations

The calculator produces coverage targets from ratios, not a quote: premiums depend on location risks, construction, claims history, deductible, and insurer, none of which are inputs. It does not model flood or earthquake (separate policies, and standard policies exclude both), ordinance-and-law coverage for code upgrades, or guaranteed-replacement endorsements that change the ceiling arithmetic. Figures are planning targets for a conversation with your insurer or broker.

Frequently Asked Questions

Is insuring to 80% enough, then?

It avoids the coinsurance penalty on partial losses, but a total loss still caps at your limit: 80% cover on the example home leaves $90,000 of a full rebuild unpaid. The floor exists to prevent penalties, not to define adequate. Insuring to 100% of replacement cost is the defensible default.

Why is liability tied to net worth?

Because liability claims are paid from what you have. A judgment above your policy limit reaches your assets and, in many places, future income, so the limit should at least cover the balance sheet it is defending.

My insurer's replacement estimate differs from mine. What then?

Ask for the estimator's inputs (square footage, construction class, finishes) and correct them line by line; most disputes are input disputes. If the gap persists, an independent appraisal is the tiebreaker, and documenting it protects you at claim time.