Flood Insurance Calculator
The risk, the cover and the years
Your result will appear here
Fill in the fields and this updates as you type.
Know what this estimate is based on
- Jurisdiction
- United States — insurance is regulated state by state, so the rules behind a premium are your state's, not a federal schedule
- Rules and time period
- Premiums, limits and deductibles are the figures you enter. Health plan cost-sharing caps, Medicare amounts and state filings all reset annually.
- Scope and limitations
- Educational estimate only. Rates, required coverages and available discounts differ by where you live. Your premium is set by an insurer's own underwriting — driving record, claims history, credit-based insurance score where permitted, the property itself — and only a quote is binding. What a policy pays depends on its exclusions and limits, not on this estimate.
- Source links checked
- Sep 19, 2026
Built and regression-tested by Smart Tools Lab. It has not been individually reviewed by a licensed financial, tax, or legal professional.
How to use
- 01
Enter the annual premium you have actually been quoted, from an agent writing NFIP business, a Write Your Own insurer, or a private flood carrier. The page will not invent one for you: since Risk Rating 2.0 the NFIP prices each building on its own flood frequency, the flood types that reach it, its distance to a water source, its elevation and what it would cost to rebuild, so no average premium says anything about your address.
- 02
Enter what a flood would actually do to the building. Think in feet of water rather than in total losses — flood damage scales with depth, and even a shallow flood takes out flooring, drywall, cabinetry, mechanical systems and everything stored at floor level. This is the figure the whole answer scales with, so it is worth getting from a contractor rather than from instinct.
- 03
Enter the chance of a flood in any single year. Inside a mapped Special Flood Hazard Area that figure is 1% by definition: 44 CFR 59.1 defines the base flood as the flood with a one percent chance of being equaled or exceeded in any given year, and defines the special hazard area as land subject to a 1 percent or greater chance of flooding annually. Outside one, enter something lower — and find out which you are in on the Flood Insurance Rate Map at FEMA's Map Service Center before guessing.
- 04
Enter how long you expect to own the place, then open Advanced options for the deductible and the policy limit. The deductible comes off every claim, and federal law sets minimums for NFIP policies — $1,000 or $1,250 for post-FIRM buildings depending on the coverage amount, $1,500 or $2,000 for pre-FIRM ones (42 U.S.C. 4019(b)). The limit is the ceiling on what the policy can pay, and an NFIP single-family dwelling cannot carry more than $250,000 of building coverage (44 CFR 61.6).
- 05
Read the expected loss per year, then set it against the premium, then read the chance of a flood over the whole time you will own the house. The one-year comparison will usually favor not buying, because a premium has to cover expenses as well as claims. The multi-year probability is the figure that decides the question, because it says how likely it is that you will be wrong once.
Formula
The policy's payout on a flood is max(0, min(the policy limit, the damage − the deductible)) — the deductible comes off first and the limit caps what is left, so a large enough loss is capped twice. The expected loss per year, which is the page's headline, is the annual flood chance × the full damage: it deliberately uses the whole loss rather than the covered part, because that is the risk sitting on you before any policy exists. The expected payout is the same chance × the payout, and it is what the premium should be compared against. Premiums over the years are simply the annual premium × the years you expect to own the place. The chance of at least one flood over that period is 1 − (1 − chance)^years, which treats each year as independent of the last — a simplification worth knowing about, since a changed watershed, upstream development or a wetter climate makes real flood years correlated rather than independent. The fair chance the page reports is the annual flood probability at which the premium would exactly equal the expected payout: premium ÷ payout × 100. Below it the premium is above the expected payout, which is the normal state of affairs for insurance and not evidence of a bad deal; above it the policy is priced under the risk you are carrying.
Example
A house would take about $55,000 of damage in a flood, the owner has been quoted $900 a year with a $2,000 deductible and a $250,000 limit, the property sits in a mapped 1%-a-year flood zone, and they expect to own it for 20 years. The expected loss is $550 a year against a $900 premium, and over the 20 years the premiums come to $18,000. The policy would pay $53,000 after the deductible, and the page puts the chance of at least one flood while they own the place at about 18%, noting that the premium would equal the expected payout at a flood chance of about 1.70% a year. Stretch the ownership to 30 years, the span of a standard mortgage, and the premiums rise to $27,000 while the chance of at least one flood rises to about 26%. Now the labeled alternates. Outside the mapped zone at a 0.2% annual chance, the expected loss falls to $110 a year and the 20-year flood chance to about 4% — the premium is buying much less, though the $55,000 has not gone anywhere. On a higher-risk property at 2% a year with $120,000 of damage, the expected loss is $2,400 against the same $900 premium, the chance over 20 years is about 33%, and the page reports the expected payout exceeding the premium: the policy is priced below the risk. Raising the deductible from $2,000 to $10,000 cuts the payout on the $55,000 flood from $53,000 to $45,000. And at $400,000 of damage the $250,000 limit binds: the policy pays $250,000, not $398,000.
Definitions
- Flood policy premium (yearly)
- What the policy costs for a year, from the NFIP through an agent or Write Your Own insurer, or from a private carrier. Priced per building under Risk Rating 2.0, so a neighbor's figure is not a guide to yours.
- Damage a flood would do
- What a realistic flood would cost to put right, in construction terms. Flood damage scales with depth, so this is a question about feet of water rather than about a total loss.
- Chance of a flood in any year
- The annual probability. Inside a Special Flood Hazard Area it is 1% by federal definition; outside one it is lower, but a map boundary is a line on a drawing rather than a wall, so it is never zero.
- Years you expect to own it
- How long you are carrying the risk. It does not change the one-year expected loss at all; it changes the probability that you meet the event at least once.
- Policy deductible
- What comes off every claim before the policy pays. Federal minimums apply to NFIP policies: $1,000 or $1,250 post-FIRM and $1,500 or $2,000 pre-FIRM, under 42 U.S.C. 4019(b).
- Policy limit
- The most the policy can pay for the building. The NFIP Regular Program caps a single-family dwelling at $250,000 of building coverage and $100,000 of contents, under 44 CFR 61.6.
- Expected loss per year
- The annual flood chance multiplied by the full damage — the average annual cost of the risk itself, before any policy. Deliberately not reduced by the deductible or the limit.
- Base flood
- The flood with a one percent chance of being equaled or exceeded in any given year, as defined at 44 CFR 59.1. The basis of the flood maps, the mandatory purchase rule and the 100-year label.
- Special Flood Hazard Area
- Land subject to a 1 percent or greater annual chance of flooding, shown on a Flood Insurance Rate Map. Inside one, a federally backed mortgage carries a flood insurance requirement.
- Risk Rating 2.0
- FEMA's current pricing methodology, which rates a building on flood frequency, flood type, distance to water, elevation and rebuild cost rather than principally on its map zone.
Frequently asked questions
Is flood insurance worth the premium?
Judged on one year's expected value, almost never; judged on the years you will own the house, frequently. On the defaults — a $900 premium, $55,000 of damage, a 1% annual flood chance, 20 years of ownership, a $2,000 deductible and a $250,000 limit — the expected loss is $550 a year against a $900 premium, and the premiums add up to $18,000 over the 20 years. The policy would pay $53,000 after the deductible. That looks like a bad trade until you read the last figure: there is about an 18% chance of at least one flood while you own the place, and the $55,000 arrives all at once.
What are the real odds of a 100-year flood?
One in a hundred every single year, not once a century, and the name is the most expensive piece of bad phrasing in American housing. The federal definition is explicit: 44 CFR 59.1 defines the base flood as the flood having a one percent chance of being equaled or exceeded in any given year. Stack that up and the arithmetic is uncomfortable. At 1% a year, the page puts the chance of at least one flood at about 18% over 20 years of ownership and about 26% over a 30-year mortgage. A one-in-four chance of a $55,000 bill is not a remote risk.
Does my homeowners policy cover flood?
No. Flood is excluded from every standard homeowners and renters policy sold in the United States, and it is excluded outright rather than sublimited, so without a separate policy the whole loss is yours — the full $55,000 on the defaults here. The exclusion catches people because a burst pipe is covered and rising water is not, and the difference is where the water came from rather than what it did. If water that reached your house was on the ground first, you are reading the wrong policy.
How much will an NFIP policy actually pay?
Up to $250,000 on the building and $100,000 on contents for a single-family dwelling under the Regular Program, which are the statutory maximums set out at 44 CFR 61.6 — and contents are a separate purchase, not something building coverage includes. The page shows the ceiling biting when the damage is large: run $400,000 of damage against the default $250,000 limit and the policy would pay $250,000 rather than $398,000, leaving $150,000 on you even after buying the largest NFIP policy available. A house worth more than that to rebuild needs either excess flood cover from a private carrier or an acknowledged shortfall.
Am I required to buy flood insurance?
If the building is in a Special Flood Hazard Area and the mortgage is federally regulated or federally backed, yes. Under 42 U.S.C. 4012a(b)(1), federal lending regulators must direct regulated lenders not to make, increase, extend or renew a loan secured by improved real estate in such an area unless the building is covered for the term of the loan, in an amount at least equal to the outstanding principal balance or the maximum NFIP limit available for that type of property, whichever is less. The same paragraph requires lenders to accept qualifying private flood insurance in satisfaction of that requirement. Outside a mapped high-risk zone nobody makes you buy it, and nothing about the requirement ending means the water stops at the zone boundary.
How does Risk Rating 2.0 decide my premium?
By rating the building rather than the zone. FEMA's own description of the methodology lists flood frequency, multiple flood types — river overflow, storm surge, coastal erosion and heavy rainfall — distance to a water source, and property characteristics including elevation and the cost to rebuild. That replaced an approach FEMA describes as predominantly static measurements emphasizing a property's elevation within a zone on a Flood Insurance Rate Map. The practical consequence is that two houses on the same street, in the same zone, can now be priced very differently, and that a neighbor's premium tells you almost nothing about yours.