How we estimate — and where the numbers come from
No black boxes. Here’s exactly how every MoldCompass calculator turns your inputs into a cost range, what each rate is based on, and the limits you should keep in mind.
The core formula
Every cost calculator works the same transparent way professionals price these jobs: we take the affected area and multiply it by a per-square-foot rate, then add the flat costs that don’t scale with size — inspection, testing, containment, and drying equipment. That gives a headline total, and we show a low–high range around it (roughly −15% to +30%) because real jobs swing with access, materials, and how far the problem has spread.
Where the per-square-foot rates come from
The default rates are mid-range figures drawn from published 2025–2026 industry cost data (HomeGuide, HomeAdvisor, Today’s Homeowner and restoration-contractor pricing), cross-checked against the IICRC S500 water-damage and S520 mold-remediation standards that the industry actually follows. They’re editable on every calculator — if a contractor quotes you a different rate, type it in and the estimate updates.
Water damage categories (IICRC)
The biggest driver of a water-damage price is how contaminated the water is:
- Category 1 — clean water (a supply line, rain): lowest rate, roughly $3–$4 / sq ft.
- Category 2 — gray water (appliance overflow): roughly $4–$6.50 / sq ft.
- Category 3 — black water (sewage, flooding): the most expensive, $7–$12+ / sq ft, because porous materials it touched are removed and the area is sanitized rather than just dried.
What the estimates include — and don’t
Our totals cover the remediation or restoration work: removal, containment, cleaning, drying, and testing. They generally do not include fixing the underlying cause (a plumbing or roof repair), or full rebuild of finishes beyond what’s noted — those are separate line items a contractor will quote on site. We flag the big ones in each calculator’s “What changes the number.”
The insurance tools
Our claim and coverage tools follow standard US homeowners-policy logic: damage that is sudden and accidental from inside the home is typically covered; gradual leaks (a maintenance issue), outside flooding (which needs separate NFIP or private flood insurance), and sewer backups (which need a specific endorsement) generally are not. Mold follows the same rule and is often capped (commonly $1,000–$10,000). The “should I file?” tool then weighs your deductible plus the multi-year premium increase against paying out of pocket.
A ballpark, not a quote
These tools exist to give you a fair number before a contractor walks in — so you can spot a quote that’s out of line and decide whether to involve your insurer. They are estimates for planning, not bids, professional remediation advice, or coverage determinations. Always get an on-site inspection and confirm coverage with your insurer before you commit. See our disclaimer for the full terms.
Rates last reviewed: 2026. We revisit them as industry pricing shifts.