Negative-air / scrubber sizing
Air changes per hour.
Mold · Calculator
Free · no login
Product overview
Size the air scrubbers for a mold containment. Enter room length, width, and ceiling height, set your target air changes per hour and the CFM rating of the units you run, and get the number of scrubbers the space needs. It's the check adjusters and remediators reach for when a scope calls for negative air — confirming the equipment count matches the room volume before it goes on the estimate or into the remediation plan.
The calculator works from room volume and target air changes per hour. Volume is length × width × height in cubic feet. Required airflow is volume × ACH ÷ 60 — that converts air changes per hour into cubic feet per minute. The scrubber count is the required CFM divided by each unit's rated capacity, rounded up so the space always meets the target. The default of 4 ACH is a common containment baseline; raise it for higher-hazard work. Rate units at their HEPA-filtered CFM, not the free-air spec. Verify against IICRC S520 and equipment ratings.
Product details
- Sold by
- Mensuria
- Product category
- Free field tool · Calculator
- Delivery method
- Web app · no login
- Cost
- Free
Highlights
- Deterministic — the same inputs give the same result, every time.
- Built for the trade, sized to feed Xactimate line-item quantities.
- Free — no login, no card.
- Works from a phone at the loss.
Vendor insights
Mensuria writes a neutral scope built to survive review — every line item sourced to a photo, anything unprovable held back and flagged for you. It never files the estimate; a licensed adjuster confirms every line and stays the adjuster of record. Mensuria is independent and not affiliated with Verisk or Xactimate; “Xactimate-ready” means the worksheet is organized for Quick Entry.
Pricing
This tool is free — no login, no card. The full scope-drafting product is priced below; your first claim is free.
Details
Delivery method
Mensuria is a web app — nothing to install. You work a claim in the browser and export a room-grouped, Xactimate-ready worksheet (codes, quantities, descriptions) organized for Quick Entry. There is no native .ESX import; you key the reviewed line items into Xactimate and stay in control.
Terms and conditions
Use of Mensuria is subject to our Terms of Service. Your first claim is free with no card; paid plans are billed monthly and cancel anytime.
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Support
Support
Reach the team at support@mensuria.com . You will hear back from people who have written a scope, not a ticket queue.
Onboarding
Your first claim walks you through capture, draft, review, and export step by step, so you are productive on claim one — no training required.
Refund policy
Monthly plans cancel anytime; the CAT Season Pass is a one-time add-on with no commitment.
Common questions
Figure the room volume (length × width × height), multiply by your target air changes per hour, and divide by 60 to get required CFM. Divide that by the filtered CFM of each unit and round up. For example, a 12 × 10 × 8 room is 960 CF; at 4 ACH that's 64 CFM required, so a single 500-CFM scrubber covers it. Larger rooms or higher ACH targets push the count up. This tool runs the math and rounds up so you never under-size the containment.
ACH — air changes per hour — is how many times the equipment cycles the full room volume in an hour. Four ACH is a widely used baseline for a mold containment under IICRC S520, and many remediators run higher for aggressive removal or elevated spore counts. Set the target to match your remediation plan, then let the calculator size the scrubbers. Document the ACH you used so the equipment line items on the estimate tie back to a stated design.
CFM = room volume × ACH ÷ 60. Volume is in cubic feet, ACH is your target changes per hour, and dividing by 60 turns an hourly figure into cubic feet per minute — the rating equipment is sold on. So a 1,000 CF room at 4 ACH needs 1,000 × 4 ÷ 60 ≈ 67 CFM of filtered airflow. This is the same formula the calculator uses; it just also divides by your unit CFM and rounds up to give you a whole scrubber count.
Use the filtered CFM — the airflow with the HEPA and any pre-filters installed, which is what the unit actually moves in a containment. Free-air ratings are higher and will make you under-size the equipment. Loaded filters drop output further over a job, so sizing to the filtered spec builds in a small margin. Enter the realistic filtered capacity of the units you're deploying, and the count will reflect what the room really needs.
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