# Attic Vent NFA Calculator — Roof & Exhaust Sizing Tool

> Roof & Exhaust Sizing Tool (iPhone/iPad app by Prashant Angyan.)

- Source: https://appshunter.io/ios/app/attic-vent-nfa-calculator/id6775809411 (this page in markdown: same URL + `.md`)
- Developer: [Prashant Angyan](https://appshunter.io/developer/1896613326)
- Category: Utilities, Business
- Price: $3.99
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: American English
- Released: 2026-06-04
- Data updated: 2026-07-19
- User reviews in markdown: https://appshunter.io/ios/app/attic-vent-nfa-calculator/id6775809411/reviews.md

## What is Attic Vent NFA Calculator?

You're on a roof, the inspector wants to know if you have enough vent area, and you need the number now. Not later, not after you find service to load a website.

Attic Vent NFA Calculator does the math for IRC Section R806.2. Enter your attic floor area, pick your code ratio (1:150 or 1:300) and intake/exhaust split (50/50 or 60/40), and get your answer.

WHAT YOU GET
- Total NFA (net free area) in square inches
- Intake NFA and exhaust NFA, split the way you chose
- How many standard soffit vents you need (based on 8x16 vents at 50 sq in each)
- How many linear feet of ridge vent you need (based on standard 18 sq in/ft)

QUICK REFERENCE A built-in reference card with three sections:
-NFA lookup table for common attic sizes (500 to 3,000 sq ft) at both ratios
-When to use 1:150 vs 1:300, including the climate zone conditions from IRC R806.2
- NFA ratings for 10 common vent types (ridge, soffit, gable, roof louver, turbine)

BUILT FOR CONTRACTORS
- Results are large, scannable numbers. No charts, no graphs, no clutter.
- Smart defaults on every field. Open the app, see a result, change one number.
- Works offline. No internet connection needed, ever.
- No account, no login, no tracking.
- Works with VoiceOver and Dynamic Type.
- No ads, no subscription.

$3.99, once. You own it.


## Version history (last 1 release)

### 1.0 — 2026-06-04

No release notes.

## More apps by Prashant Angyan

- [Fabric Yardage Calculator](https://appshunter.io/ios/app/fabric-yardage-calculator/id6775373995)
- [Paid: Invoice & Estimate Maker](https://appshunter.io/ios/app/paid-invoice-and-estimate-maker/id6779069100)
- [Tend: Keep in Touch & Notes](https://appshunter.io/ios/app/tend-keep-in-touch-and-notes/id6783643143)
- [PagePrep: PDF Margins & Notes](https://appshunter.io/ios/app/pageprep-pdf-margins-and-notes/id6785162996)

All apps by Prashant Angyan: https://appshunter.io/developer/1896613326

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-19.*