# HVAC Calculator & Ductulator — Duct Size, PT Chart, Superheat

> Duct Size, PT Chart, Superheat (iPhone/iPad app by Pairmind Limited.)

- Source: https://appshunter.io/ios/app/hvac-calculator-and-ductulator/id6805056342 (this page in markdown: same URL + `.md`)
- Developer: [Pairmind Limited](https://appshunter.io/developer/6792512625)
- Category: Utilities, Productivity
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 17.0 · 18 MB
- Languages: American English
- Released: 2026-09-07
- Data updated: 2026-10-15

## What is HVAC Calculator & Ductulator?

Size a duct from CFM and friction rate, or find the airflow capacity of an existing round duct. The ductulator works offline and opens directly when you launch the app; your first 5 duct sizings are free. No account required.

HVAC Calculator & Ductulator also includes refrigerant charge calculations, unit conversions, and Pro tools for airflow, load estimates, and PDF job reports.

DUCT SIZING (DUCTULATOR)
Enter CFM and friction rate to get round and rectangular duct sizes, with velocity limits checked for supply, return, and branch runs. Reverse mode calculates the max CFM of an existing duct. Sheet metal and flex are both supported.

REFRIGERANT CHARGE
Superheat and subcooling from gauge pressure and line temperature, compared against a target. R-410A is free; Pro adds R-32, R-454B, R-22, R-134a, and R-407C. Blends are handled correctly — dew line for superheat, bubble line for subcooling. PT values are computed from NIST reference equations, so you can enter any pressure instead of rounding to a chart's 25-psi steps. Target superheat for fixed-orifice systems is included (indoor wet bulb + outdoor dry bulb).

AIRFLOW
Temperature-rise CFM, the three fan laws, and CFM per ton with the 350–450 range built in — confirm airflow before adjusting the charge.

LOAD & CONVERSIONS
Quick BTU and tonnage estimates by climate zone (a clearly labeled rule of thumb, not a Manual J), plus BTU, kW, tons, CFM, L/s, PSI, kPa, °F and °C conversions.

JOBS & PDF REPORTS (PRO)
Save calculations to named jobs and export a PDF service report with your name and company on it — ready to hand over with the invoice.

FREE AND PRO
R-410A charge and unit conversions are free, and the ductulator is free for your first 5 uses. Pro unlocks unlimited duct sizing and adds the other five refrigerants, the full PT chart, airflow checks, load estimates, and PDF job reports. Pro requires a purchase. Available plans and local prices are shown in the app before you buy.

Questions, or a number that looks off? Email hello@pairmind.dev — every calculator is verified against published reference data.

For trained technicians. Verify results against manufacturer specifications. Load estimates are not a substitute for ACCA Manual J/D/S.

Privacy Policy: https://pairmind.dev/apps/hvac-calculator/privacy
Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| Pro Yearly | $19.99 | per year |
| Pro Monthly | $2.99 | per month |

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Pro Lifetime | $49.99 | one-time |


## Is HVAC Calculator & Ductulator safe?

Not enough ratings yet to assess HVAC Calculator & Ductulator.

## Is HVAC Calculator & Ductulator legit?

HVAC Calculator & Ductulator appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for HVAC Calculator & Ductulator is 65 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 5 releases)

### 1.0.5 — 2026-09-24

Pro is now a single one-time purchase — no subscription. The ductulator includes 5 free sizings; Pro unlocks unlimited use plus every other tool. Small fixes.

### 1.0.4 — 2026-09-21

Simpler Pro pricing: one lifetime purchase, or a monthly plan with a 7-day free trial. Spanish App Store listing for Spanish-speaking techs. Small fixes.

### 1.0.3 — 2026-09-13

Clearer information about free and Pro tools.

### 1.0.2 — 2026-09-11

Pro refrigerants now have clear badges and an explanation with Unlock Pro and Continue options. Your current refrigerant and measurements stay intact. Clearer Airflow and Load examples, plus improved review prompt timing.

### 1.0.1 — 2026-09-09

Open straight into the free duct calculator, with the tour available in Settings. Discover Pro after trying a calculation, or whenever you choose a paid feature. Includes improvements to purchase and paywall measurement.

## Apps similar to HVAC Calculator & Ductulator

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [Duct Calculator: HVAC Sizing](https://appshunter.io/ios/app/duct-calculator-hvac-sizing/id6789039757) | — | Free | Utilities |
| [HVAC Calculator - FieldCalc](https://appshunter.io/ios/app/hvac-calculator-fieldcalc/id6784082740) | — | Free | Utilities |
| [DuctPro: Duct Size Calculator](https://appshunter.io/ios/app/ductpro-duct-size-calculator/id6790157130) | — | Free | Utilities |
| [Static Pressure & Duct Check](https://appshunter.io/ios/app/static-pressure-and-duct-check/id6786886923) | 5.0 (1) | Free | Utilities |
| [BaseCalc HVAC Calculator](https://appshunter.io/ios/app/basecalc-hvac-calculator/id6786116451) | 5.0 (1) | Free | Utilities |
| [BO HOUSE MANAGEMENT](https://appshunter.io/ios/app/bo-house-management/id6452048450) | — | Free | Utilities |

## More apps by Pairmind Limited

- [RepsRoulette: App Blocker](https://appshunter.io/ios/app/repsroulette-app-blocker/id6792512623)
- [Tagwise – NFC Tools & Scanner](https://appshunter.io/ios/app/tagwise-nfc-tools-and-scanner/id6816677801)

All apps by Pairmind Limited: https://appshunter.io/developer/6792512625

## Related topics

[pt ductulator](https://appshunter.io/ios/topics/pt-ductulator) · [hvac calculator](https://appshunter.io/ios/topics/hvac-calculator)

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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 2026-10-15.*