ISO vs Ductulator
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
ISO
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ISO-5167 Orifice calculates size, flow-rate or pressure drop for gas and liquid flow orifice meters based on the International Standard Organization's ISO-5167. Orifice Size is calculated from given flow-rate and pressure drop, Flow-rate is calculated from given size and pressure drop and Pressure Drop requires orifice size and flow-rate. Different taps can be selected: Flange Taps, D and D/2 or Corner taps. Fluids include gases: Natural Gas (Specific Gravity must be provided), Air and Nitrogen, or liquids: Crude Oil, Water, Methanol, Mono-ethylene Glycol, Diethylene Glycol and Triethylene Glycol. In addition, selecting orifice material will adjust the sizing parameter of the orifice depending on temperature. Customary (US-units) or SI-units can be selected.
Ductulator
Instantly calculate HVAC duct sizes based on airflow, friction rate, or velocity. This tool provides accurate duct dimensions in seconds without needing charts, supporting various duct types and units.
- Instant duct sizing
- Friction rate or velocity calculation
- Multiple valid duct dimensions
- IP and SI units support
- Detailed sizing mode
- Rectangular, circular, and flexible ducts
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Size HVAC ducts instantly using airflow, friction or velocity. Get accurate duct dimensions in seconds — no charts required. • Get a range of suitable duct sizes based on friction rate or velocity. • Get multiple valid duct dimensions instantly. • Tap on Friction Rate or Velocity to toggle between calculation methods. • IP and SI units. • Detailed sizing mode to adjust the duct dimensions and air flow rates. • Supports rectangular, circular and flexible ducts. • Automatic friction and velocity updates. Calculations are based on standard air 0.075 lb/ft3 (1.2 kg/m3) in clean galvanized steel or non-metallic flexible ducts. Any feedback is welcome, and will be the basis for future updates.
Screenshots
Verdict
The clearest difference is update cadence: Ductulator at every 2 months against ISO's every 18 months. Ductulator also leads on chart position (#31 vs unranked). ISO's advantage is price ($0.99 vs $3.99) and iOS requirement (15.6 vs 18.6). On ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
ISO costs $0.99 and Ductulator $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.
ISO ships an update every 18 months, Ductulator every 2 months. The most recent releases landed on September 28, 2026 and October 26, 2026 respectively.
| Parameter | ISO | Ductulator |
|---|---|---|
| Price | $0.99 — better | $3.99 |
| Rating | — | 4.7 (353 ratings) — better |
| Positive reviews | — | 50.0% of reviews |
| Number of ratings | — | 353 — better |
| Update frequency | Every 18 months | Every 2 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | — | Free |
| Best chart rank | — | #31 — better |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 15.6 — better | 18.6 |
| Further details — not scored | ||
| Size | 1 MB | 1 MB |
| Age rating | 17+ | 4+ |
| Developer | Bjarne Berge | Wassim Murr |
Bugs and requests
ISO
Not enough reviews yet to summarise bugs or requests.
Ductulator
Reported bugs
4 issues- Decimal point doesn't work on calculator
- New flex option isn't working properly
- Friction rate can't be changed in the latest version
- Skips duct sizes (e.g., 24-26)
Requested features
5 requests- Ability to pick duct size and see CFM
- Include flat oval ducts
- Option to select round or square duct
- Ability to enter duct size and get CFM
- Option for flex duct
In-app purchases
ISO
No in-app purchases
Ductulator
No in-app purchases
