O vs ISO
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
O
This app helps users calculate O-Ring dimensions and find compatible materials for their applications. It provides recommendations based on ISO standards and supports both metric and inch measurements.
- O-Ring housing calculation
- O-Ring size recommendations by ISO standard
- Quick search by national/international standards
- O-Ring tolerance calculation
- Metric and inch unit switching
- Chemical compatibility check
- Integration of Trelleborg Sealing Solutions Videos
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The Trelleborg Sealing Solutions O-Ring App calculates O-Ring dimensions by simply entering installation specifications for your application in metric or inch. In addition, the App recommends O-Ring sizes according to ISO 3601 so you know exactly which part you need. Features at a Glance: - O-Ring Housing: After entering the bore or rod/shaft diameter, you will receive an O-Ring recommendation and O-Ring housing calculation according to the recommendations of ISO 3601 - O-Ring Quick Search: offers the selection of O-Ring nominal sizes according to the following national/international standards: ISO 3601-1 Class B (International), ISO 3601-1 Class A (AS 568, USA), NFT 47-502 (France), JIS B 2401 (Japan) SMS 1586 (Sweden) - Tolerances: calculation of O-Ring tolerances according to ISO 3601-1 Class B and Class A - Switch between metric and inch - Chemical compatibility check: find out which materials are compatible with the media used in your application. - Integration of Trelleborg Sealing Solutions Videos
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.
Screenshots
Verdict
The clearest difference is price: O at Free against ISO's $0.99. O also leads on update cadence (every 3 months vs every 18 months) and iOS requirement (12.1 vs 15.6). 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
O is free to download; ISO costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.
O ships an update every 3 months, ISO every 18 months. The most recent releases landed on October 12, 2026 and September 28, 2026 respectively.
| Parameter | O | ISO |
|---|---|---|
| Price | Free — better | $0.99 |
| Rating | 3.8 (5 ratings) — better | — |
| Positive reviews | 83.3% of reviews | — |
| Number of ratings | 5 — better | — |
| Update frequency | Every 3 months — better | Every 18 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | — |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 12.1 — better | 15.6 |
| Further details — not scored | ||
| Size | 26 MB | 1 MB |
| Age rating | 12+ | 17+ |
| Developer | Trelleborg Sealing Solutions | Bjarne Berge |
In-app purchases
O
No in-app purchases
ISO
No in-app purchases
