Comparison

O vs Hydraulic

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • 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
Features
Read full description

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

About

Hydraulic

Perform essential hydraulic calculations for cylinders, pumps, and fluid lines. Solve for forces, speeds, torque, power, and pressure drop. Supports metric and imperial units, with advanced features unlocked via in-app purchase.

Highlights
  • Cylinder force and speed calculations
  • Pump displacement, flow, and pressure calculations
  • Hydraulic line fluid velocity and pressure drop
  • Orifice flow and pressure calculations
  • Speed, torque, and power calculations
  • Metric and imperial unit support
  • Copy results to clipboard
Features
Read full description

The Hydraulic Calculator includes many basic hydraulic calculations. Cylinder calculations can be done to solve for extension / retraction forces or speeds. Pump calculations can also be done by entering combinations of displacement, oil flow and pressure to determine values for speed, torque and power. Both mechanical and volumetric efficiencies can be used in these calculations. Hydraulic line calculations can also be done for fluid velocity, cross sectional area, Reynolds number and pressure drop. The free version is limited to 1” or 25mm line diameters. Orifice calculations can also be made using three parameters: Oil Flow, Orifice Diameter and Pressure Drop. Enter any two values and have the third calculated. Speed - Torque - Power page: Enter any two values have the third calculated. Unit conversions built into the page. Calculations can be done in either metric or imperial units. Basic unit conversions are also available. With the in-app purchase, all features from the Hydraulic Calculator will become active: Cylinder characteristics can be entered in a number of different ways. Enter hydraulic flow, cylinder velocity, or stroke time and calculate the other two. User can also enter Hydraulic pressure, extend force or retract force and have the other two calculated. One application for this is to measure the stroke time of a cylinder. By entering this with the bore diameter and stroke length, the system flow is calculated. Full motor & pump calculation page. The motor & pump calculator are flexible tools in which the user can enter any three known values to have the remaining values calculated. Values include: displacement, oil flow, pressure, rotational speed, torque, and motor power. Both mechanical and volumetric efficiency values are used. Results can be copied to the clipboard in a text format for use in e-mails, messages, or other documentation.

Screenshots

O4 screens
Hydraulic4 screens

Verdict

The call

The clearest difference is in-app purchases: O at none against Hydraulic's 2. O also leads on review sentiment (83% vs 50%) and iOS requirement (12.1 vs 15.1). Hydraulic's advantage is rating (4.1 vs 3.8) and ratings volume (17 vs 5). On price, update cadence, ads 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Hydraulic sells 2 one-off in-app purchases. O asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Hydraulic holds the better App Store score, 4.1 against 3.8. Both are backed by a comparable volume of ratings — 5 and 17 respectively. Written reviews complicate that: 83% of O's written reviews are positive against 50% of Hydraulic's, so the app with the better star average is not the one people write more warmly about.

UpkeepUpdate frequency

O ships an update every 3 months, Hydraulic every 6 weeks. The most recent releases landed on October 12, 2026 and October 20, 2026 respectively.

Scorecard6 real differences · 4 level
O versus Hydraulic: the parameters behind the verdict, then further details
ParameterOHydraulic
PriceFreeFree
Rating3.8 (5 ratings)4.1 (17 ratings) — better
Positive reviews83.3% of reviews — better50.0% of reviews
Number of ratings517 — better
Update frequencyEvery 3 monthsEvery 6 weeks — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS12.1 — better15.1
Further details — not scored
Size26 MB24 MB
Age rating12+4+
DeveloperTrelleborg Sealing SolutionsZanthic Automation Inc.

Customer experience

O

All ratings5 ratings
Positive60.0%
Neutral20.0%
Negative20.0%
Written reviews12 reviews
Positive83.3%
Neutral0.0%
Negative16.7%

Hydraulic

All ratings16 ratings
Positive81.3%
Neutral12.5%
Negative6.3%
Written reviews8 reviews
Positive50.0%
Neutral0.0%
Negative50.0%

In-app purchases

None

O

No in-app purchases

2 purchases

Hydraulic

One-time2
  • Full Version$7.99
  • Pro Version$7.99

Questions

Is O free?
O is free to download, with no in-app purchases.
Is Hydraulic free?
Hydraulic is free to download, with in-app purchases available.
Which has better reviews, O or Hydraulic?
Hydraulic is rated higher. O averages 3.8 out of 5 from 5 ratings, while Hydraulic averages 4.1 from 17 ratings.
Do O or Hydraulic have ads?
Neither O nor Hydraulic shows ads.
Which is updated more often, O or Hydraulic?
O ships an update every 3 months, and Hydraulic every 6 weeks. Most recently, O was updated on October 12, 2026 and Hydraulic on October 20, 2026.

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