Engineer's Unit Converter vs HydroCalc
Price, ratings, monetisation and update history for both apps, side by side โ with what reviewers say about each.
Engineer's Unit Converter
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A unit converter built for engineering work rather than for the kitchen. Thirty-two categories, from the everyday ones to the specialist tables you normally go looking for in a handbook: AWG wire gauge, tons of refrigeration, viscosity, water hardness, radiation dose, moment of inertia. EVERY CATEGORY, ALL FREE Length, Area, Pressure/Stress, Mass/Weight, Energy/Work, Power, Force, Torque, Volume, Temperature, Time, Speed, Angle, Data, Frequency, Fuel Economy, Density, Flow, Viscosity, Acceleration, Electric Current, Voltage, Resistance, Electric Charge, Magnetic Flux Density, HVAC Cooling, Water Hardness, Radiation Activity, Radiation Dose, Radiation Equivalent Dose, Moment of Inertia, Wire Gauge. No unlocks, no ad to watch first, no timer. Every category above is open the moment you install. ENGINEERING TOOLS An expression calculator that accepts arithmetic, fractions and scientific notation, so you can type 3/8 or 1.2e-3 straight into the field. An HVAC sizing helper that turns tons of refrigeration into BTU/h, kW and rule-of-thumb airflow. Reference tables for physical constants, thermocouple types and hardness scales. BUILT FOR THE JOB Works fully offline, so it does not care about signal on site. Reads decimal commas and points the way your region writes them. Pin the units you use, hide the ones you never touch, and reorder the rest. Add your own units with a conversion factor. Every conversion is kept in a searchable history you can tap to reuse. No account, no sign-in, no data leaves the device.
HydroCalc
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HydroCalc is a calculation aid for heating and HVAC technicians. Calculate flow from heat output and temperature difference alongside the existing hydraulic calculators. CIRCUIT PROJECTS Create named projects and group circuits by room, category or floor. Record heat output, temperature difference and input sources for each circuit. View total heat output and required flow together. BASELINE AND COMPARISON Capture a fixed baseline and edit later proposals independently. Review differences in totals and share a calculation worksheet with inputs, sources and comparison. German and English. Local projects and calculations work offline. Existing purchase unlocks remain available. Professional calculation aid: manufacturer data, applicable rules, system design and actual measurements take precedence. Check results against the real installation. EULA: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is ads: HydroCalc at none against Engineer's Unit Converter's shown. Engineer's Unit Converter's advantage is update cadence (monthly vs every 2 months). On price, in-app purchases, device support and iOS requirement there is nothing between them.
Scored on Price ยท Rating ยท Positive reviews ยท Number of ratings ยท Update frequency ยท Ads ยท In-app purchases ยท Monetization ยท Best chart rank ยท Devices ยท Requires iOS
Both are free to download. Engineer's Unit Converter sells 1 one-off in-app purchase and HydroCalc sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
Engineer's Unit Converter ships an update monthly, HydroCalc every 2 months. The most recent releases landed on October 26, 2026 and October 25, 2026 respectively.
| Parameter | Engineer's Unit Converter | HydroCalc |
|---|---|---|
| Price | Free | Free |
| Update frequency | Monthly โ better | Every 2 months |
| Ads | Yes | No โ better |
| In-app purchases | Yes | Yes |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 18.0 | 17.0 โ better |
| Further details โ not scored | ||
| Size | 7 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | Jose Gerardo Palma Duran | Piotr Kaminski |
In-app purchases
Engineer's Unit Converter
- Remove Ads$0.99
HydroCalc
- HydroCalc Pro$3.99
Questions
Is Engineer's Unit Converter free?
Is HydroCalc free?
Do Engineer's Unit Converter or HydroCalc have ads?
Which is updated more often, Engineer's Unit Converter or HydroCalc?
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