# RTD Reference — RTD & Thermistor Conversion

> RTD and thermistor resistance to temperature conversion tool. (iPhone/iPad app by Dohmann Engineering Services.)

- Source: https://appshunter.io/ios/app/rtd-reference/id424267590 (this page in markdown: same URL + `.md`)
- Developer: [Dohmann Engineering Services](https://appshunter.io/developer/401682475)
- Category: Reference, Utilities
- Price: $3.99
- Rating: 5.00/5 from 1 App Store ratings · 2 written reviews indexed
- Age rating: 4+
- Requires: iOS 12.0 · 5 MB
- Languages: American English
- Released: 2011-03-12
- Data updated: 2026-08-16
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/rtd-reference/id424267590/reviews.md

## What is RTD Reference?

This application is a simple, fast, and comprehensive tool for field technicians, engineers and programmers to quickly and easily convert resistance to temperature and vice versa for many popular temperature sensing devices.

It includes support for over 70 types of RTDs (Resistance Temperature Detectors) and 9 types of popular Thermistors (Thermal Resistors).  These devices exhibit predictable changes in their resistance depending on their ambient temperature, a characteristic that makes them useful for measuring temperature in many residential, commercial and industrial applications.

Merely select your entry mode (resistance in ohms or temperature in deg F or C) and your RTD or Thermistor type. Your entries are converted to the other two units instantly as you type.

The app supports:
Platinum RTDs – 56 combinations of reference resistance and alphas
Copper RTDs - 4 combinations of reference resistance and alphas
Nickel RTDs - 8 combinations of reference resistance and alphas
Nickel-Iron RTDs (Balco) - 6 combinations of reference resistance and alphas
Thermistors – 9 popular types including two types of 10K thermistors

Although the behavior of RTDs and Thermistors is predictable, they are not linear. This app uses the Steinhart-Hart formula for Thermistor calculations, the Callendar-Van Dusen formula for Platinum RTDs and similar algorithms for the other types of RTDs. All formulas and coefficients used by the app are described in the documentation provided with the app.

A number of lookup charts are included showing resistance vs temperature for many of the most popular types of RTDs.

The app uses 64-bit double precision math to provide the best possible resolution and accuracy for its calculations. However, since the algorithms are curve-fitting approximations, there will certainly be some points at which there are very small (usually insignificant) differences between the calculated values and a manufacturer’s published data table.

You can use the Settings application to change background and text colors, change keyclick sounds, and adjust keyclick volume.

Please send any comments, suggestions or corrections to support@dohmann.com

## Key features

- Resistance to temperature conversion
- Temperature to resistance conversion
- Support for 70+ RTD types
- Support for 9 popular thermistor types
- Uses Steinhart-Hart and Callendar-Van Dusen formulas
- Accurate 64-bit double precision math
- Customizable display colors and sounds

## Chart rankings

- #191 in Top Paid · Reference (US App Store)

## Recent user reviews (2 of 2)

All indexed reviews: https://appshunter.io/ios/app/rtd-reference/id424267590/reviews.md

### 5/5 — RTD References

*2014-04-25*

Thanks!
Nice ang useful application.

### 1/5 — Mark

*2013-09-10*

Shocking does not work on iPad mini at all - cannot access keypad

So disappointing

## Frequently asked questions about RTD Reference

### What is RTD Reference?

RTD Reference is a utility application designed for converting resistance values to temperature and vice versa for various RTD and thermistor types. It employs precise mathematical formulas for accurate calculations.

### How many RTD and thermistor types does RTD Reference support?

RTD Reference supports over 70 types of RTDs, including Platinum, Copper, Nickel, and Nickel-Iron RTDs, as well as 9 popular types of thermistors.

### What formulas does RTD Reference use for calculations?

The application utilizes the Steinhart-Hart formula for thermistors and the Callendar-Van Dusen formula for Platinum RTDs, along with similar algorithms for other RTD types to ensure accuracy.

### What is the accuracy of RTD Reference calculations?

RTD Reference uses 64-bit double precision math for high resolution and accuracy. While algorithms are curve-fitting approximations, differences from manufacturer data tables are usually insignificant.

### Can I customize the appearance of RTD Reference?

Yes, you can change background and text colors, as well as adjust keyclick sounds and volume through the app's settings.

### What devices is RTD Reference compatible with?

RTD Reference is compatible with iPhone, iPad, and iPod devices. It has an age rating of 4+.

### How often is RTD Reference updated?

The latest version of RTD Reference is 1.06, which was last updated on July 6, 2021. The app was initially released on March 12, 2011.

### Does RTD Reference have ads?

No, RTD Reference is ad-free. It is a paid application available for $3.99.

## Version history (last 5 releases)

### 1.06 — 2021-07-06

•Reworked the overall UI for better presentation consistency across devices
•All views now support both portrait and landscape orientation
•Added more info and options to the documents view
•Added the ability to change text colors on the main view

### 1.05 — 2021-01-30

Added support for iOS 12.0 - 14
Dropped support for iOS versions older than 120
Several UI improvements

### 1.04 — 2014-03-22

UI improvements for iOS7 compatibility
Added support for 15KΩ thermistors

### 1.03 — 2013-07-11

User can now select a "favorite" RTD Chart from a list of Resistance vs Temperature charts. Just swipe left anywhere across the main RTD Reference display to bring up the list of available charts.

The app also supports emailing and printing the current favorite chart or the app documentation. Printing is done via AirPrint and requires connectivity to an Airprint-enabled printer or a computer running an Airprint simulator.

### 1.02 — 2012-11-21

The app is now a universal app with retina support for iPad and iPhone and full screen support for iPhone 5.

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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 2026-08-16.*