# RTD Reference vs Units App

The clearest difference is rating: RTD Reference at 5.0 against Units App's 2.0. Units App's advantage is price ($0.99 vs $3.99). On ratings volume, update cadence, ads and in-app purchases there is nothing between them.

RTD Reference costs $3.99 and Units App $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

RTD Reference holds the better App Store score, 5.0 against 2.0. Both are backed by a comparable volume of ratings — 1 and 1 respectively.

RTD Reference ships an update every 8 months, Units App every 9 months. The most recent releases landed on September 25, 2026 and October 1, 2026 respectively.

## The numbers

| Metric | RTD Reference | Units App |
| --- | --- | --- |
| Price | $3.99 | **$0.99** |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/rtd-reference/id424267590/reviews)** | [2.0 (1 ratings)](https://appshunter.io/ios/app/units-app/id510085915/reviews) |
| Number of ratings | 1 | 1 |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 8 months** | Every 9 months |
| Monetization | Paid | Paid |
| Size | 5 MB | 2 MB |
| Requires iOS | 12.0 | 12.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Dohmann Engineering Services](https://appshunter.io/developer/401682475) | [Piet Jonas](https://appshunter.io/developer/288060167) |

## What reviewers say

### RTD Reference

[App page](https://appshunter.io/ios/app/rtd-reference/id424267590)

Instantly convert resistance to temperature and vice versa for over 70 RTD types and 9 popular thermistors. This tool uses precise algorithms for accurate calculations, ideal for field technicians and engineers.

**Highlights:** 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

**Features:** macOS Compatibility

**In-app purchases:** none


### Units App

[App page](https://appshunter.io/ios/app/units-app/id510085915)

Easily convert between various units across multiple categories including length, temperature, and weight. Access past conversions through a history list and send calculations via email. Supports a wide range of Apple devices.

**Highlights:** Multiple unit categories, Metric and imperial systems, Conversion history, Send calculations via email, iPad multitasking support

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is RTD Reference free?

RTD Reference costs $3.99, with no in-app purchases.

### Is Units App free?

Units App costs $0.99, with no in-app purchases.

### Which has better reviews, RTD Reference or Units App?

RTD Reference is rated higher. RTD Reference averages 5.0 out of 5 from 1 ratings, while Units App averages 2.0 from 1 ratings.

### Do RTD Reference or Units App have ads?

Neither RTD Reference nor Units App shows ads.

### Which is updated more often, RTD Reference or Units App?

RTD Reference ships an update every 8 months, and Units App every 9 months. Most recently, RTD Reference was updated on September 25, 2026 and Units App on October 1, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*