# 4 vs TC

The clearest difference is price: 4 at Free against TC's $1.99. TC's advantage is rating (5.0 vs 3.0) and update cadence (every 3 months vs every 11 months). On ratings volume, ads, in-app purchases and device support there is nothing between them.

4 is free to download; TC costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

TC holds the better App Store score, 5.0 against 3.0. Both are backed by a comparable volume of ratings — 2 and 1 respectively.

4 ships an update every 11 months, TC every 3 months. The most recent releases landed on September 29, 2026 and October 27, 2026 respectively.

## The numbers

| Metric | 4 | TC |
| --- | --- | --- |
| Price | **Free** | $1.99 |
| Rating | [3.0 (2 ratings)](https://appshunter.io/ios/app/4-20-temperature-calculator/id1602351736/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/tc-rtd-reference/id6504454500/reviews)** |
| Number of ratings | **2** | 1 |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 11 months | **Every 3 months** |
| Monetization | **Free** | Paid |
| Size | 30 MB | 12 MB |
| Requires iOS | 15.6 | **13.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Mantas Kamarauskas](https://appshunter.io/developer/975306268) | [立娜 王](https://appshunter.io/developer/1761096632) |

## What reviewers say

### 4

[App page](https://appshunter.io/ios/app/4-20-temperature-calculator/id1602351736)

This utility app converts between 4-20 mA current signals and temperature readings. It's designed for engineers and technicians to quickly check transmitter scaling, verify loop values, and troubleshoot signal issues in various industrial applications.

**Highlights:** Two-way current to temperature conversion, Custom min/max process range, Support for negative temperatures, Celsius and Fahrenheit support, Fast and clean interface

**Features:** macOS Compatibility

**In-app purchases:** none


### TC

[App page](https://appshunter.io/ios/app/tc-rtd-reference/id6504454500)

This utility app provides quick and accurate conversions between resistance, potential, and temperature for various thermocouples and RTDs. It supports offline use, temperature recording with export, and offers an intuitive interface for field technicians and engineers.

**Highlights:** Thermocouple and RTD conversion, Supports multiple sensor types, Offline functionality, Temperature recording and charting, Export data to Excel, Intuitive user interface

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is 4 free?

4 is free to download, with no in-app purchases.

### Is TC free?

TC costs $1.99, with no in-app purchases.

### Which has better reviews, 4 or TC?

TC is rated higher. 4 averages 3.0 out of 5 from 2 ratings, while TC averages 5.0 from 1 ratings.

### Do 4 or TC have ads?

Neither 4 nor TC shows ads.

### Which is updated more often, 4 or TC?

4 ships an update every 11 months, and TC every 3 months. Most recently, 4 was updated on September 29, 2026 and TC on October 27, 2026.

---

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