4 vs TC
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
4
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.
- Two-way current to temperature conversion
- Custom min/max process range
- Support for negative temperatures
- Celsius and Fahrenheit support
- Fast and clean interface
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4-20 Temperature Calculator is a practical tool for engineers, technicians, and field service professionals working with 4-20 mA transmitters. Use it to quickly convert: • 4-20 mA to temperature • Temperature to 4-20 mA The app helps you work faster in the field by giving you a simple and accurate way to check transmitter scaling, verify loop values, and troubleshoot signal readings. Key features: • Two-way conversion between current and temperature • Custom min/max process range • Support for negative temperature ranges • Celsius and Fahrenheit input/output • Fast, clean interface for everyday use • Useful for HVAC, process control, maintenance, and commissioning work Whether you are calibrating a transmitter, checking a loop, or validating process values, 4-20 Temperature Calculator gives you the numbers you need in seconds.
TC
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.
- Thermocouple and RTD conversion
- Supports multiple sensor types
- Offline functionality
- Temperature recording and charting
- Export data to Excel
- Intuitive user interface
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This software is a user-friendly, efficient, and comprehensive tool designed for field technicians, engineers, and programmers. It allows for quick and easy conversion between resistance potential and temperature, suitable for various common temperature sensors. This application simplifies the temperature measurement process, providing a practical solution for professionals. Data support: Supports thermocouple types B, E, J, K, N, R, S, T, C, D, G with all voltages measured in millivolts (mV). The conversion formulas used are derived from NIST thermocouple tables and coefficients. Supports bi-directional query for PT1000, PT100, PT500, PT800, PT10, CU50, CU100, Ni100, Ni120, Ni1000 RTDs (ITS-90). Temperature recording: Supports temperature recording and temperature curve display, with one-click export of records and charts to Excel, facilitating on-site data entry and analysis. Fast and accurate: Instantly obtain the temperature coefficients and performance curves you need. Offline availability: Can be queried in field environments without network access. Intuitive interface: Clean design, easy to operate. Regular updates: Always maintains the latest industry standards. Whether you're an industrial automation engineer, process control expert, factory instrument engineer, or a student of temperature measurement, TC-RTD is an indispensable assistant for you.
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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 10, 2026 and September 15, 2026 respectively.
| Parameter | 4 | TC |
|---|---|---|
| Price | Free — better | $1.99 |
| Rating | 3.0 (2 ratings) | 5.0 (1 ratings) — better |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | 2 — better | 1 |
| Update frequency | Every 11 months | Every 3 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free — better | Paid |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.6 | 13.0 — better |
| Further details — not scored | ||
| Size | 30 MB | 12 MB |
| Age rating | 4+ | 4+ |
| Developer | Mantas Kamarauskas | 立娜 王 |
Customer experience
4
TC
In-app purchases
4
No in-app purchases
TC
No in-app purchases









