Thermocouple vs RTD
Which temperature sensor should you use? We cut through the jargon to help you decide between these two industrial standards.
Choosing between a thermocouple (TC) and an RTD (Resistance Temperature Detector) is one of the most common decisions people face when measuring temperature. Both are proven, industrial-grade technologies—but they perform differently, cost differently, and shine in different applications.
This guide explains how they work, key differences in accuracy and range, and exactly when you should choose one over the other.
Quick Comparison
| Feature | Thermocouple (TC) | RTD |
|---|---|---|
| How it works | Voltage from two metals | Resistance change in platinum |
| Typical Accuracy | Good (±1–2°C) | Excellent (±0.1–0.3°C) |
| Temperature Range | Very wide (-200°C to +2300°C) | Moderate (-200°C to +600°C) |
| Response Time | Fast | Moderate |
| Cost | Lower | Higher |
| Long-term Stability | Moderate | Excellent |
| Durability | Very rugged | More fragile |
Thermocouples
What is it?
A thermocouple is made from two dissimilar metals joined together at one end. When the junction is exposed to heat or cold, a tiny voltage is generated (Seebeck Effect).
When to Choose a Thermocouple
- Temperatures are above 600°C (1,100°F)
- Harsh, vibrating, dirty, or corrosive environments
- Fast response time is critical
- Lower cost is a primary factor
Typical Applications
Industrial ovens, furnaces, kilns, gas turbines, engines, exhaust stacks, metal processing.
RTDs
What is it?
An RTD (Resistance Temperature Detector) measures temperature by monitoring how the electrical resistance of a metal (usually platinum) changes with temperature.
When to Choose an RTD
- Accuracy is more important than extreme range
- Operating between -200°C and +600°C
- Need stable readings over long periods
- Regulatory compliance (FDA, pharma)
Typical Applications
Food processing, cold storage, pharmaceuticals, labs, HVAC, environmental monitoring.
Wiring Differences Matter
This trips people up constantly. You cannot swap them without changing wiring.
Thermocouples Require:
- Specific extension wire (Type K, J, etc.)
- Correct polarity (+/-)
- Cold-junction compensation
RTDs Use:
- Standard copper instrumentation wire
- 2, 3, or 4-wire configurations
- Lead-wire resistance compensation
The Bottom Line
Need help picking the right sensor?
The team at TIPTEMPerature Products can help you spec the right probe, wire, and hardware for your application.