Calculate RTD
Need a quick and reliable way to convert RTD resistance into temperature values? Our RTD temperature calculator helps you determine accurate temperature readings for platinum resistance sensors such as Pt100, Pt500, and Pt1000.
While calculators are convenient, some engineers and technicians prefer understanding the math behind the measurement. Below, you’ll not only find an easy-to-use RTD conversion tool, but also a breakdown of the core formulas used to translate resistance into temperature.
RTD Resistance to Temperature Calculator
This RTD calculator works with multiple platinum sensor types and converts resistance values (ohms) into temperature readings (°C) with high precision.
How to use the calculator:
- Input the RTD resistance value (based on a reference resistance at 0°C).
- Enter the known or target temperature in degrees Celsius.
- View the calculated RTD resistance or temperature coefficient instantly.
Why RTD Temperature Conversion Matters
A Resistance Temperature Detector (RTD) is widely used where precise and repeatable temperature measurements are required. High-quality RTDs can achieve accuracy within ±0.1°C, making them ideal for demanding applications.
Temperature control plays a critical role across industrial automation, healthcare, HVAC systems, and manufacturing processes. Even small temperature variations can affect system efficiency, safety, and product quality.
Although thermocouples and thermistors are also used for temperature sensing, RTDs are known for superior stability and accuracy over a wide operating range. By converting RTD resistance values into temperature readings, you can verify sensor output and ensure system reliability.
RTDs use platinum elements whose electrical resistance increases predictably as temperature rises. This consistent behavior allows accurate temperature calculation when the resistance is known.
Most RTD calculations are referenced to 0°C. Common platinum RTD types include:
- Pt100 – 100 Ω at 0°C
- Pt500 – 500 Ω at 0°C
- Pt1000 – 1000 Ω at 0°C
Next, let’s review how resistance values are converted into temperature.
RTD Resistance to Temperature Formula
The relationship between resistance and temperature for an RTD can be expressed using the following equation:
Rt = Rref × [1 + α × (T − Tref)]
Where:
- Rt = resistance at temperature T (Ω)
- Rref = resistance at the reference temperature (Ω)
- α = temperature coefficient of resistance
- T = measured temperature (°C)
- Tref = reference temperature (°C)
This equation allows you to determine resistance at a given temperature or calculate temperature when resistance is known.
Example RTD Temperature Calculation
Consider a Pt100 RTD sensor with the following parameters:
- Reference resistance: 100 Ω at 0°C
- Temperature coefficient: 0.00392
- Measured temperature: 35°C
The calculation would be:
Rt = 100 Ω × [1 + (0.00392 × 35)] = 113.72 Ω
All RTD equations use Celsius by default. If needed, temperature can be converted to Fahrenheit using:
°F = (°C × 9/5) + 32
Final Thoughts
Understanding how RTD resistance relates to temperature gives you greater confidence in sensor readings and system performance. Whether you rely on calculations or automated tools, accurate RTD conversion is essential for precision temperature measurement.
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