Select Conversion Parameters
Mode
Please enter a valid value. Temperature must be between -200°C and 850°C (Resistance between 18.49 Ω and 390.48 Ω).
CONVERSION RESULTS
R0 Nominal Resistance
100.00 Ω @ 0°C
Input Parameters Specification
Input Value FieldAccepts custom temperatures in Celsius (°C) or core conductor resistance values in Ohms (Ω) depending on selection.
Standard R0 ResistanceThe nominal electrical resistance of the platinum RTD sensor at exactly 0°C, standardly 100.00 Ohms.
DIN / IEC Standard AlphaThe temperature coefficient coefficient α = 0.003851 defining standard platinum purity limits.
Average SensitivityThe active rate of change of resistance relative to temperature, averaging roughly 0.385 Ohms per °C.
Practical Operational Examples
Cryogenic Storage Monitoring
At cryogenic boundaries (-200°C), a standard PT100 probe displays a clean electrical resistance of exactly 18.49 Ohms.
Room Temperature Reference
Under standard ambient conditions (20°C), the RTD current path reads 107.79 Ohms, showing a linear increase.
Industrial Steam Boiler Checks
Steam lines at 100°C show a resistance of 138.51 Ohms, demonstrating standard predictable scaling factors.
High Temp Oven Systems
Inside heavy furnaces reaching 600°C, the PT100 sensor is certified to measure an active resistance of 313.59 Ohms.
Formulas & Mathematical Logic
Standard PT100 conversions rely on the Callendar-Van Dusen equations defined under IEC 60751 guidelines.
For T ≥ 0°C: R(T) = R0 × (1 + A × T + B × T^2)
For T < 0°C: R(T) = R0 × (1 + A × T + B × T^2 + C × (T - 100) × T^3)
Constants: A = 3.9083 × 10^-3, B = -5.775 × 10^-7, C = -4.183 × 10^-12
For reverse calculations (Resistance to Temperature), the system solves the quadratic formula analytically for positive ranges, and applies an iterative Newton-Raphson approximation for sub-zero ranges to achieve 100% precision.
How to Use This Calculator
Choose the conversion mode: Temperature to Resistance or Resistance to Temperature.
Enter your active input value in the numeric field.
Click the orange Calculate button to trigger the Callendar-Van Dusen algorithm.
Examine the primary output card to find the precise equivalent resistance or temperature.
Check the average sensitivity factor to evaluate signal tuning parameters.
About This Calculator
Instantly convert PT100 temperature and resistance based on IEC 60751 standards.
The CalcBoy PT100 RTD Calculator decodes standard platinum resistance thermometer parameters across high and low temperature limits.
A PT100 is a standard Resistance Temperature Detector (RTD) made of platinum, having a nominal resistance of exactly 100 Ohms at 0°C. Known for their extreme accuracy, reliability, and stability, RTDs are widely used in process automation, laboratory research, aerospace instruments, and heavy thermal control systems. Sizing thermal paths accurately depends on matching resistance measurements to exact temperature scales.
Unlike thermocouples which output millivolt signals, RTDs act as active resistors whose value increases predictably as temperature rises. The relationship is almost linear but follows a slightly curved logarithmic path defined by the Callendar-Van Dusen equations. Hand-checking these charts is tedious and slow during active calibration.
This dynamic tool automates the process in both directions. Engineers can enter any decimal temperature to find the exact Ohm rating, or enter a measured Ohm level on a multimeter to find the exact local temperature, avoiding lookup errors.
Main BenefitEliminates manual interpolations in massive index sheets.
Range SupportedCovers standard industrial limits from -200°C up to +850°C.
Precision LevelDelivers values mathematically rounded to standard tolerances.
Key ConstantFeatures standard DIN/IEC α = 0.003851 platinum wire constants.
Note: Real-world RTD wiring must also account for lead wire resistance (using 3-wire or 4-wire bridge configurations) to avoid measurement offset errors.
Standard PT100 Quick Reference Chart
Simplified lookup guide containing safe standard nominal resistance values for primary temperature steps.
| Temperature (°C) |
Resistance (Ω) |
Temperature (°C) |
Resistance (Ω) |
| -200°C | 18.49 Ω | 100°C | 138.51 Ω |
| -150°C | 39.72 Ω | 150°C | 157.31 Ω |
| -100°C | 60.26 Ω | 200°C | 175.86 Ω |
| -50°C | 80.31 Ω | 300°C | 212.05 Ω |
| 0°C | 100.00 Ω | 400°C | 247.09 Ω |
| 50°C | 119.40 Ω | 600°C | 313.71 Ω |
Frequently Asked Questions
1. What does PT100 stand for?
"PT" indicates that the active sensor wire element is made of Platinum, and "100" signifies its nominal electrical resistance is exactly 100.00 Ohms at a temperature of 0°C.
2. What is the difference between Class A and Class B PT100 sensors?
These classes define accuracy tolerances. Class A is highly precise, offering an accuracy of ±0.15°C at 0°C. Class B is standard, offering an accuracy of ±0.30°C at 0°C.
3. Why do RTD systems use 3-wire or 4-wire connections?
Connecting wires have their own small resistances that can offset temperature readouts. Adding a 3rd or 4th wire allows the controller's Wheatstone bridge to measure and subtract lead wire resistance automatically.
4. What is the difference between PT100 and PT1000 sensors?
A PT1000 is also a platinum RTD but is rated at a nominal 1000.00 Ohms at 0°C. The higher base resistance increases its sensitivity (10 times more change per degree) and reduces lead wire offset issues.
5. What are the Callendar-Van Dusen coefficients for standard PT100?
According to IEC 60751, the standard coefficients are: A = 3.9083 × 10^-3, B = -5.775 × 10^-7, and C = -4.183 × 10^-12 (for sub-zero scales only).
6. Can I use a standard multimeter to check a PT100 sensor?
Yes. By measuring the sensor's resistance across its terminals and entering that value into our converter tool, you can easily verify if the sensor is operating accurately at local ambient temperatures.
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