PT100 vs PT1000: Choosing the Right RTD Temperature Sensor
PT100 and PT1000 sensors use the same resistance-based temperature principle, but their electrical scales differ by a factor of ten. A PT100 is nominally 100 ohms at 0 C; a PT1000 is 1000 ohms. This difference matters most when lead resistance cannot be compensated or excitation current must stay low.
This guide compares nominal resistance, sensitivity, lead-wire error, wiring, IEC 60751 tolerance classes, and self-heating without treating either resistance value as universally more accurate.
Related: industrial sensors and RTD vs thermocouple.
TL;DR: PT100 is 100 ohms at 0 C with nominal sensitivity of about 0.385 ohms/C; PT1000 is 1000 ohms with about 3.85 ohms/C. In an uncompensated circuit, 1 ohm of lead resistance represents about 2.6 C error for PT100 and 0.26 C for PT1000. Choose the element and wiring together, then verify both against the measuring instrument.
What Is the Difference Between PT100 and PT1000?
The names state the nominal resistance at 0 C: 100 ohms for PT100 and 1000 ohms for PT1000. Their nominal sensitivities are about 0.385 and 3.85 ohms/C respectively (HT-Heater).
The tenfold electrical scale is the useful distinction. A PT1000 produces a larger resistance change for the same temperature change, so a fixed unwanted series resistance causes one tenth of the temperature error. This does not make every PT1000 installation more accurate; sensor tolerance, wiring, excitation, input circuit, and installation still affect the result.
Why Does PT1000 Reduce Lead-Wire Error?
An RTD instrument infers temperature from resistance. In an uncompensated two-wire connection, both leads are in series with the sensing element, so the instrument cannot distinguish their resistance from the sensor's.
Each ohm of uncompensated lead resistance causes about 2.6 C of error for a PT100 and 0.26 C for a PT1000 (HT-Heater). This comparison follows the tenfold difference in sensitivity.
Evaluate a cable run by its measured or calculated loop resistance, not distance alone. Conductor material, cross-section, temperature, terminals, and splices all affect the resistance presented to the instrument.
2-Wire vs 3-Wire vs 4-Wire RTD Wiring: What's the Difference?
The wiring choice determines how the instrument handles lead resistance.
2-wire is the simplest connection but provides no lead-resistance compensation. The instrument measures the sensor and both leads together. Use it only when the resulting error fits the complete measurement budget (Tempsens).
3-wire compensation adds a conductor and assumes the relevant lead resistances match. Conductor gauge, length, terminals, and repairs therefore matter: unequal leads leave residual error (Orion Technical Solutions).
4-wire (Kelvin) uses separate current and voltage-sense paths. Because the sense input draws negligible current, lead resistance does not enter the measured voltage drop across the RTD. Choose it when lead-resistance error must be removed from the measurement (Tempsens).
Do not assume wiring methods are interchangeable. Confirm that the transmitter, input card, or meter supports the selected element and connection.
How Accurate Is Each RTD, and What Do IEC 60751 Classes Mean?
IEC 60751 defines tolerance classes for industrial platinum resistance thermometers (IEC 60751; Beamex). The element class is only one part of installed accuracy.
Do not copy a class coefficient from a summary and use it as the loop specification. Confirm the class formula and valid temperature interval for the actual element from the applicable standard and manufacturer's data sheet. Then add the instrument, excitation, wiring, mounting, and calibration contributions required by the application.
A tighter element tolerance does not dictate a wire count. Three- or four-wire measurement is often chosen when uncompensated lead error would consume too much of the budget, but the decision should follow the actual circuit's error budget.
How Do Self-Heating and Excitation Current Compare?
Measuring an RTD requires excitation current, and power dissipated in the element can raise its temperature above the medium. A PT1000 can use a lower current while producing a usable signal, reducing the self-heating burden compared with a PT100 measurement designed for a similar signal level (Beamex; HT-Heater).
No current setting fits every PT100 or PT1000. Use the instrument's specified excitation and the probe manufacturer's self-heating data, then consider how well the installation transfers heat to the process.
Does Element Construction Change the Choice?
Element construction is separate from nominal resistance. This packet does not establish universal thin-film versus wire-wound limits or performance rankings. Compare the chosen parts' temperature range, response, vibration tolerance, stability, dimensions, and calibration data instead of inferring these properties from “PT100” or “PT1000.”
When Should You Use PT100 vs PT1000?
Decide from the error budget and available input hardware.
Choose PT1000 when uncompensated lead resistance matters and the available wiring cannot remove it, or when lower excitation current is valuable. Choose PT100 when the installed transmitter or control input supports it and the selected wiring meets the accuracy requirement.
Neither choice removes the compatibility check. Confirm nominal resistance, wiring mode, tolerance class, excitation, temperature range, and transmitter configuration on the actual data sheets.
PT100 vs PT1000 at a Glance
| Attribute | PT100 | PT1000 |
|---|---|---|
| Nominal resistance at 0 C | 100 ohms | 1000 ohms |
| Nominal sensitivity | About 0.385 ohms/C | About 3.85 ohms/C |
| Error per 1 ohm uncompensated lead resistance | About 2.6 C | About 0.26 C |
| Lead-resistance strategy | Compensate it or include it in the budget | Tenfold smaller temperature effect, but still include it |
| Excitation | Verify instrument and element data | Lower current can provide a usable signal |
| Accuracy classes | IEC 60751 classes apply | IEC 60751 classes apply |
Frequently Asked Questions
What is the difference between PT100 and PT1000?
A PT100 has a nominal resistance of 100 ohms at 0 C and sensitivity of about 0.385 ohms/C. A PT1000 is 1000 ohms at 0 C and about 3.85 ohms/C (HT-Heater).
What is the difference between 2-wire, 3-wire, and 4-wire RTD wiring?
Two-wire measurement includes lead resistance. Three-wire compensation assumes matched leads. Four-wire Kelvin measurement separates current and sense paths so lead resistance is excluded from the resistance measurement (Tempsens).
How big is RTD lead-wire error?
One ohm of uncompensated lead resistance corresponds to about 2.6 C error for PT100 and 0.26 C for PT1000 (HT-Heater). Calculate the actual circuit rather than assuming a particular cable length produces a fixed error.
Does PT1000 reduce self-heating?
PT1000 can use a lower excitation current for a usable measurement signal, reducing its self-heating burden. Actual error depends on excitation power and how effectively the installed probe sheds heat to the measured medium.
What are IEC 60751 accuracy classes?
IEC 60751 defines tolerance classes for industrial platinum resistance thermometers. Use the applicable standard and the chosen element's data sheet for the exact class formula and valid range; then account for wiring and instrument error separately.
Selection Rule
PT1000's tenfold sensitivity reduces uncompensated lead-wire error and permits lower excitation for a usable signal. PT100 remains a sound choice when compatible hardware and compensated wiring meet the measurement budget.
Related: industrial sensors, RTD vs thermocouple, and thermocouple types.
What is the difference between PT100 and PT1000?
A PT100 has a nominal resistance of 100 ohms at 0 C and changes by about 0.385 ohms per C. A PT1000 is 1000 ohms at 0 C and changes by about 3.85 ohms per C. The larger signal makes uncompensated lead resistance less significant.
What is the difference between 2-wire, 3-wire, and 4-wire RTD wiring?
A 2-wire measurement includes lead resistance. A 3-wire circuit compensates for it by assuming matched leads. A 4-wire Kelvin circuit separates current and voltage-sense paths so lead resistance is excluded from the resistance measurement.
How big is RTD lead-wire error?
For an uncompensated measurement, 1 ohm of lead resistance corresponds to about 2.6 C of error for a PT100 and about 0.26 C for a PT1000.
Does PT1000 reduce self-heating?
A PT1000 can produce a usable measurement signal at a lower excitation current than a PT100. Lower current reduces the self-heating burden, although the actual error still depends on the probe, medium, installation, and measuring instrument.
What are IEC 60751 accuracy classes?
IEC 60751 defines tolerance classes for industrial platinum resistance thermometers. Check the class and permitted temperature range on the selected element data sheet, then include wiring and instrument error in the installed-loop accuracy budget.
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