Match the reference to the application.
The controller matches the required 20 kΩ NTC curve. Review reference-point tolerance and curve uncertainty across the operating interval.
Review the specification →GUILCOR · NTC thermistors
20 kΩ NTC
Build a temperature-dependent error budget.
A 20 kΩ nominal value does not define an accuracy class. Explore how resistance, curve and readout tolerances combine across temperature.
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Understand the reference
What defines a 20 kΩ NTC?
20 kΩNominal resistance at 25 °C
NegativeResistance decreases as temperature rises
Curve + packageBoth must match the application
The R25 tolerance is specified at a reference point. Curve uncertainty matters increasingly away from that point, while readout errors add their own contribution. A single percentage cannot stand in for the full temperature error.
A 20 kΩ NTC is a negative temperature coefficient thermistor with a nominal resistance of 20,000 Ω at 25 °C (R25). The value is a reference point, not a fixed resistance during use. Select the resistance–temperature characteristic together with tolerance, excitation and the completed probe construction.
SELECTION / YOUR APPLICATION
Is 20 kΩ NTC the right starting point?
Review 30 kΩ NTC alongside 20 kΩ NTC.
Compare the nominal resistance, reference temperature and full R/T characteristic. Matching at one temperature does not establish a compatible replacement over the operating interval.
Explore 30 kΩ NTC →Keep the complete specification together.
Keep the controller reference and the specified NTC curve together. Check tolerances, cable and probe construction rather than selecting by resistance or connector alone.
Prepare your enquiry →These links support a specification review. They do not establish interchangeable parts or availability of a complete assembly.
Application check
Separate R25, β and readout tolerances.
Tool input range: -20 to 100
Tool input range: 0 to 10
Tool input range: 0 to 10
Tool input range: 0 to 5
The tool evaluates the extremes of an illustrative R25 tolerance, β tolerance and proportional resistance-readout error, then converts the corner values using the nominal curve.
Nominal resistance
Lowest indicated temperature
Highest indicated temperature
Temperature error interval
Enable JavaScript to calculate.
This is a worst-corner bound under independent bounded inputs, not a statistical RSS uncertainty or a manufacturer guarantee. It excludes self-heating, leads, installation and calibration-reference uncertainty.
Model equationRcorner = R₂₅(1 ± εR) × exp[β(1 ± εβ)(1/T − 1/298.15)] × (1 ± εread)
Use the part’s specified curve tolerance or R/T limits where provided instead of assuming independent R25 and β limits. Keep the electronics and mounting contributions visible in the final budget.
Operating principle
Read the characteristic, not just R25.
Illustrative resistance values
| Temperature | Resistance |
|---|---|
| -20 °C | 210,769.38 Ω |
| 0 °C | 67,241.21 Ω |
| 25 °C | 20,000.00 Ω |
| 50 °C | 7,176.37 Ω |
| 85 °C | 2,173.34 Ω |
| 100 °C | 1,395.04 Ω |
From resistance to temperature
The constant-β approximation uses R(T) = R25 × exp[β(1/T − 1/298.15)], with absolute temperature in kelvin. It is useful for comparing circuit assumptions; a real part may need its specified R/T table or Steinhart–Hart coefficients for the required interval.
For Steinhart–Hart, 1/T = A + B ln(R) + C[ln(R)]³. Use coefficients and resistance units supplied for the selected part. A coefficient labelled B here is not automatically the same as a thermistor’s β value.
The temperatures in this example are calculation points, not an operating-temperature rating. Confirm the element, cable, seals and assembled probe limits.
A higher nominal value does not by itself reduce coefficient tolerance or long-term drift. Compare documented parts over the intended temperature range.
Selection checklist
Specify the complete sensing assembly.
Electrical and thermal requirements
- R25 tolerance and the exact R/T curve, β interval or coefficients.
- Required temperature interval and complete measurement error budget.
- Measuring current, allowable dissipation and self-heating under the actual mounting conditions.
- Response time with its stated medium, flow and test method; no universal response time follows from R25.
- Ageing, drift and environmental qualification documented for the selected part.
Mechanical and installation requirements
- Element or assembled probe dimensions, sheath and contact arrangement.
- Cable length, insulation, connector and total two-wire loop resistance.
- Sealing, media compatibility, pressure and ingress requirements where applicable.
- Controller curve support, supply, input range, loading and acquisition timing.
- Calibration points and required documentation for the final assembly.
Wiring and measurement
Connect the sensor and account for the circuit.
Example two-wire divider
Supply → fixed pull-up Rs → measurement node
Measurement node → NTC → ground
ADC measures the node relative to ground
For an unloaded input, Vout = Vs × RNTC / (Rs + RNTC). In this arrangement, warming an NTC lowers the output voltage. The element has no polarity, although an assembled cable or connector can have a specified pin assignment.
Separate electrical and thermal errors
Lead resistance, leakage, finite input impedance and sampling transients can alter the measured signal. Measuring current also dissipates power in the element: P = I²R. The approximate steady-state self-heating rise is P/δ when the dissipation factor δ applies to the actual installation.
A robust coating or sheath can improve environmental protection while changing heat transfer. Validate the completed probe in its intended medium instead of carrying over the bare element’s response figure.
Application contexts
Where to evaluate a 20 kΩ NTC.
Precision embedded control
Allocate an error budget between the element, input and installation.
Climate monitoring
Define acceptable error over seasonal conditions, not only room temperature.
Laboratory and instrument probes
Confirm calibration points, traceability and the complete assembly specification.
Application examples are selection contexts. Suitability and any required certification depend on the identified reference and completed assembly.
Probe construction
Choose the installation format.
Match the sensing point, medium and mounting to the probe construction. These links explore construction families; confirm the required NTC characteristic when requesting a reference.
Frequently asked questions
20 kΩ NTC questions.
Does ±1% resistance tolerance mean ±1 °C?
No. Temperature error depends on the local slope of the characteristic and the temperature. Curve tolerance and readout errors also contribute.
Is every 20 kΩ NTC interchangeable?
No. Match R25, the complete curve and tolerances, then verify electrical excitation, construction, cable, environmental limits and controller configuration.
Can the example values replace a product datasheet?
No. The table and tool illustrate stated assumptions. Use the selected reference’s data, curve and test conditions for specification and validation.
What information should I send for a probe request?
Include the required R25 and curve, temperature range, allowable error, medium, mounting, dimensions, cable and connector, controller input and expected quantity.
Technical background: Manufacturer guidance on sensing and readout. Example calculations are educational models with the assumptions stated above.
GUILCOR / YOUR ENQUIRY
Define your 20 kΩ NTC enquiry.
Send the electrical reference and the installation details together. A nominal resistance alone does not define the right replacement or assembled probe.
Missing a reference or datasheet?
Send the component marking, equipment reference and any photographs or documents you have. These provide a starting point for identifying what must be confirmed.
The outline helps prepare your enquiry. Copying it does not send a request.
FOUR DETAILS THAT MOVE THE DISCUSSION FORWARD
01
Sensor and controller
Part number, nominal resistance and reference temperature, R/T data or specified β interval, tolerance and controller input.
02
Measurement conditions
Operating and peak temperatures, required accuracy and response target, measured medium and exposure to moisture or cleaning.
03
Assembly and connection
Probe dimensions, mounting or insertion, cable length and insulation, connector or lead termination. Attach a drawing or photo.
04
Project and validation
Sample and production quantities, target delivery, calibration or documentation needs, and the checks required before approval.