Choose a mode in the calculator above, then enter the required inputs to estimate temperature (or temperature rise). Converting current to temperature depends on the real setup (for example: a 4–20 mA transmitter mapping, a heater with a known thermal resistance, or PCB trace heating estimates).
Amps To Temperature Formula
Current through a resistance generates heat (power) via Joule heating. Converting that heat into a temperature (or temperature rise) requires additional information such as time and heat capacity (transient/adiabatic estimate) or a thermal resistance to ambient (steady-state estimate).
\Delta T=\frac{P\,t}{m\,c}=\frac{I^{2}R\,t}{m\,c}\quad(\text{ideal, no losses}),\qquad \Delta T\approx P\theta=I^{2}R\theta,\qquad T\approx T_{amb}+\Delta TVariables:
- ΔT is the temperature rise (°C or K)
- T is the final temperature (typically reported in °C or °F)
- Tamb is the ambient temperature (°C or °F)
- I is the current in amps (A)
- R is the resistance in ohms (Ω)
- P is electrical power dissipated as heat (W), where P = I²R
- t is heating time (s)
- m is mass being heated (kg)
- c is specific heat capacity (J/(kg·°C))
- θ is thermal resistance to ambient (°C/W)
With current and resistance alone you can calculate power: P = I²·R (watts). To estimate a temperature rise, you must also include a thermal model (for example, ΔT ≈ P·θ for a steady-state estimate, or ΔT = P·t/(m·c) for an idealized transient estimate without losses).
| Amps (A) | Power (W) | Estimated rise ΔT (°C) | Estimated rise ΔT (°F) |
|---|---|---|---|
| 0.05 | 0.003 | 0.050 | 0.090 |
| 0.10 | 0.010 | 0.200 | 0.360 |
| 0.20 | 0.040 | 0.800 | 1.440 |
| 0.25 | 0.063 | 1.250 | 2.250 |
| 0.30 | 0.090 | 1.800 | 3.240 |
| 0.50 | 0.250 | 5.000 | 9.000 |
| 0.75 | 0.563 | 11.250 | 20.250 |
| 1 | 1.000 | 20.000 | 36.000 |
| 1.5 | 2.250 | 45.000 | 81.000 |
| 2 | 4.000 | 80.000 | 144.000 |
| 2.5 | 6.250 | 125.000 | 225.000 |
| 3 | 9.000 | 180.000 | 324.000 |
| 4 | 16.000 | 320.000 | 576.000 |
| 5 | 25.000 | 500.000 | 900.000 |
| 6 | 36.000 | 720.000 | 1296.000 |
| 7.5 | 56.250 | 1125.000 | 2025.000 |
| 8 | 64.000 | 1280.000 | 2304.000 |
| 9 | 81.000 | 1620.000 | 2916.000 |
| 10 | 100.000 | 2000.000 | 3600.000 |
| 12 | 144.000 | 2880.000 | 5184.000 |
| * Rounded to 3 decimals. Assumes fixed resistance R = 1 Ω. Power: P (W) = I (A)² × R (Ω). Temperature rise estimate uses a chosen thermal resistance θ = 20 °C/W: ΔT (°C) ≈ P × θ. A temperature rise in °F is ΔT°F = ΔT°C × 1.8 (no +32). Values are illustrative only; real temperatures depend strongly on mounting, airflow, heat spreading, and component ratings. | |||
What is the Relationship Between Amps and Temperature?
The relationship between current (amps), resistance, and temperature is commonly discussed using Joule heating. A current flowing through a resistance dissipates electrical power as heat: P = I²R. That heat can raise temperature, but the actual temperature (or temperature rise) also depends on how long the power is applied and how effectively heat is stored and removed (mass/heat capacity, conduction to a heatsink or PCB, convection/airflow, radiation, etc.).
How to Calculate Temperature from Amps and Resistance?
The following steps outline how to estimate temperature (or temperature rise) from current and resistance using a simple thermal model.
- Determine the current in amps (I).
- Determine the resistance in ohms (R).
- Calculate power dissipated as heat: P = I² × R (watts).
- Choose a thermal model:
- Steady-state estimate: pick a thermal resistance θ (°C/W) and ambient temperature Tamb, then compute ΔT ≈ P·θ and T ≈ Tamb + ΔT.
- Ideal transient (no losses): pick time t, mass m, and specific heat c, then compute ΔT = P·t/(m·c).
- Calculate the final value and compare with the calculator above (using the matching mode/assumptions).
Example Problem :
Use the following variables as an example problem to test your knowledge (steady-state estimate using thermal resistance).
Current (I) = 0.2 A
Resistance (R) = 10 Ω
Ambient temperature (Tamb) = 25 °C
Thermal resistance (θ) = 100 °C/W
Temperature (T) = ?