CPU Thermal Calculator
Estimate CPU operating temperature and thermal throttling risk under sustained load.
About CPU Thermal Calculator
A simplified steady-state thermal model treats the temperature rise above ambient as proportional to power dissipated times the cooling solution's thermal resistance (°C per watt) — lower thermal resistance means a more effective cooler (better heatsink contact, more airflow, or liquid cooling) for the same power draw. Comparing the resulting estimated temperature against the CPU's throttle threshold (Tjmax, typically 90-100°C on modern consumer/server CPUs) flags when sustained load is likely to trigger automatic frequency/voltage reduction — a protective mechanism that trades performance for staying within safe operating temperature, often the underlying cause of unexplained performance drops under sustained load.
Formula
Steady-state temperature estimate
temperature = ambient_temp + (power_draw × thermal_resistance)
- T_{ambient}
- ambient temperature
- P
- power draw (watts)
- R_{th}
- thermal resistance (°C/W)
Worked example
With the default values below, CPU Thermal Calculator returns Estimated CPU Temperature (°C) of 48.75. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Ambient Temperature (°C)accepts -10–60
- 25
- CPU TDP / Current Power Draw (W)minimum 1
- 95
- Thermal Resistance (°C/W, cooler-dependent)minimum 0.01
- 0.25
- Throttle Threshold / Tjmax (°C)accepts 50–130
- 95
Results
- Estimated CPU Temperature (°C)
- 48.75
- Throttle Risk Assessment
- Comfortable margin — 46.3°C below throttle threshold under these conditions.
- Margin to Throttle Threshold (°C)
- 46.25
- Throttling Likely?
- false
Step by step
- 1Values used
- 2Steady-state temperature estimate
- 3Estimated CPU Temperature (°C)= 48.75
- 4Throttle Risk Assessment= Comfortable margin — 46.3°C below throttle threshold under these conditions.
- 5Margin to Throttle Threshold (°C)= 46.25
- 6Throttling Likely?= No
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why does my CPU throttle even though ambient room temperature seems fine?
Throttling depends on the CPU die/package temperature, not room temperature — sustained high power draw combined with insufficient cooling (dust-clogged heatsink, dried thermal paste, inadequate case airflow) can push die temperature to the throttle threshold even in a cool room, since the thermal resistance term dominates the equation at high sustained wattage.
How can I check my actual CPU temperature and throttle events on Linux?
`sensors` (from lm-sensors, after running `sensors-detect`) shows live per-core temperatures, and checking `dmesg` for 'thermal' or 'throttl' related messages, or watching `/sys/class/thermal/thermal_zone*/temp`, can reveal whether throttling events have actually occurred historically.
Is a lower thermal resistance always better?
Yes for thermal headroom, but it comes with tradeoffs — better cooling (lower R_th) typically means larger heatsinks, more fans (more noise), or liquid cooling (more cost and complexity), so the right choice balances thermal headroom against noise, cost and physical space constraints rather than minimizing R_th unconditionally.