Linear Regulator Thermal Calculator
Estimate regulator dissipation and steady junction temperature through an entered series thermal-resistance path.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Separate load voltage-drop dissipation and input quiescent dissipation, then apply the entered thermal series path.
P=(Vin−Vout)Iout+Vin Iq; Tj=Tambient+P(θjc+θcs+θsa)
Worked example
12 V to 5 V at 0.5 A with 5 mA quiescent current dissipates 3.56 W; 14 K/W total resistance at 25°C gives 74.84°C modeled junction temperature.
Assumptions and input details
Input must exceed output. Constant current, constant thermal resistances and steady state; dropout, derating, thermal shutdown, PCB parallel paths and component ratings are excluded.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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