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Heat Sink Thermal Calculator — Free Online Tool

Junction temp from thermal resistance R_θ

Junction temperature from power dissipation, thermal resistance (junction-to-case, case-to-sink, sink-to-ambient), ambient. Electronics design tool.

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Heat Sink Thermal Calculator

Junction temperature from power × thermal resistance + ambient. Check T_J vs T_Jmax with safety margin. Required heatsink R_θSA for given specs.

How to use this tool

  1. 1

    Power dissipation

    Component power in watts.

  2. 2

    Thermal resistances

    Junction-to-case, case-to-sink, sink-to-ambient.

  3. 3

    Junction temperature

    Compare to T_jmax.

Frequently Asked Questions

Why R_θJC + R_θCS + R_θSA?
Heat flows in series: junction → case → heatsink → ambient. Each interface has thermal resistance. Total R_θJA = sum. T_J = T_A + (P × R_θJA).
How to choose heatsink R_θSA?
Required R_θSA = (T_Jmax - T_A)/P - R_θJC - R_θCS. Below required = OK. Smaller R_θSA = larger/finned heatsink. Add safety margin (T_Jmax - 25°C).
Thermal interface material?
Thermal grease ~0.5°C/W contribution. Thermal pad ~1-2°C/W. No interface = 5-10°C/W (terrible). For high-power: phase-change pad or grease + good clamping.

Key Takeaways

  • Heat Sink Thermal Calculator is a free, browser-based calculator tool — junction temp from thermal resistance r_θ.
  • No signup, no downloads, no file uploads — your data stays on your device.
  • Works on desktop, tablet, and mobile. Install as a PWA for offline access.

How to Use Heat Sink Thermal Calculator

  1. Open the tool: Launch Heat Sink Thermal Calculator on Toololis — no account or download needed.
  2. Enter your data: Paste text, enter values, or select a file directly in your browser.
  3. Get instant results: Everything is processed locally — results appear immediately.
  4. Copy or download: Save your output or share it. Bookmark for quick access next time.

Heat Sink Thermal Calculator — Quick Facts

Price
Free — no limits, no watermarks, no paywalls
Privacy
100% browser-based — no data is sent to any server
Platform
Any modern browser on desktop, tablet, or mobile
Category
Calculator Tools on Toololis
Offline
Works offline after first visit (Progressive Web App)
FeatureDetails
ToolHeat Sink Thermal Calculator
CategoryCalculator
Signup RequiredNo
File UploadNone — processed in browser
Mobile SupportFully responsive
CostFree forever

Why Use Heat Sink Thermal Calculator?

You should try Heat Sink Thermal Calculator for a quick, private way to junction temp from thermal resistance r_θ. All processing happens in your browser. Your files and data never leave your device. According to web.dev, client-side processing is the gold standard for privacy.

On the other hand, dedicated APIs or desktop tools suit batch processing better. They also handle server-side automation. For everyday tasks, browser tools offer the best speed, privacy, and convenience.

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100% Privacy. This tool runs entirely in your browser. Your data is never uploaded to any server.