WattBar shows the real power flowing into your MacBook — live, to the watt. A tiny native utility that feels like it shipped with macOS.
The menu bar stays compact and readable. One click opens a calm popover with the full picture — direction of flow, battery, adapter, the lot.
The live wattage flowing into the battery.
Switches to the battery percentage when unplugged.
Quiet glyphs when there's nothing flowing.
Reads the battery's real voltage and amperage straight from IOKit and shows the true power flow — not the adapter's rated number.
A green ⊕ when power flows in, an orange ⊖ when it drains out. You always know which way the energy is going.
Percentage, voltage, amperage, adapter, cycle count, temperature, and time to full or empty.
One native toggle. Registers through SMAppService — no helper hacks.
Lives only in the menu bar. Nothing in the Dock, nothing in your way.
Event-driven updates from the power-source notification, plus a gentle timer that relaxes when you're not looking. No subprocesses, no polling loops, no third-party dependencies.
WattBar reads the AppleSmartBattery
entry in the I/O Registry and computes the true power flow itself.
Just IORegistryEntryCreateCFProperties on the smart-battery service.
An IOPSNotification run-loop source refreshes the moment your power state changes.
No battery? On a desktop Mac it simply shows a clean plug glyph instead of guessing.
Positive while charging, negative while discharging. That single signed number is what drives the whole UI — the menu bar label, the flow icon, and the gauge.
Grab WattBar-latest.dmg — about 0.8 MB.
Open the disk image and drop WattBar onto the Applications folder.
Open WattBar — it appears in your menu bar. Flip on Launch at Login and forget about it.
xattr -dr com.apple.quarantine /Applications/WattBar.app. After that it opens normally.
Free, open source, and about the size of a photo. Give your menu bar a superpower.