whatwatts

whatwatts is a lightweight macOS menu bar app for answering one simple question: what is your Mac actually doing right now when you plug in a charger?

It keeps the original WhatWatt idea of showing negotiated adapter wattage, and adds the missing half of the picture: live battery charge and discharge rate.

It also includes an optional system-power estimate sourced from the Mac's SMC, inspired by SAP's Power Monitor app.

Screenshots

Menu bar app:

Preferences:

Built on top of SomeInterestingUserName/WhatWatt by Jiawei Chen. The original MIT license is preserved. The upstream PR intentionally keeps the original app name; this public repo uses the whatwatts branding.

Highlights

• Shows adapter wattage and battery power flow in one compact menu bar item
• Can also show an optional SMC system-power estimate in the menu bar
• Uses a clean title format like 67W | ↑18.4W | 23.1W
• Defaults to a low-power refresh mode with fast updates only when charger state changes

Why this fork exists

The original app is great at showing what the charger negotiated with macOS. This fork adds the part that is often more useful in practice: whether the battery is actually charging or discharging, and by how much.

That makes it easier to compare chargers, cables, docks, and multi-port power bricks without opening a larger system utility.

The optional system-power estimate came from looking at how SAP Power Monitor approaches the same problem. whatwatts now reads the same class of private SMC value to expose a lightweight "how hard is the machine pulling right now?" estimate alongside charger and battery data.

In low-power mode, the app checks infrequently to stay lightweight. After plugging or unplugging a charger, it updates once a second for 20 seconds. The SMC system-power value is shown as a 60-second average unless Always Live Updates is enabled.

SMC system power note

The SMC system-power readout is an estimate exposed through private Apple interfaces, not a public supported API.

• It is useful today and was tested working on an Intel Mac.
• It may stop working in a future macOS release or on different hardware generations.
• If it does, adapter and battery readings should continue to work normally.

Trust and first launch

The full app source is public in this repo, so you can inspect exactly what it does before running it.

whatwatts is not notarized because this project is not being shipped under a paid Apple Developer account. That means macOS may block it on first launch until you explicitly allow it.

If you want to open it manually through macOS:

1. Try to open the app once.
2. When macOS says it cannot be opened, dismiss the warning.
3. Open System Settings > Privacy & Security.
4. Scroll down to the Security section.
5. Find the message saying the app was blocked from opening.
6. Click Open Anyway.
7. Confirm by clicking Open in the follow-up dialog.

Apple's guidance for this flow:

• Safely open apps on your Mac

If you prefer Terminal, there are two ways to do it:

• Use a test run command if you just want to launch whatwatts from ~/Downloads first. This does not need an administrator password.
• Use an install command if you want to move it into /Applications. This usually asks for an administrator password because it writes to /Applications.

Pick the command that matches your Mac, paste it into Terminal, and press Return.

Intel test run:

curl -L https://github.com/git-anish/whatwatts/releases/download/v1.0.1/whatwatts-intel.zip -o ~/Downloads/whatwatts-intel.zip && ditto -x -k ~/Downloads/whatwatts-intel.zip ~/Downloads && xattr -dr com.apple.quarantine ~/Downloads/whatwatts-intel.app && open ~/Downloads/whatwatts-intel.app

Apple Silicon test run:

curl -L https://github.com/git-anish/whatwatts/releases/download/v1.0.1/whatwatts-apple-silicon.zip -o ~/Downloads/whatwatts-apple-silicon.zip && ditto -x -k ~/Downloads/whatwatts-apple-silicon.zip ~/Downloads && xattr -dr com.apple.quarantine ~/Downloads/whatwatts-apple-silicon.app && open ~/Downloads/whatwatts-apple-silicon.app

Intel install:

curl -L https://github.com/git-anish/whatwatts/releases/download/v1.0.1/whatwatts-intel.zip -o ~/Downloads/whatwatts-intel.zip && ditto -x -k ~/Downloads/whatwatts-intel.zip ~/Downloads && sudo rm -rf /Applications/whatwatts.app && sudo mv ~/Downloads/whatwatts-intel.app /Applications/whatwatts.app && sudo xattr -dr com.apple.quarantine /Applications/whatwatts.app && open /Applications/whatwatts.app

Apple Silicon install:

curl -L https://github.com/git-anish/whatwatts/releases/download/v1.0.1/whatwatts-apple-silicon.zip -o ~/Downloads/whatwatts-apple-silicon.zip && ditto -x -k ~/Downloads/whatwatts-apple-silicon.zip ~/Downloads && sudo rm -rf /Applications/whatwatts.app && sudo mv ~/Downloads/whatwatts-apple-silicon.app /Applications/whatwatts.app && sudo xattr -dr com.apple.quarantine /Applications/whatwatts.app && open /Applications/whatwatts.app

What the commands do:

• curl -L ... downloads the release zip from GitHub
• ditto -x -k ... unzips the app
• xattr -dr com.apple.quarantine ... removes macOS quarantine so the app can launch
• open ... launches the app
• sudo rm and sudo mv only appear in the install version because moving the app into /Applications usually needs admin access

Build

Xcode

1. Open WhatWatt.xcodeproj in Xcode.
2. Select the WhatWatt target.
3. Build on the machine architecture you want to ship.

For release builds:

• Intel: build on an Intel Mac to produce an x86_64 app
• Apple Silicon: build on an Apple Silicon Mac to produce an arm64 app

This is the supported path for whatwatts, and it is the path used for the published release builds.

Dependencies

whatwatts does not use third-party packages.

It depends on:

• macOS 10.13 or newer
• Xcode for release-quality Intel and Apple Silicon app bundles
• AppKit/Cocoa and IOKit, both provided by macOS

Releases

The clean distribution strategy is to publish separate binaries by architecture.

• Intel release: build and ship an x86_64 app bundle on Intel
• Apple Silicon release: build and ship an arm64 app bundle on Apple Silicon
• Universal release: optional later, only if both sides are built and verified first

That keeps releases explicit and avoids shipping cross-compiled binaries that were never tested on their native platform.

License and credit

Original project:

• Author: Jiawei Chen
• Repo: SomeInterestingUserName/WhatWatt
• License: MIT

This fork remains under the MIT license. See LICENSE.