PowerLens is a menu bar app for Apple silicon Macs. It shows how power moves between your charger, your battery, and your Mac, and says what is happening in plain language: whether the charger is enough, how much is going into the battery, and when the battery has to help. Everything it measures stays on your Mac.
Click the menu bar item for a quick check:
- Status in plain words, such as Charging the battery: 21.4W goes to your Mac and 27.6W into the battery.
- Power flow drawn as soft strands whose width follows the watts. The battery joins the picture only while it is charging or supplying power.
- Battery, maximum capacity, and temperature at a glance.
- Apps using significant energy, up to three, sampled only while the popover or Dashboard is open.
- Energy mode (Automatic, Low Power, or High Power), with a shortcut to Battery settings.
- Details on demand: capacities, cycles, voltage and current, and charger output.
The menu bar item itself comes in five styles: Detailed, Simple, Battery Icon, Percent Inside (the macOS 27 battery, with the level and charging state inside the icon), and Icon Only. In Low Power Mode the battery and the Detailed style's symbol turn yellow, as the battery does in macOS, and a red badge appears when not enough power is coming in.
The Dashboard gives the same readings more room across three pages.
- Now: the power flow, battery, charger, and Mac power cards, a chart of the last hour, and notes about battery health, temperature, and the app using the most energy.
- Battery: maximum capacity compared with the original, charge cycles against the design target, temperature (warm from 36°C, hot from 40°C), and the charging setting macOS is applying, such as a charge limit or Optimized Battery Charging.
- History: 24 hours, 7 days, 30 days, or everything, with summary numbers, charts you can scrub, and long-term battery health and cycle trends. Export the saved samples as CSV or JSON.
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PowerLens watches the power flow over time instead of reacting to every sample:
| Status | What it means |
|---|---|
| Charging the battery | The charger covers the Mac and sends the rest into the battery. |
| The charger is enough | The charger covers the Mac while the battery rests. |
| Battery is helping out briefly | A short load spike draws on the battery. This is normal. |
| Not enough power coming in | The Mac keeps using more than comes in, and the battery covers the difference. PowerLens reports what it measures and does not guess whether the charger, cable, or dock is the cause. |
| Running on battery | Shows the time left and what the Mac is using right now. |
Charge limits and Optimized Battery Charging get their own statuses. You can also turn on notifications for when not enough power is coming in or the battery gets hot.
- General: language (English or Korean), menu bar style, Dock icon, Open at Login, and notifications.
- Measurement & History: the measurement method (Automatic, Reliable, or More Precise) and how long history is kept.
- Updates: Stable or Alpha channel and automatic update checks.
Screenshots use the app's demo mode, which shows scripted readings so every part of the interface has something to display.
Power sensors on a Mac update at slightly different moments, so raw readings rarely add up. PowerLens calculates the displayed values from the system power reading, so charger, battery, and Mac power always balance and stay within the charger's rating. Hover over a value to see the original sensor readings and how it was calculated. History and diagnostics keep the original measurements.
A reading PowerLens cannot get is shown as unknown, never as a healthy default.
Battery power calculated from current and voltage is marked with ≈.
PowerLens reads battery and power information locally. It sends no analytics, telemetry, or crash reports, and it needs no account.
History is stored in a local SQLite database under
~/Library/Application Support/PowerLens. You choose how long full-detail
samples stay (30 days, 90 days, 1 year, or forever) and whether older data is
kept as hourly or daily summaries. See PRIVACY.md for exactly
what is read and stored.
- A Mac with Apple silicon (M1 or later). Intel Macs are not supported.
- macOS 26 or later. Tested on macOS 26.
- A built-in battery for battery readings.
- Xcode or the Xcode command line tools to build from source.
- Download the latest
PowerLens-<version>.dmgfrom Releases. - Open the DMG and drag
PowerLens.appintoApplications. - Launch PowerLens from
Applications.
Release builds are Developer ID signed and notarized. PowerLens checks for updates with Sparkle from the app menu or Settings.
Each release includes PowerLens-<version>-checksums.txt. Download it into the
same folder as the DMG, then run:
grep "PowerLens-<version>.dmg$" PowerLens-<version>-checksums.txt | shasum -a 256 -c -Quit PowerLens, then remove PowerLens.app from Applications. To delete
local history and preferences as well, follow
PRIVACY.md.
swift build --build-system native --arch arm64
./script/test_swiftpm.sh
./script/build_and_run.sh./script/build_and_run.sh builds dist/PowerLens.app and launches it. It must
run from a native Apple silicon shell; Rosetta and Intel hosts are rejected.
Pass debug, logs, telemetry, or verify for the helper modes documented
in the script. With Swift 6.3 or later, run
POWERLENS_BUILD_SYSTEM=swiftbuild ./script/test_swiftpm.sh to match the
SwiftBuild path in CI.
Debug builds also accept --demo, which replaces live readings and history
with scripted ones. docs/assets/screenshots
explains how the README screenshots are captured. Release packaging notes for
maintainers live in Packaging/README.md.
Read CONTRIBUTING.md before opening an issue or pull request.
Ordinary changes target develop.
Report suspected vulnerabilities privately through GitHub Security Advisories instead of a public issue. See SECURITY.md for the process.
Copyright (C) 2026 HYEONJIN HAN.
PowerLens is licensed under the GNU Affero General Public License v3.0 only
(AGPL-3.0-only). See LICENSE.