Mac battery guides

Updated 6 November 2026 · Who measures this.

Battery health tells you how big the tank is. WattMate shows what is emptying it. Every number we measured names the Mac it came from, with the method and its limits stated; figures from others say whose they are. Where something can't be measured honestly, the page says so instead of estimating.

Where did my battery go?

The battery is draining fast. Which case is it? 4 different problems share that one symptom, and only 1 of them is the battery. Each has a tell you can check in a minute. Which app is using my battery, in watts? Every app as one row in watts, helpers folded in, measured by the kernel's own per-process energy counter. What the rest of the power is, and when the list stays empty. macOS says an app is "Using Significant Energy" The menu names the app and never a number, and Apple publishes no threshold. Why Activity Monitor shows nothing by the time you open it, measured. How many watts is my MacBook using? There is no single figure, and we can show why: 436 measured windows spanning 6.74 W to 59.73 W, and 2 Macs whose averages sat 3 times apart. Does quitting apps actually save battery? Mostly no: macOS handles idle apps well. But when one app is the bulk of the use, quitting it is worth real minutes. How to tell which case you're in. The percentage sits still, then drops 2 at once Not a glitch: a whole number laid over a charge counter that moves both ways. 3,100 measured steps, 218 of them backwards, and the largest hid 166 mAh.

What each app costs

Which apps drain a Mac's battery, measured in watts Chrome, Xcode, Claude, Telegram, Spotify and Slack side by side. Over 484 hours on 2 Macs, apps took 14 to 26% of the battery, and the screen and the system took the rest. How much battery does Chrome use? 4 to 10% of the battery over 2 months. Quitting it was worth 24 minutes on one Mac and 142 on the other. How much battery does Claude use? From under 1% to about 7% of the battery over 2 months, depending on how you use it. The desktop app draws steadily, and Claude Code stays quiet until something runs under it. How much battery does Xcode use? 44 Wh, nearly 3 times Chrome on the same Mac. A peak of 48.5 W and 166 processes at once. Idle is cheap; builds are the entire bill. How much battery does Slack use? 0.82% of the battery over 138 hours. The typical draw stays near zero, and the busy moments make the total. How much battery does Telegram use? 0.45% of the battery over 138 hours. Its typical draw fell from 0.26 W to 0.01 W. How much battery does Spotify use? Very little: 0.42% of the battery over 138 hours, 0.02 to 0.19 W typical. The app you notice and the app that costs you are rarely the same one. Does AI drain your Mac battery? ChatGPT, coding agents and a local model, measured on the whole Mac on 5 Macs, with the data published. Why 2 short messages can use so much of an AI agent's limit Back in a big session after the cache expired, Claude Code wrote the whole conversation again. A new session on the same task wrote about 8% of that.

Battery health

Health says 96% but it only lasts 4 hours Health measures the size of the tank; runtime is capacity divided by the power going out. The watts-to-hours table, and the 3 cases where the battery really is at fault. Battery health vs cycle count: which one matters? Cycles say how much life the pack has spent, health how much it holds now. One Mac at 538 of its 1,000 rated cycles, capacity already at 82.22%. System Settings says 87%, my battery app says 85% The controller publishes 2 capacity figures, a smoothed one and a raw one, and software picks. Which is which, what each is good for, and why the number wanders during the day. Checking a used MacBook's battery before you buy A seller states a cycle count and a health percentage. Check the pair against 1,539 other real batteries at similar mileage instead of a made-up threshold.

Overnight and sleep

Why does my Mac lose battery in sleep? About 0.3 percentage points an hour is normal. Above that, something is waking it. And the arithmetic to tell one from the other. Who wakes your Mac at night? Mostly macOS itself. Which services woke the Mac, and why the answer differs from one Mac to the next.

Charging and power

The Mac stopped charging at 80%. Why? The charge controller keeps a record of why it is not charging, and macOS does not show it. One command reads it and says in words whether a limit is holding the charge. Mac says "Charging On Hold" It's deliberate, not broken. What each status means, how to charge to full now, and the one case no status covers. Where the adapter's watts go Plugged in, the question becomes whether the adapter is keeping up. What it delivers, what the Mac uses and what reaches the battery. Charging an iPhone from a sleeping MacBook One measured night: the Mac drew 18.9 W instead of the 0.8 W it drew the rest of that night, and 15.1 Wh left the battery in 48 minutes.

Updates

Battery worse after the macOS 27 update? The first days are partly expected while the system rebuilds its indexes. How to tell settling from an app that broke, and what the same chip did on 2 versions of macOS.

Choosing an app

The best Mac battery apps, sorted by the job 4 different jobs wear the name "battery app". Honest picks for each, including the 3 where the answer isn't ours. Mac battery app alternatives: what actually changes Every comparison in one place, including the ones where the honest answer is to stay where you are.

Head to head: WattMate and Juicy · WattMate and AlDente · WattMate and coconutBattery

Read the numbers yourself

Mac battery tools 4 Terminal commands that print what macOS keeps to itself: both capacity figures your Mac stores, live power draw in watts, the lifetime counters inside the battery controller, and whether a limit is holding the charge. No password, nothing installed.

How the measuring works

How we count The instruments, the arithmetic and every limitation we know about, including the numbers we refuse to print because they can't be measured honestly. How WattMate's numbers are checked On 6 Macs: the app against each Mac's own power sensor, and that sensor against a USB-C meter not made by Apple. Rules and scripts were published before the first counted run. Why about half of a Mac's CPU energy has no owner The per-process energy counter dies with the process, and the kernel's own work has no process at all. Written for people building the same kind of tool.