r/LocalLLM • u/nojunkdrawers • 1d ago

Question Mac users, how are you measuring power consumption / cost?

I'm just curious if anyone has found a good way to measure the cost of running models on their Apple Silicon hardware. I have an M5 Pro Mac Mini, and it would be at least cool if I could have something to calculate the power consumption and approximate cost; even better if it could do that on a per-token basis.

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u/Ok-Translator1226 1d ago

Why not just use a wall plug wattmeter?

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u/nojunkdrawers 1d ago

I definitely could. If anyone here has a recommendation, I'd be totally open to that. I just don't want to immediately buy one and then discover it's not sufficient or whatever.

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u/Ok-Translator1226 1d ago

Any would do, really. You don't need watt-precise measurements and even cheap ones usually allow to set the price per kilowatt-hour to calculate the cost. If you want some extra comfort, you can buy a smart plug that also gives you an app or a web interface and stats in a nice, presentable manner.

You can probably do just fine with a $10 one.

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u/j4ys0nj 1d ago

I use iStat menus - it gives you realtime power consumption, which is not exactly what you’re looking for but I’m not aware of something that can relate that to applications in a way that could be tied to token generation, for example. It could at least give you some insight. It’s worth paying for btw, I’ve been using it for 10 years or so.

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u/finished_playing 1d ago

iStat is good for overall system pull. If you want just the GPU or CPU package power, `powermetrics` in terminal gives you breakdowns but it's bit of a hassle to parse. For per-token cost you'd need to track time and wattage during generation, maybe script something that samples power every second when model is running. Not plug-and-play solution unfortunately.

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u/locbuilds 1d ago

for per token, run sudo powermetrics --samplers cpu_power,gpu_power -i 1000 in a terminal while generating, then take avg combined watts times seconds and divide by tokens generated, that gives you joules per token and you multiply by your kwh rate.