Depends on the laptop, my new Thinkpad (T470P) has a processor with a TDP of 45W (limited to 35W) plus the screen. Theoretically if I pegged it out with the sc

Depends on the laptop, my new Thinkpad (T470P) has a processor with a TDP of 45W (limited to 35W) plus the screen. Theoretically if I pegged it out with the screen on max brightness I'd get about 90 minutes out the battery (which is about what linux estimated running stress-ng) in reality depending on what I'm doing I get 5-6 hours and if it's light surfing on an evening over 7. Currently it's saying 3 hours 58 minutes @33% charge, I'm actually surprised how long it lasts given I didn't expect it to but looking at powertop it spends a good chunk of it's time running at about half it's top clock rate and it rarely bursts. Though to be fair I didn't buy this laptop for it's battery life (I can swap those out if needed) or weight (not that it's excessive) but because it sat on a local maxima for what I wanted (fast quad core with HT, relatively light, relatively good battery life). The GF's little Asus regularly goes over 10 hours with her using it for the usual net stuff and it's got a tiny battery, it's a cracking little machine but Intellij would wreck it.