Laser printers are separated by generation.
It was the first generation that took 1kW when bringing the fuser up to standby temp.
Modern toners (at least the color toners) melt at a lower temperature, which means the fuser design now has a lower mass, and also a slightly different implementation (quartz tube with heater inside).
The number now should be less than the "old 1kW" number.
Example: Samsung ML-1670 (Samsung Laser division now owned by HP...)
Power consumption (printing) 270 W Power consumption (standby) 40 W Power save mode <2.8 W Power off mode <0.45 W AC input voltage 220 - 240 V AC input frequency 50/60 Hz
Since nice cheap gutless UPS are available, there will still be a temptation to run too high a load on them. You should never buy a UPS from the "first tier" which is the cheap and cheerful tier. We tried that at work... The failure rate from new, was around 10% on those. None of the failures were destructive (of ~100 units tested). The quality issues should have been sorted at their factory.
*******A Kill-O-Watt meter measures Watts, VA, and PF. And has taken all the guesswork out of picking a UPS.
Connect all the loads to the Kill-O-Watt. Then use the three numbers that result, to pick the UPS.
On the computer, run Prime95, as a means of getting a representative load. At the same time, send a print to your Samsung laser printer. Now, look at the Kill-O-Watt display, to see what your "estimated worst case" is.
Before the Kill-O-Watt meter existed, it was a lot harder for ordinary people to size these things.
Even incandescent light bulbs can be deceiving. When cold, a 60W lightbulb draws 120W at startup. If you had 5 incandescent light bulbs, each switched on individually, you'd need 4*60W + 120W or 360W max (at the moment you're switching on the fifth lightbulb).
If all bulbs were switched via a common lightswitch, the power (worst case) would be 5*120W or 600W max. It depends on whether a UPS has a "hair trigger", as to whether it drops out the instant a light bulb load appears like that (whether a 600W load for 5-10 mains cycles would be enough to trip it).
ATX power supplies (desktop PC) have terrible characteristics. They can draw 40A for a few mains cycles. But only occasionally does this cause a problem. Anandtech evaluated one ATX PSU, a device rated for >1kW DC output, and every time they turned it on at the back, it tripped their lab breaker. Which is surely an achievement (as to trip a breaker instantly, takes around 5x the breaker rating).
The transient behavior of loads, and the cheesiness of some UPS designs, are confounding issues.
And on electric motors, the stall current or locked rotor current rating, can be 10x the operational value. A 2HP motor could draw 20HP at startup (15kW). And that causes indigestion for a lot of solutions. A 2HP motor is the largest motor I've seen in a domestic situation (YMMV). I'm sure many here will have bigger kit than that. That's why even fractional HP motors aren't a good fit for UPS.
*******For the comedic value...
At the moment, when the A/C starts up, the Powerwalls do not enter a fault state, but my house blacks out for a quarter second (the lights literally go off) and all the electronics reboot. "
An easy way to do reboots.
Paul