It's never a good idea to guess with measurements, that's what measuring tools are for. No need to look for a power outlet, since it runs on batteries. Just get at it!
From Amazon
Bosch Professional Cross line Laser GCL 2-15 (red Laser, Interior, with Plumb Points, Working Range: 15 m, 3 x AA Batteries, RM 1 Rotating Mount, Laser Target Plate, Protective Bag)
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