How long can you extend a 12V DC cable?

[MisterBoy]

My IP CCTV comes with a fairly short power lead that's not much use. I can see extensions up to 15m on Amazon but wondered how long you can reasonably extend a cable before you run into problems?

 

[secureiam]

Depends on the quality of cable, it can be calculated.

Voltage Drop Calculator | 12-volt planet (12voltplanet.co.uk)

if its IP, then the ethernet cable can be used if NVR as POE.

 

[MisterBoy]

I'm going to use the camera via WiFi but it does support ethernet, I didn't consider checking for PoE. Not sure if it's preferable(?) but you get cable that feels a lot less feeble.