External Display Limitations?


I bought a 2015 MacBook Pro 15" and want to use it in clamshell mode most of the time with an external monitor. I don't want to buy a thunderbolt monitor. I already have a TV with HDMI. If I use HDMI, is the fact that I'm using HDMI the limiting factor for the max resolution or can I still drive a monitor over HDMI up to the max resolution of the TV?


Supports an HDMI-compatible device, including 4K, while using one Thunderbolt display or support for two Thunderbolt displays
of course...
more info here

You didn't tell us the max resolution of your present TV.
Make sure that your HDMI cable supports at least HDMI 1.4. If your cable is an older HDMI cable, you might need to replace for best support, particularly if you have a 4K TV.
You may be OK with that if you have purchased a new cable within the last couple of years.