What size screws go in the back of a tv for a wall mount

Screw size will vary depending on the VESA size of your television. M4 screws are typically used with smaller sizes (under 200 mm). M6 screws are the common choice for 200x200 televisions and M8 screws are for even larger screens.

M8 × 1.25mm if you are talking about the feet on the bottom. Same metric bolt / screw just longer for the wall mount bracket. The thread depth is 20-22mm + the thickness Of the bracket and washer.

WARNING! If you use screws other than those specifically supplied with the wall mount bracket for your TV, the TV may fall and cause physical injury to someone or damage to the TV. The wall mount hole pattern on some models may conform to the VESA Mount Standard, but the number and depth of the screw holes do not.

Don't forget TV mount screws are essentially meant to fasten your TV screen to the bracket. So, they are expected to be universal. But here's the caveat: your TV mount screws can only be universal if they come in the same VESA size.