You can try datavalidationallowcustom and use

=A3<"X"

that will prevent anyone typing anything in A4 (but not pasting)
if A3 holds "X"


Regards,

Peo Sjoblom

"JoeMNY" wrote:

Greetings,

I'm sure this is possible but I can't figure it out. How can I disable a
cell based on input in another cell. Example:

A1=Powered
A2=Glider
A3=
A4=

If an "X" is placed in A3, I want A4 disabled (locked).

TIA