What measure of manna were the Israelites told to gather for each person?

Answer: An omer

Moses told them to take an omer for each person in their tent; an omer is a tenth of an ephah.

“This is what the LORD has commanded: ‘Each one is to gather as much as he needs. You may take an omer for each person in your tent.’” (Now an omer is a tenth of an ephah.)”— Exodus 16:16, 16:36 (BSB)