Drywall thickness for placing over ceiling drywall
Ceilings require 5/8&quot; or 1/2&quot; no-sag for 24&quot; joist span. If you're able to screw it at 16&quot; intervals or use adhesive between joists you could use standard 1/2&quot;. I wouldn't use 3/8&quot; unless you have backing at 12&quot; intervals or run adhesive between joists. 1/4&quot; just isn't appropriate for a ceiling.
Update: For 16&quot; joist span I'd use 1/2&quot; or run a bead of construction adhesive between joists and use 3/8&quot;. I wouldn't trust 3/8&quot; to not sag over 16&quot;, and 1/4&quot; almost certainly will. Note that it can be difficult to prevent screw punch-through with 3/8&quot; sheets. Set your screw gun's depth accurately.
Personally I'd be spending a few bucks more for lightweight 1/2&quot; and not worry about glue or sagging. This will reduce the chance of over-stressing your ceiling framing, also.