384 well plate dimensions
The same footprint as 96, four times the wells. The numbers your readers and handlers are built around.
A 384 well plate is a 96 well plate footprint with each well quartered. Same outside dimensions, same instruments, wells on a 4.5 mm grid instead of 9 mm. Height and well depth are what change between 384 plates.
The footprint never changes
The ANSI/SLAS standard footprint is 127.76 mm long by 85.48 mm wide, identical to a 96 well plate. That is the entire point of the format: quadruple the well count without changing a single instrument. If a 384 plate does not meet the footprint, it will not run on automation.
Well pitch and the A1 corner
Wells sit on a 4.5 mm grid, 16 rows (A to P) by 24 columns. Each 96 well position becomes a quadrant of four 384 wells, which is how four 96 plates consolidate into one 384. Well A1 is the indexing corner, marked on the drawing; instruments and software count from it.
Height is the variable
Assay 384 plates are low profile, and 384 deep well plates stand taller for storage volume. Height decides stacker capacity and whether a sealer or clamp closes over the plate. When a 384 plate almost fits a handler, check the full stack height, plate plus seal or lid, before blaming the footprint.
Related guides
Common questions
Are 384 well plates the same size as 96 well plates?
The footprint is identical, 127.76 by 85.48 mm. The wells are smaller and closer together (4.5 mm pitch instead of 9 mm), and total height varies by type.
What is the distance between wells on a 384 well plate?
4.5 mm center to center in both directions, exactly half the 9 mm pitch of a 96 well plate.