24 well plate dimensions
The standard footprint, a well layout the standard does not fix. The numbers your readers and handlers are built around.
A 24 well plate shares the microplate footprint with every other format, which is why it runs on the same readers and shakers. What it does not share is a standardized well layout: the ANSI/SLAS standards fix well positions only for 96, 384, and 1,536 well plates, so 24 well positions follow a de facto 18 mm grid that nearly every maker uses, and a few culture plates depart from.
The footprint never changes
The ANSI/SLAS standard footprint is 127.76 mm long by 85.48 mm wide. Plate readers, washers, shakers, seals, and liquid handlers are all built to it. If a plate is sold as a standard 24 well plate and does not meet the footprint, it will not run on automation, whatever the product page says.
Well positions are the de facto part
The ANSI/SLAS well position standard covers 96, 384, and 1,536 well plates only. The 24 well layout follows the same scaling logic, each 96 well cell doubled, which puts wells on an 18 mm grid, and most makers, including the deep well and filter plates in this format, follow it. Some cell culture plates sit slightly wider, around 19.5 mm between wells, because they descend from culture dish tooling rather than microplate tooling. The practical consequence: before hard-coding a handler offset or trusting a reader layout file, read the well positions off the drawing for the specific plate. A1's position is also maker-defined here, commonly near 18.9 mm from the left edge and 15.8 mm from the top on plates that follow the de facto grid.
Height is the variable
Total height runs from about 20 mm for a culture plate with its lid to about 44 mm for a 10 mL deep well plate. Height decides stacker and shelf capacity, whether a clamp or sealer closes over the plate, and how much headroom a handler needs. When a plate almost fits, height is usually the dimension to check, and the full stack height, plate plus lid or seal, is the number that matters.
Related guides
Common questions
Do all 24 well plates have the same dimensions?
The footprint is standard at 127.76 by 85.48 mm. Well positions are not fixed by the ANSI/SLAS standard for this format: most plates follow a de facto 18 mm grid, but some culture plates are wider spaced, and height runs from about 20 mm to about 44 mm by type. Read the drawing for the specific plate before a regulated run.
What is the distance between wells on a 24 well plate?
18 mm center to center in both directions on plates that follow the de facto grid, which is most deep well, filter, and reader-oriented plates. Some cell culture plates use a wider spacing near 19.5 mm. Unlike the 9 mm pitch of a 96 well plate, the 24 well spacing is a convention, not a standard, so verify it on the plate specification.
What is the diameter of a well in a 24 well plate?
A round culture well is about 15.6 mm across, which is where its roughly 1.9 cm2 growth area comes from. Square deep well plates measure about 17 mm across the top of each well. Diameter drives growth area, imaging field, and how a seal or cap sits, so read the exact figure off the drawing for the specific plate.
How deep are the wells in a 24 well plate?
Culture wells are shallow, in a plate about 20 mm tall with its lid, holding about 3.5 mL to the brim. A 10 mL deep well plate stands about 44 mm tall, with wells roughly 42 mm deep. Depth sets the working volume and how far a tip travels, so it is worth reading off the drawing rather than inferring it from plate height.