12 well plate dimensions
One footprint, a 26 mm grid, and wells the size of small dishes: the numbers that decide whether a plate fits your stage, shaker, and inserts.
Every 12 well plate shares the ANSI/SLAS footprint, 127.76 by 85.48 mm, and the 26 mm well grid. What varies is well diameter, plate height, and the insert geometry, and those are the dimensions that decide fit.
The grid and the footprint
Wells sit on a 26 mm pitch in 3 rows by 4 columns. The A1 well center sits in the plate's corner region defined by the ANSI/SLAS standards, offset from the two edges so stages and readers register every plate the same way. The pitch is wide enough that standard pipettes work well by well without spacing adjustment, and the plate drops into the same microscope stage inserts and reader carriers as every other format.
Well sizes by kind
Culture wells are round, about 22 mm across, giving the 3.8 cm2 growth area and the 1 to 2 mL working volume. Insert wells carry the same well with a ledge or suspension geometry for the insert basket; the insert's own diameter and membrane sit inside that envelope. Deep well 12 plates use square wells in the 5 mL class, several times deeper than the culture well.
Heights
A 12 well culture plate stands about 17 to 20 mm tall with its lid, the shallow profile shared across culture formats. Insert plates stand taller by the insert's rim, and deep well versions taller still. Catalogs quote height inconsistently (with lid, without, to the skirt), so measure the physical plate against any close clearance, such as a shaker clamp or a stacked incubator shelf.
The fit checks that matter
- Microscope: the standard footprint fits stage inserts; check instead that the well bottom and your objective's working distance agree, especially for glass bottom plates.
- Inserts: the insert system is plate specific; check the maker's pairing, not just the well count.
- Shaker: clamp reach against plate height for deep well versions.
- Handler: plate definition in the software for the deep well format.
Related guides
Common questions
What is the well spacing of a 12 well plate?
26 mm center to center, in both directions, on a 3 by 4 grid. It is the ANSI/SLAS defined pitch for the format.
Is a 12 well plate the same size as a 96 well plate?
Outside, yes: both are 127.76 by 85.48 mm. Inside, no: the 12 has wells about 22 mm across at 26 mm pitch, each with twelve times the growth area of a 96 well.
How deep is a 12 well?
A culture well is a shallow dish, roughly 17 mm of plate height overall, worked at 1 to 2 mL. Deep well 12 plates run much deeper, sized to their 5 mL class volumes. Well depth, not plate height, is the number handler aspirate heights are programmed from.
Where is the A1 well on a 12 well plate?
In the corner the standards define, offset from the top and left edges of the footprint so instruments register consistently. Plates mark A1 with the row and column labels molded along the edges; the top left well when the labels read upright is A1.