What is a microplate?
The general idea, explained from the 24 well end of the range, where the wells are big enough to see into and the trade-offs are about room, not density.
A microplate (also called a microtiter plate or a multiwell plate) is a flat, usually rectangular plastic plate holding a grid of small, separate wells, each one a miniature test tube. One plate therefore carries dozens of independent samples, reactions, or cell cultures, all on the same standard footprint, 127.76 mm by 85.48 mm under the ANSI/SLAS standards, so the plate moves between pipettes, incubators, centrifuges, and readers as a single unit.
This site covers the 24 well member of the family: 4 rows by 6 columns of wells on that footprint. The general guide to what a microplate is lives on the 96 well plate guide; this page answers the same question from the large-well end.
Why 24 wells exist
The microplate family scales in both directions from 96. Divide the footprint finer and you get 384, for screening density. Divide it coarser and you get 48, 24, 12, and 6, for room: each step up trades well count for growth area and volume per well. 24 is the rung where a well stops being a miniature and becomes a small culture vessel in its own right: about 1.9 cm2 of growth area, a milliliter of medium, enough cells to image, harvest, or assay without pooling wells. Work that starts in flasks and needs parallels moves down to 24; work that starts at 96 and runs out of room moves up to it.
Who uses 24 well plates, and for what
- Cell culture: primary cells, transfection, differentiation, and stem cell work that needs area and medium depth per well.
- Imaging assays: wells wide enough, about 15.6 mm, to image whole fields under a microscope.
- Sample preparation: filtration and extraction at the 10 to 15 mL scale in 24 well filter plates.
- Storage and processing: deep well plates holding 10 mL per well for samples that do not fit the 2 mL world of 96.
- Scale-up and scale-down studies: a middle step between flask culture and 96 well screens, where conditions are proven before miniaturizing.
- Forensic and testing labs: extraction, incubation, and preliminary screening of evidence samples at milliliter scale, in sterile, DNase/RNase-free plates where the sample cannot be replaced.
What changes at 24
Three things, all of them consequences of big wells. The work goes back to hands: 24 well plates are filled well by well with single channel pipettes or repeat dispensers, because the multichannel tools of the 96 world do not map onto the wider spacing. Each well carries more value: more cells, more medium, more days of culture per well, so a single failure costs more and contamination control matters more, not less, than at 96. The instruments stay the same: the footprint is the family standard, so readers, washers, shakers, and centrifuge carriers built for microplates take a 24 well plate without adapters. The buying guide works through choosing within the format.
Microplate words, sorted
Microplate, microtiter plate, microwell plate, multiwell plate: four names for the same object, used interchangeably in catalogs and papers. A 24 plate: a microplate with 24 wells, named by its count. A plate reader: the instrument that measures the plate, bought separately and matched to the plate format. Well address: the row letter and column number of a well, A1 to D6 on a 24 plate, the coordinate every result hangs on. The full plain-language treatment, including well shapes, colors, materials, and handling pitfalls, is the what is a microplate page on the 96 well guide.
The 24 well format in numbers
| Measure | 24 well format |
|---|---|
| Rows x columns | 4 x 6 |
| Well spacing | 18 mm de facto (positions for 24 are not set by ANSI/SLAS) |
| Footprint | 127.76 x 85.48 mm (ANSI/SLAS), same as 96 well |
| Working volume | 0.5 to 1 mL (culture), up to 10 mL (deep well) |
| Total (brim) volume | About 3.5 mL per culture well, 10 mL per deep well |
| Growth area per well | About 1.9 cm2 |
Volumes and growth areas are working ranges for common plates; confirm the exact figure on the specific plate before a regulated run.
Related guides
Common questions
Is a 24 well plate a microplate?
Yes. Microplate is the family name for every format on the standard footprint, from 6 wells to 1,536. A 24 well plate is the large-well member most culture labs use: 4 rows by 6 columns, with wells big enough to hold a milliliter of medium or 10 mL in deep well form.
Why do 24 well plates exist?
To give each well room. Dividing the standard footprint into only 24 wells makes each one about six times the growth area of a 96 well, which is what primary culture, transfection, imaging, and milliliter-scale sample prep need and what denser formats cannot offer.
How are wells identified on a 24 well plate?
By row letter and column number: 4 rows, A to D, and 6 columns, 1 to 6, so every well has an address such as D6, the last well. The notched or labeled corner marks A1, the first.
Can a plate reader read a 24 well plate?
Yes. The footprint is the universal standard, and plate readers, washers, and shakers that take microplates take the 24 well format. Well positions for 24 are a de facto layout rather than an ANSI-fixed one, so readers use their 24 well definition; check that yours carries one before the first run.
Can you use a 24 well plate for screening?
For small, precious screens, yes: 24 conditions per plate with enough material per well for follow-up assays from the same well. For library-scale screening, no: the well count is the limit, and that work belongs at 96 or 384. 24 is where screens go to be confirmed and understood, not discovered.