Petri Dishes 100×15 mm: What Should a Canadian Lab Check Before Ordering?
A 100 × 15 mm petri dish is the least complicated line on a laboratory order, which is why it gets reordered without a second look. That shortcut is also how a bench ends up with plates that will not sit in the incubator rack, or a fill depth that no longer matches the method.
The dish is a controlled consumable, not packaging: its diameter sets how much medium you pour, its wall height sets how a stack behaves in the incubator, and its sterility claim is what keeps a negative control negative.
What do the numbers 100 × 15 mm actually describe?
A dish size is written as nominal outside diameter × wall height in millimetres. On a 100 × 15 mm dish the 100 is the outside diameter of the base and the 15 is the height of the base wall, so the lid sits over a 15 mm rim. The figure is nominal, not a tolerance: two suppliers can both ship a 100 × 15 mm dish and still differ by a millimetre, which matters when a plate has to turn on a spreader turntable or stack in a fixed rack.
Which dish size does a routine culture bench use?
Volume follows area, and area grows with the square of the diameter, so a small step up in diameter is a larger step up in medium.
| Nominal size | Fill at a 4 mm depth | Where it is used |
|---|---|---|
| 60 × 15 mm | about 9 mL | small-volume work and teaching benches |
| 90 × 15 mm | about 20 mL | routine culture and the default laboratory format |
| 100 × 15 mm | about 25 mL | larger surface for counts and automated counters |
A 90 mm plate holds about 20 mL at a 4 mm depth in published pour-plate work. The 100 mm dish has roughly 23 per cent more surface, so the same depth needs about 25 mL, and a shallower pour changes how colonies grow and how an antimicrobial diffuses.
Which material should a Canadian lab order, polystyrene or glass?
Single-use polystyrene is the default on a clinical bench: it is optically clear, it arrives sterile and ready to pour, and it is discarded after use, so no wash and no re-sterilisation step is added. Glass dishes can be reused and tolerate higher temperatures, but they depend on a validated wash and sterilisation cycle and they break. For routine culture, polystyrene carries less process risk because the sterility assurance comes from the supplier rather than from the laboratory's own reprocessing.
What should be confirmed about sterility and packaging before ordering?
- The sterilisation method and the sterility assurance level the supplier states
- Whether dishes ship sleeved and shrink-wrapped, or loose in a case
- The lot number and expiry printed on the case
A sterile plate that arrives in a torn sleeve is no longer sterile.
How does a used plate leave a Canadian lab?
A plate stops being a consumable the moment it is inoculated. Ontario's Guideline C-4 sets out the categories of biomedical waste that apply in the province, and used cultures and the plates that hold them fall into the microbiology laboratory waste stream, which is contained and labelled rather than placed in general waste.
Ordering for a clinic, lab or care home? Wholesale and multi-site ordering covers case pricing and account setup, and the B2B wholesale collection lists the lines stocked for institutional buyers.
A culture bench usually restocks 100 × 15 mm sterile polystyrene dishes by the case, next to 15 mL centrifuge tubes for sample preparation and 95 kPa specimen transport bags, with the wider list held in laboratory consumables.
References
- Guideline C-4: The Management of Biomedical Waste in Ontario (checked 29 September 2026)
- Criteria for Acceptance of Specimens, Public Health Ontario (checked 29 September 2026)
- The relationship between agar thickness and antimicrobial susceptibility testing, PMC5671438 (checked 29 September 2026)
- ISO 11133:2014 — preparation and performance testing of culture media (checked 29 September 2026)
Related Reading
- Sterile Petri Dishes in a Clinic Lab: Handling, Labelling and Incubation Basics
- Agar Petri Dishes: Agar Types, Prepared Plates and Storage
- Vented vs Non-Vented Petri Dishes for Clinic Labs
Frequently Asked Questions
What size is a 100 × 15 mm petri dish?
A nominal outside base diameter of 100 mm and a base wall height of 15 mm. The figure is nominal, so one supplier's dish can differ by about a millimetre.
How much agar goes into a 100 mm petri dish?
About 25 mL for a 4 mm depth. A 100 mm dish has roughly 23 per cent more surface than a 90 mm dish at the same depth.
Do petri dishes arrive sterile?
Sterile dishes are supplied sterile, with the method and sterility assurance level stated by the supplier. The claim holds only while the sleeve is intact.
Can a Canadian lab reuse glass petri dishes?
They can be reused, but reuse moves sterility assurance onto the lab and needs a validated wash and sterilisation cycle. Single-use polystyrene removes that step.
How should used petri dishes be disposed of in a Canadian lab?
As microbiology laboratory waste. Ontario's Guideline C-4 covers used cultures and the plates that carry them; other provinces set their own rules.
Last updated: September 2026. CliniEco Medical is a licensed medical device establishment (MDEL #35334).
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