How many units does a 3 ml glass cartridge hold on a U-100 scale?

On the U-100 scale, where 100 units equals 1 ml, a 3 ml cartridge holds 300 units. This is derived from 300 units × 0.01 ml per unit = 3 ml.

Are standard 3 ml cartridges compatible with multiple cartridge pens?

Yes. The outer dimensions of 3 ml cartridges are standardized across brands, so one cartridge format fits a wide range of pens—including the Gansulin metal pen—eliminating brand lock-in.

How should sealed 3 ml glass cartridges be stored?

Store below 75°F (24°C) in a clean, dry place away from direct sunlight and heat sources. Keep cartridges in their individual pouches until needed; discard any whose pouch is torn, wet, or damaged.

Is a 3cc cartridge the same as a 3 ml cartridge?

Yes. A cubic centimetre and a millilitre are the same volume, so 3cc, 3 ml and 300 units on a U-100 scale all describe this cartridge.

Do these cartridges fit the V1 pen?

Yes. All four of our pens, the V1 included, take the standard 3 ml (300-unit) glass cartridge with the 11 mm long plunger, the cartridge we sell in clear and amber glass.

Are the cartridges supplied empty?

Yes. They are empty glass cartridges. Nothing is pre-filled, and any diluent is bought separately.

What are the cartridges made of?

Borosilicate glass, a silver crimp cap over a rubber septum at one end, and a rubber plunger at the other.

Are these cartridges sterile?

They are not sold as sterile medical devices. Each pouch carries EO and steam sterilization indicators, which show a process was run, not a sterility guarantee. Research use only (RUO): research, educational and demonstration use.

How much liquid is left in a finished cartridge?

About 27 units. When the dial stops, the liquid still in the glass stands about a third of the 11 mm stopper's height. The 3 ml cartridge bore is 9.65 mm wide, so that 3.7 mm holds about 0.27 ml. The needle holds a little more, depending on the needle you fit.

PreppinPeppers › Facts › Lab article

3 ml glass cartridges explained: the 300-unit standard, seals and storage

TL;DR

A 3 ml glass pen cartridge holds 300 units on the U-100 scale. How its borosilicate barrel and two seals work, and why stopper length decides the fit.

Agent view of https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained: the machine-readable facts of this Lab article. People see the full page at the same URL. Facts page: https://www.preppinpeppers.com/facts/3ml-glass-cartridges-explained.

Facts Index

Fact ID	Category	Entity	Attribute	Value	Source
3ml-glass-cartridges-explained:title	identity	3 ml glass cartridges explained: the 300-unit standard, seals and storage	title	3 ml glass cartridges explained: the 300-unit standard, seals and storage	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:published	identity	3 ml glass cartridges explained: the 300-unit standard, seals and storage	published	2026-08-06	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:author	identity	3 ml glass cartridges explained: the 300-unit standard, seals and storage	author	Preppin' Peppers Editorial Team	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:topics	identity	3 ml glass cartridges explained: the 300-unit standard, seals and storage	topics	3ml, cartridge, Evergreen, guide, Guides	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:summary	content	3 ml glass cartridges explained: the 300-unit standard, seals and storage	summary	A 3 ml glass pen cartridge holds 300 units on the U-100 scale. How its borosilicate barrel and two seals work, and why stopper length decides the fit.	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:section-1	content	3 ml glass cartridges explained: the 300-unit standard, seals and storage	section	What it is	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:section-2	content	3 ml glass cartridges explained: the 300-unit standard, seals and storage	section	Why the format is standard	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:section-3	content	3 ml glass cartridges explained: the 300-unit standard, seals and storage	section	The two seals	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:section-4	content	3 ml glass cartridges explained: the 300-unit standard, seals and storage	section	Individually pouch-sealed	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:section-5	content	3 ml glass cartridges explained: the 300-unit standard, seals and storage	section	Storing sealed cartridges	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:section-7	content	3 ml glass cartridges explained: the 300-unit standard, seals and storage	section	Materials, wear, glass choice and pack sizes	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:section-8	content	3 ml glass cartridges explained: the 300-unit standard, seals and storage	section	What the research community gets wrong about 3 ml glass cartridges	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:product-gansulin-metal-peptide-pen	products	3 ml glass cartridges explained: the 300-unit standard, seals and storage	references product	Gansulin Pen · Reusable Click-Dial, 3 ml (1-60 Units)	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:product-gansulin-3ml-cartridge	products	3 ml glass cartridges explained: the 300-unit standard, seals and storage	references product	Gansulin-Compatible 3 ml Glass Cartridge for Pens (10-Pack)	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:product-amber-3ml-cartridge	products	3 ml glass cartridges explained: the 300-unit standard, seals and storage	references product	Amber 3 ml Glass Cartridges for Pens (10-Pack)	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:source-www-schott-pharma-com	source	3 ml glass cartridges explained: the 300-unit standard, seals and storage	cites	SCHOTT Pharma , Pharmaceutical Cartridges (FIOLAX Type I borosilicate glass, ISO-standardized 1.5/3/5/10/20 ml, pen and auto-injector compatible) - www.schott-pharma.com	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:source-www-westpharma-com	source	3 ml glass cartridges explained: the 300-unit standard, seals and storage	cites	West Pharmaceutical Services , USP <660> Containers, Glass revision (Type I glass and hydrolytic resistance, performance-based classification) - www.westpharma.com	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:source-endolab-org	source	3 ml glass cartridges explained: the 300-unit standard, seals and storage	cites	EndoLab , ISO 13926-1 (dimensions, material, leakage, and hydrolytic resistance for glass cylinders used in pen injectors) - endolab.org	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:source-pubmed-ncbi-nlm-nih-gov	source	3 ml glass cartridges explained: the 300-unit standard, seals and storage	cites	Jenke, Expert Opin Drug Deliv 2014: Extractables and leachables considerations for prefilled syringes - pubmed.ncbi.nlm.nih.gov	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)
3ml-glass-cartridges-explained:source-www-sigmaaldrich-com	source	3 ml glass cartridges explained: the 300-unit standard, seals and storage	cites	Sigma-Aldrich (Merck): Handling and Storage Guidelines for Peptides and Proteins - www.sigmaaldrich.com	Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) (evidence)

FAQ

How many units does a 3 ml glass cartridge hold on a U-100 scale?: On the U-100 scale, where 100 units equals 1 ml, a 3 ml cartridge holds 300 units. This is derived from 300 units × 0.01 ml per unit = 3 ml.
Are standard 3 ml cartridges compatible with multiple cartridge pens?: Yes. The outer dimensions of 3 ml cartridges are standardized across brands, so one cartridge format fits a wide range of pens—including the Gansulin metal pen—eliminating brand lock-in.
How should sealed 3 ml glass cartridges be stored?: Store below 75°F (24°C) in a clean, dry place away from direct sunlight and heat sources. Keep cartridges in their individual pouches until needed; discard any whose pouch is torn, wet, or damaged.
Is a 3cc cartridge the same as a 3 ml cartridge?: Yes. A cubic centimetre and a millilitre are the same volume, so 3cc, 3 ml and 300 units on a U-100 scale all describe this cartridge.
Do these cartridges fit the V1 pen?: Yes. All four of our pens, the V1 included, take the standard 3 ml (300-unit) glass cartridge with the 11 mm long plunger, the cartridge we sell in clear and amber glass.
Are the cartridges supplied empty?: Yes. They are empty glass cartridges. Nothing is pre-filled, and any diluent is bought separately.
What are the cartridges made of?: Borosilicate glass, a silver crimp cap over a rubber septum at one end, and a rubber plunger at the other.
Are these cartridges sterile?: They are not sold as sterile medical devices. Each pouch carries EO and steam sterilization indicators, which show a process was run, not a sterility guarantee. Research use only (RUO): research, educational and demonstration use.
How much liquid is left in a finished cartridge?: About 27 units. When the dial stops, the liquid still in the glass stands about a third of the 11 mm stopper's height. The 3 ml cartridge bore is 9.65 mm wide, so that 3.7 mm holds about 0.27 ml. The needle holds a little more, depending on the needle you fit.