Pens and Pencils | Reviews and Data

Fountain Pen Cartridge Guide

Unsharpen may earn a commission when you buy through links on our site.

In theory, using a fountain pen cartridges should be easy — you insert one into your pen and you start writing. In practice, they are rather confusing. Some cartridges only work on one brand of pen, some work on lots of pens… and they all look alike! Cartridges are rarely labeled well and the downside of messing up a cartridge installation can be a broken pen (bad) or a leaky cartridge (often worse).

This guide will answer most common fountain pen cartridge questions as well help you visually identify which cartridge is which.

Popular Pen Cartridges Compared

Here is a guide comparing different popular fountain pen cartridges side-by-side.

In the image you can see cartridges ranging from the longest to the shortest: Parker Quink, Lamy T10, Pilot, Platinum, Sailor, Olika (also Hero), and then finally standard international short. This isn’t an exhaustive list, but it should give you some idea of how the cartridges compare.

And here is a side shot of each of the cartridges so you can visually identify them by the opening by which ink flows through once they are punctured.

Visual Guide To Fountain Pen Cartridges

Have a drawer full of fountain pen cartridges but can’t figure out which is which? Check out the image below to tell one cartridge from another.

Standard International Short Cartridge

The most common and most affordable fountain pen cartridge, the standard international short will fit most fountain pens. If you are in question what cartridge a pen takes, it’s normally this. This is a very small cartridge with a capacity of about 0.8 ml.

This cartridge has a hard step at the front and a small plastic ball inside once it is opened. It has a slight taper to its design and always has maximum width of 7.0 mm with an inner diameter of about 4.0 mm (some makers undersize this slightly).

Many, many companies makes these cartridges from no-name ink brands to office-focused brands like Schneider, to high-end heritage ones, like Pelikan.

Pilot Cartridge

Pilot’s cartridge is known for its large collar at the open end, making it relatively different from the rest of the cartridges. The  plastic is relatively soft at the bottom so it can be squeezed.

These cartridges have a very large inner diameter, about 6.0 mm so they are interchangeable with almost no other pen brands.

Platinum Cartridge

Platinum cartridges are most easily identified by their tapered shape and metal ball at the insertion end. They are otherwise pretty standard, having a step-down at the front end, a 6 mm outer diameter, and a clear plastic body. Their plastic is on the hard side so it’s a bit difficult to squeeze them and to push some ink out.

The inner diameter of Platinum cartridges is about 4.1 mm, which is on the large side. This width plus the length of the cartridge explains why these will not work in place of an international short cartridge and these work with almost no pen brands aside from Platinum and Nakaya.

Lamy Cartridge

Lamy’s T10 Giant cartridge is one of the most distinctive of the shapes and the most easy to visually identify. It’s a long refill with a capacity that is higher than that of any Lamy converter.

These cartridges use a 3.3 mm inner diameter which makes them work on a number of “small bore” Chinese fountain pens as well as some Parker and Aurora pens.

Parker Cartridge

Parker has the longest of any common fountain pen cartridge, with a huge 1.4 ml capacity. That’s about twice the capacity of most fountain pen converters. The cartridge might look straight in pictures, but it has a long, gentle taper, gradually getting narrower towards the top. This allows it to fit into Parker’s older pens, which tend to be thinner and more taper than today’s pens.

These cartridges have an inner diameter of about 3.5 mm, which is why they are so close to Lamy cartridge and are sometime interchangeable with them.

Sailor Cartridge

Sailor’s cartridges are not tapered and are shorter then most of the major types. It’s one of the simplest designed but can be distinguished by the arrow pointing towards the end the ink flows from. This is necessitated by the lack of a taper.

Sailor uses a small cartridge with a wide, 5.0 mm inner diameter.

Which Cartridge Does Each Fountain Pen Company Use?

  • Acme – Standard International
  • Amazon Basics – Standard International
  • Ancora – Standard International
  • Aurora – Aurora, Parker, or Lamy
  • Bexley – Standard International
  • Caran d’Ache – Standard International
  • Cartier – Standard International
  • Conklin – Standard International
  • Conway Stewart – Standard International
  • Cross – Cross
  • Delta – Standard International
  • Diplomat – Standard International
  • Dunhill – Standard International
  • Eboya – Standard International
  • Faber Castell – Standard International
  • Itoya – Standard International
  • Jean Pierre Lepine – Standard International
  • Kaweco – Standard International
  • Krone – Standard International
  • Lamy – Lamy
  • Montblanc – Standard International
  • Montegrappa – Standard International
  • Monteverde – Standard International
  • Nakaya – Platinum
  • Namiki – Pilot
  • Omas – Standard International
  • Osmiroid – Standard International
  • Parker – Parker or Aurora
  • Pilot – Pilot
  • Pelikan – Standard International
  • Pentel – Standard International
  • Platinum – Platinum
  • Recife – Standard International
  • Retro 51 – Standard International
  • Rotring – Standard International
  • Sailor – Sailor
  • Schmidt – Standard International
  • Schneider – Standard International
  • Sensa – Standard International
  • Sheaffer – Standard International
  • S.T. Dupont – Standard International
  • Stipula – Standard International
  • Taccia – Standard International
  • Tombow – Standard International
  • Visconti – Standard International
  • Waterford – Standard International
  • Waterman – Standard International
  • Wing Sung – Parker, Aurora, 3.4 mm Chinese cartridges
  • Yard O Led – Standard International

Which Cartridges Work Across Companies?

These swaps won’t be recommended by the companies but they will work. They will save you money and are super useful in a pinch.

Aurora fountain pens will generally, but not always take Parker cartridges and/or Lamy cartridges thanks to them all having a thin profile and an opening with an inner diameter that is very close to one another.

Wing Sung, the popular Chinese fountain pen maker, doesn’t sell their own cartridges but Parker’s cartridges work quite nicely in these pens and are very easy to find.

(Please email your suggestions for this! We’ll add cartridge hacks as we find them.)