The Ultimate Pen Refill Guide

Are you confused about which refills will fit your pen?

Pen refills are available in many different shapes and sizes. Some refills are a standard size complying with ISO Standard 1257 and can be swapped between pens made by different manufacturers.

Whereas others are known as a propriety size pen refills, they are a specific size and shape and will only fit pens made by that particular manufacturer.

In this guide, we clearly explain the different types of pen refills and which pens they fit.

1. A2 Pen Refills

A2 Pen Refill

The A2 pen refill is known as a standard-size ballpoint refill it measures 3.2mm in diameter and 106.8mm in length.

It is a metal refill with a narrow tip and, for many years, was used in retractable pens. The A2 refill has primarily been superseded due to modern manufacturing techniques and the arrival of plastic and propriety refills.

There are still some manufacturers that still make the A2 refill. These are Schneider with their Schneider 75 Express and Silver refills.

The German specialist refill manufacturer Schmidt also makes an A2 refill which is the Schmidt refill 700 M.

2. B3 Pen Refills

B3 Pen Refill

The B3 pen refill was used in stick pens. Its length and diameter can vary, but according to the Iso standard 1257, it should measure either 132mm in length x 103mm in diameter or 63mm in length x 43mm in diameter.

The B3 pen refill is usually made from plastic and has the large shouldered tip housing that holds the refill in place in the pen’s barrel.

This type of refill is not as popular as it once was, but Bic uses the B3 size refill extensively in its Crystal range of ballpoint pens.

3. C1 Cross Style Pen Refills

C1 Pen Refill

The C1 refill is referred to by ISO 1257 as a ballpoint international refill; however, this size refill is what Cross uses in their ballpoint pens, so everyone calls it a C1 Cross style refill.

As for the refill itself, it measures 117.4mm in length and 3.05 mm in diameter. It is usually made from metal and has a plastic threaded collar to secure the refill.

C1 Cross-style refills are typically used in twist-action ballpoint pens where the pen barrel is rotated to extend and retract its tip.

One of the advantages of twist-action ballpoint pens is that they do not require a spring; push-button ballpoint pens need to extend and retract the tip.

4. D1 Pen Refills

D1 Pen Refill

D1 pen refills are one of the most popular standardized refill sizes, measuring 67mm in length and 2.3mm in diameter.

They usually have a metal barrel and are used by manufacturers in mini ballpoint pens and multi-function pens.

There are over twenty-five D1 refills made by major pen manufacturers, including ballpoint, highlighter, gel, and pressurized refills.

Check out our Ultimate Guide to D1 Refills for more information.

5. Euro Format Rollerball Pen Refills

Schmidt 5888 Euro Refill

According to ISO 1257, the RB standard rollerball refill measures 110mm in length and 6.3mm in diameter.

Refills that comply with the RB standard are referred to as Euro Format refills. In theory, these refills should be interchangeable with others that comply with the ISO RB standard.

However, this is not the case as the pen manufacturers did not strictly adhere to the standard.

We have covered Euro Format refill compatibility in-depth in our Ultimate Guide to Euro Format Pen Refills. Check out the different Euro Format refills available and how to tell if it will fit your rollerball pen.

6. G1 Pen Refills

G1 Pen Refill

The G1 ballpoint pen refill measure 106.8mm in length and 4.9mm in diameter. It is not a typical size used in modern pens.

It has a metal barrel and was the standard ballpoint pen refill in ISO 12757-1.

Older PaperMate pens had Lubriglide refills that were a G1 refill, and Aurora still makes them for some of their ballpoint pens, and the Schneider Schneider Express 225 is also a G1 format refill.

7. G2 Parker Style Pen Refills

G2 Pen Refill Parker Style

The G2 refill measures 98.1mm in length and 6.3mm in diameter it is one of the most popular refill sizes available and is known as a Parker Style G2 Refill.

Parker Pens originally used its shape and dimensions and were initially copyrighted to prevent other pen manufacturers from making refills that would fit their pens.

At some point, Parker relinquished the copyright of their G2 refill, and its dimensions were standardized in ISO 1257.

Over 50 different Parker Style G2 refills are available from the major pen manufacturers. with either metal or plastic barrels in a range of tip sizes with ballpoint, gel, or hybrid ink.

There are even printed 3d adapters that allow you to use a D1 refill in pens designed to take G2 refills giving you even more options to refill your pens with.

For more information, check out our Ultimate Guide to Parker Style G2 Refills, where we give details of all the G2 refills made by the different pen brands.

Note the Pilot G2 refill is not a Parker-style refill and does not fit pens that take a Parker-style G2 refill.

8. Japan Type Refills

Japan Type Pen Refill

The Japan-type refill is a ballpoint pen refill that measures 3.0mm in diameter; the refill length can vary.

They have a crimped area way up the barrel designed to stop the spring from sliding up the refill when the push button is pressed.

Because the position of the crimped area and the refill length varies, Japan-type refills are not as interchangeable as the refill types.

Most of the main Japanese pen manufacturers use this type of refill, including:

  • Ohto
  • Pentel
  • Pilot
  • Uni-Ball
  • Zebra

9. X10 Pen Refills

X10 Pen Refill

The X10 pen refill measures 106.8mm in length and 3.05mm in diameter it is known as the standard ballpoint pen refill. it has a metal barrel and a crimped area to retain the pen’s spring.

Unlike modern-day ballpoint pens, it has a narrower tip, approximately 1.6mm, compared to 2.0mm.

The X10 pen refill was widely used by pen manufacturers such as Paper Mate between the 1940s and the 1980s.

Today there are only a few X10 refills available:

  • Aurora Thesis Ballpoint Pen Refill
  • Fisher PS1F Refill for 1950s Paper Mate Pens
  • Schmidt Refill 700M

Although the Aurora Thesis refill is in all likelihood, the Schmidt Refill 700 branded Aurora by Schmidt for them.

10. X20 Pen Refills

X20 Pen Refills

The X20 pen refill measures 106.8mm long and 3.05mm in diameter. Although it looks very similar to the X10 & its length and diameter are the same, and the tip size is the biggest difference between the two pen refills.

The X20 has a lot bigger tip, around 2.2mm, compared to the narrow 1.6mm X10. This means that the X20 and X10 refills are not interchangeable.

The X20 refill usually has a plastic body; refills of this type are common in many cheaper unbranded pens.

Bic also uses them in pens such as the Bic Click, Ecolutions & Velocity ballpoint pens. However, they can have a metal body, and the Schneider Office 765 is a refill of this type.

11. Pressurized Pen Refills

Fisher PR Refill 9 Ink Colors

Paul Fisher invented the first pressurized pen refill in the 1960s and launched the Fisher Space Pen, which is by far the most popular and well-known of all the pens fitted with a pressurized refill.

The benefit of a pressurized refill is that the ink is constantly at the tip of the ball, allowing them to do things other ballpoint pens can, such as write on greasy surfaces, wet paper, or even underwater if you ever feel the need.

Because the ink is always at the tip, pressurized pens can also write upside down or in zero gravity, which is why both Nasa and the Russian Space Agency use them.

The ink is in a sealed chamber with a pressurized refill and will last longer than a standard ballpoint pen refill. In fact, Fisher claims that the ink in their refills will still be good and can be used up to 100 years from when they were made.

The other benefit is that pressurized refills can be used in extreme temperatures from minus 35 to 121 degrees Celsius.

It is unlikely that most people will test them out in such extreme temperatures, but it gets the point across that they can work anywhere in the world.

Fisher Space pens are not the only pens that use pressurized refills. There are a few others that are generally a lot cheaper to buy than the Space Pens.

Fisher Space Pen Alternatives

  • Diplomat Spacetec Ballpoint Pens – Use Schmidt refills
  • Pilot Down Force Ballpoint Pens – Heavy-duty plastic barrel pens for outdoor use.
  • Tombow Airpress Ballpoint Pens – Wide barrel & rubberized grip
  • Uni Power Tank Ballpoint Pen – Cheapest pressurized pen to buy. Check out our review.
  • Schmidt Pressurized Refills – Schmidt 950M Megaline (Parker Style) & Schmidt 620M (D1 size)

12. Propriety Pen Refills

A propriety refill is made by a pen manufacturer to a specific size and shape that is unique to them.

The main reason the pen manufacturers do this is to ensure that you have to buy the refills for their pens and cannot use cheaper alternative refills from other manufacturers.

13. Alternative Refill Manufacturers

There are many Chinese-made alternative refills for sale on both eBay and Amazon. The quality and compatibility of these are not guaranteed, but if they are all you can find, they are better than having a pen that cannot be used.

However, two specialist refill manufacturers make a range of high-quality refills for many major pen brands.

These are Monteverde and Schmidt.

13.1. Monteverde

Established in 199, Monteverde is a U.S.-based pen manufacturer renowned for its innovative designs and being at the forefront of technological advances.

Their refills use what they describe as Soft-Roll™ ink technology; basically, it is a specially developed low viscosity ink that is smooth writing. Low Viscosity ink is often referred to as hybrid ink; check out our guide Ballpoint Rollerball or Gel Pen? for more information.

Monteverde also manufactures a range of alternative refills that have the same ink and are compatible with pens made by other brands.

Monteverde alternative refills are available for the following pen brands:

  • Cross – Ballpoint & Rollerball Pen Refills
  • Lamy – Ballpoint Pen Refills
  • Montblanc – Rollerball Refills
  • Parker – Ballpoint & Rollerball Pen Refills
  • Pelikan – Rollerball Refills
  • T. Dupont – Ballpoint Pen Refills
  • Sheaffer – Ballpoint & Rollerball Pen Refills
  • Waterman – Ballpoint Pen Refills

13.2. Schmidt

You may not be aware of the name Schmidt, but the chances are if using a high-quality pen from a designer label, it is fitted with a refill made by Schmidt.

Schmidt Technology is a specialist German pen manufacturer making refills since the 1950s. They are renowned for their research and development department, which results in them producing high-quality refills that are used by pen manufacturers worldwide.

If you see an alternative refill for your pen-branded Schmidt, then you know that it will be a high-quality, smooth writing, reliable refill.

Check out our Ultimate Guide to Schmidt Pen Refills for more information

14. Pen Brand Refills Complete Guides

We have written a series of complete refill guides for some of the major pen brands. The guides include every refill for that manufacturer, including ink colors and tip sizes, which pens they fit, and alternative refills if available.

If you have a pen and are unsure what refill it takes or wants to know if there is a cheaper alternative, then the guides are well worth looking at.

Check out Pen Brands Refills for the complete list of pen refill guides. You may also be interested in our in-depth guide to Uncovering Your Ideal Pen Refill.

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Peter Warrior: Pen & Pencil Expert

With nearly a decade of experience in the pen industry, I successfully ran an online pen business for 9 years. My deep-rooted passion for pens and pencils led me to become a part-time blogger, where I've dedicated myself to sharing the wealth of knowledge I've amassed over the years. I'm a firm believer in the power of the written word, as echoed by Malcolm Forbes: "Putting pen to paper lights more fire than matches ever will." My expertise is not just rooted in business, but in the genuine appreciation and understanding of the art of writing instruments.

2 thoughts on “The Ultimate Pen Refill Guide”

  1. I have a custom mini pen and trying to find a way to refill or replace. I need to send a photo so you can see. The tip of the pen unscrews and it seems like the refill can some how disconnect from that, but I’m not able to unscrew or pull it out. I thought someone here might know.

  2. Excellent article on pen refills. Do you know where I can find a KeySmart Nano Pen refill? It’s 63mm long and about 2mm in diameter.
    Thank you,


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