Best Fountain Pen Converters and Filling Systems
A converter unlocks the full ink market for cartridge pens and is often the second purchase after a first fountain pen. Beyond standard piston converters, we cover squeeze converters, high-capacity options, eyedropper conversion kits, and filling systems for pens with proprietary mechanisms. Fit matters most: a wrong-size converter seals poorly and drips.
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The short answer
The Pilot CON-70+ is the best fountain pen converter for most writers, holding more ink than any other standard converter at approximately 1.1ml and fitting the full range of Pilot cartridge-compatible pens. Writers with Lamy pens need the brand-specific Lamy Z28 converter, which fits no other brand but seats perfectly and is widely available.
Top Pick
Pilot CON-70+ Ink Converter
The highest-capacity standard converter from Pilot, holding approximately 1.1ml of ink. Fits all Pilot cartridge-compatible pens including the Metropolitan, Kakuno, Prera, Custom 74, and Explorer. The plus version uses a push-knob fill mechanism.
Best for Pilot pen owners who want the most ink capacity in a standard converter
2 TWSBI ECO Demonstrator Piston Filler
Not a converter but a complete piston-filling pen with a visible ink reservoir of approximately 1.9ml. Listed here because writers often move to a piston pen to eliminate converter limitations. The ECO is the most recommended entry-level piston filler.
Best for Writers ready to step up from converter pens to a dedicated piston filler
3 Lamy Z28 Ink Converter
The standard piston converter for Lamy pens with the Lamy cartridge-converter fill section, including the Safari, Al-Star, Studio, and Joy. Holds approximately 0.8ml, transparent, and widely available from any Lamy retailer.
Best for Lamy Safari, Al-Star, Studio, or Joy owners
4 Platinum Converter 700S
A piston converter for Platinum fountain pens including the Preppy, Plaisir, Cool, Century, and Izumo. The Platinum proprietary converter section fits no other brand but holds approximately 0.8ml and seals reliably.
Best for Platinum pen owners including Preppy, Plaisir, and Century users
5 Kaweco Sport Eyedropper Conversion Kit
A silicone grease and O-ring kit specifically sized for the Kaweco Sport's grip-barrel thread. Converts the plastic Sport to an eyedropper pen holding approximately 1.4ml of ink. Straightforward to apply and reverse.
Best for Kaweco Sport owners who want maximum ink capacity without upgrading the pen
The method
How we chose
We evaluated each option on fit, build quality, daily usability, and value. Our top pick, Pilot CON-70+ Ink Converter, earned the spot because the best pilot converter available and an immediate upgrade over the con-40 on capacity alone. The comparison above highlights exactly who each pick is best for.
Related guides
FAQ
Best Fountain Pen Converters and Filling Systems: FAQ
Are fountain pen converters universal?+
No. Converters come in brand-specific fits. The most common sizes are European standard (used by TWSBI, Kaweco, Platinum, and many others) and proprietary fits used by Pilot, Lamy, Sailor, and Pelikan. A Pilot converter will not seat in a Lamy pen, and vice versa. Always confirm converter compatibility with your specific pen model before buying.
How do I fill a converter properly?+
Submerge the nib fully in the ink, not just the tip, so the feed channel primes properly. For a piston converter, twist the knob back fully before submerging, then twist forward to draw ink. For a squeeze converter, depress fully, submerge, then release. Wipe the nib before capping and expect the first fill to be lighter as air purges from the feed.
What is an eyedropper conversion and is it safe?+
Eyedropper conversion turns the barrel itself into the ink reservoir by sealing the grip-barrel junction with silicone grease. Most pens with an all-plastic body and a standard cartridge-converter section can be converted. The risk is leakage if the seal is not solid. Silicone grease applied to the threads is the standard fix, and the pen should be tested over a paper towel before capping and pocketing.
How much more ink does a converter hold versus a cartridge?+
A standard international cartridge holds about 0.7ml to 0.9ml of ink. The Pilot CON-70+ converter holds approximately 1.1ml. A full eyedropper-converted Kaweco Sport holds around 1.4ml. The capacity difference matters most for daily journal writers who refill frequently; casual writers may not notice the difference between a converter and a cartridge.