One of the most common questions we get about planner discs is simple: "will these actually work with my planner?" Disc sizing isn't perfectly standardized across brands, so it's worth understanding how compatibility actually works before you order. Here's what you need to know.
Why disc compatibility varies by brand
Unlike ring binders, which are governed by a handful of universal ring sizes, disc-bound systems were popularized by a few different brands independently, each with slightly different disc diameters and punch patterns. That means a disc from one brand isn't always a perfect match for pages punched for another. The good news is that most disc-bound systems on the market today cluster around a small number of common sizes.
Happy Planner
Happy Planner uses a proprietary disc size that's become one of the most widely recognized in the disc-bound space. Pages and accessories punched for Happy Planner are generally compatible with discs sized to match, so if you're switching from an official Happy Planner disc to one of ours, check that you're ordering the matching diameter for your page punch.
TUL and Levenger
TUL (sold through Office Depot) and Levenger's Circa system each use their own slightly different disc sizing as well. Pages punched specifically for TUL or Circa systems are sized for those systems' discs, so compatibility comes down to matching diameters rather than brand names. Our 32mm discs and 28mm discs cover the two most common sizes used across these systems.
Silver Star 32mm Discs
Silver 28mm Discs
How to check compatibility before you buy
The most reliable way to confirm compatibility is to measure the diameter of the disc you're currently using (or the punched holes on your pages) and compare it against the size listed for the discs you're considering. Don't rely on brand name alone, since two brands can use the same size disc, or the same brand can offer multiple sizes across different product lines.
What if I'm not converting an existing planner?
If you're starting fresh rather than converting existing pages, compatibility is simpler: pick a disc size first, then buy or punch pages specifically for that size going forward. Our Black Crescent Moon discs and Red Butterfly discs are both great starting points if you're building a new setup from scratch rather than migrating one.
Black Crescent Moon Discs
Red Butterfly Discs
A quick note on brand names
Brand names like Happy Planner, TUL, and Levenger are used here only to describe general compatibility categories that shoppers commonly search for. Our discs aren't affiliated with, licensed by, or endorsed by those brands. When in doubt about a specific product's fit, comparing exact measurements is always more reliable than matching by brand name alone.
Still not sure which size you need?
Browse our full Planner Discs collection to compare all our available sizes and styles side by side, and reach out if you need help matching a specific existing setup.