Last month, Apple released Safari 10 on OS X and iOS. Among other great new features, we were pleased to see that this new version of Safari supports the WOFF2 font format and the CSS font loading API.

WOFF2 is the next iteration of the popular WOFF format, which promises much better compression. With the Safari 10 release all major browsers now support WOFF2. In fact, in July 2016 WOFF2 overtook WOFF as the most served font format on Typekit.

Today we’re happy to announce two small changes we’ve made. As of this week, we serve WOFF2 to Safari 10 on OS X Sierra and iOS 10. You’ll receive this update automatically, so there is no need to republish your kits.

The kit size in WOFF (left) and WOFF2 (right).

We’ve also changed the way kit sizes are calculated in the kit editor. Previously, the kit size was calculated using the file size of WOFF files; we’ve changed this to WOFF2, as it’s the new dominant font format. The kits themselves aren’t changing at all — browsers will still automatically receive the most optimal format they support — but the kit editor will reflect the actual kit size that most of your visitors will receive.

As always, let us know if you have any questions about this change; you can comment here, send an email to support@typekit.com, or find us on Twitter.