Two hundred seventy yards of fabric and 10,000 Swarovski crystals made up Cinderella's ball gown, created by costume designer Sandy Powell.
"There are miles and miles and miles of frills. Some incredible thing like 80 miles of stitching," the three-time Oscar winner told ET.
Lily James, 25, plays Cinderella in this retelling of the classic story about a servant step-daughter who wins the heart of a prince. You'll be happy to learn that the glass slippers were relatively comfortable, as they required some movie magic.
"I wore silver with green spot slippers so they CGI slipped it onto my foot," Lily told ET.
The film also stars Helena Bonham Carter as the Fairy Godmother, while Cate Blanchett plays the wicked step-mother Lady Tremaine. It's Cate's character who puts on the real fashion in the movie, out today, with killer hats and dramatic '40s-inspired silhouettes.
Watch the video for a sneak at the ballroom dancing scene, which used no CGI.