Great Dane: crate, bed and harness size
AKC weight: 110-175 pounds (AKC Breed Weight Chart). The Great Dane is #22 in AKC's 2025 ranking (AKC).
Crate: Over 110 lb, beyond the MidWest iCrate chart (MidWest iCrate Dog Crate Size Guide (manufacturer PDF))
Bed: X-Large rectangle bed (53 x 35 in) (Orvis Dog Product Sizing Guide (Rectangle bed))
Harness: Measure your dog's chest girth, then check the Ruffwear girth chart. No breed standard lists girth.
Photo: Lilly M, CC BY-SA 2.5, via Wikimedia Commons (cropped).