In detail
Apple Music streams in AAC at 256 kbps by default, which uses about 115 MB per hour. Our calculator uses 0.15 GB per hour for music — a typical high-quality stream — so it reflects standard Apple Music listening well.
Lossless audio changes the picture. Apple's ALAC Lossless at CD quality (16-bit/44.1 kHz) uses roughly 0.6 GB per hour, and Hi-Res Lossless at up to 24-bit/192 kHz can use well over 3 GB per hour — as much as an HD video stream. Spatial audio with Dolby Atmos sits in between at roughly 0.3–0.4 GB per hour.
You can set streaming quality separately for Wi-Fi and cellular in Settings → Music → Audio Quality. Many listeners keep Lossless for home and choose 'High Efficiency' or standard quality on mobile, where the difference is hard to hear through Bluetooth headphones anyway.
Downloading albums and playlists over Wi-Fi is the most effective way to save mobile data. Note that lossless downloads also take far more storage — a single album in Hi-Res Lossless can exceed 1 GB.
Use the calculator above to combine Apple Music with the video services in your home. Even heavy music listening is usually a small share of a household's data — unless you stream Hi-Res Lossless on mobile.