The estimate
Mbps × hours × 0.45. Example inputs are estimates, not a measured Dream stream. Adaptive quality and transport overhead can change actual use.
Read the result correctly
One megabit per second for one hour is approximately 0.45 decimal gigabytes: 1,000,000 bits per second × 3,600 seconds ÷ 8 bits per byte ÷ 1,000,000,000 bytes per GB. Multiply by average bitrate and hours. This describes a constant average, not a measured Dream source.
Adaptive delivery, selected quality, transport overhead and background activity change actual consumption. Use your device or provider usage meter for billing decisions.