Bits, bytes and prefixes
Network speed is often measured in bits per second, while file size is often measured in bytes. Decimal prefixes use powers of 1000; binary prefixes use powers of 1024. The calculator needs to state which convention it uses.
Download time
Download time is file size divided by transfer speed after converting units. Real downloads can be slower because of overhead, congestion, server limits, Wi-Fi conditions and throttling.
Technology costs
Cloud, API and storage estimates are clearer when they separate quantity, unit price, billing period and free tiers. They also need to state that provider pricing changes and must be checked at the source.
Common mistakes
- Using Mbps as if it were MB/s.
- Comparing GB and GiB without conversion.
- Ignoring upload speed for backups and video calls.
- Using outdated vendor prices as if they were live data.
Data rate and storage examples
Bits and bytes are a common source of errors. A 100 Mbps connection transfers at a theoretical 12.5 MB/s because 8 bits = 1 byte. A 1 GB file is about 8 gigabits in decimal units, so the theoretical transfer time at 100 Mbps is about 80 seconds before overhead, congestion or server limits.
Storage also has decimal and binary conventions. 1 GB is 1,000,000,000 bytes, while 1 GiB is 1,073,741,824 bytes. A useful result shows the convention it uses, especially for disk capacity, memory, cloud storage and bandwidth planning.
Useful calculators
FAQ
Why is Mbps not the same as MB/s?
Mbps means megabits per second; MB/s means megabytes per second. One byte is eight bits.
Why does real download time differ?
Network overhead, congestion, server limits and device conditions can reduce effective speed.
Can technology cost calculators show live prices?
Only when connected to a maintained provider data source. Otherwise, user-entered or documented sample prices must be labelled clearly.
Last reviewed: 2026-05-16.