Internet Speed
Mbps vs MBps: the unit confusion that costs people money
Two letters cause more buyer's remorse than any other detail in broadband marketing. Confusing megabits with megabytes leads people to pay for tiers they don't need and to misdiagnose perfectly healthy connections as 'slow'.
The 8x difference, explained
Networks measure bandwidth in bits. Computers measure files in bytes. One byte equals eight bits, so any time you convert between an ISP's advertised speed and a file-download progress bar, you divide or multiply by 8.
- 100 Mbps = 12.5 MB/s
- 500 Mbps = 62.5 MB/s
- 1 Gbps (1,000 Mbps) = 125 MB/s
How to read the units at a glance
The case of the 'b' is doing all the work:
- Lowercase 'b' — bits. Used by ISPs, speed tests, network gear (Mbps, Gbps).
- Uppercase 'B' — bytes. Used by file managers, browser downloads, cloud storage (MB/s, GB).
Real-world overhead
Even after the bit/byte conversion, sustained download throughput is usually 5–10% lower than the math predicts. TCP/IP packet headers, retransmissions, and protocol overhead all consume some capacity. A "100 Mbps" plan delivering ~11.5 MB/s sustained is healthy. Anything under ~10 MB/s sustained on that plan is worth investigating.
What this means for buying broadband
Before upgrading, do the math against your actual usage:
- 4K streaming peaks around 25 Mbps per stream — well under 100 Mbps even with three concurrent streams.
- Online gaming uses well under 1 Mbps — bandwidth is almost never the gaming bottleneck.
- Large game downloads benefit from gigabit, but only saturate it for minutes at a time.
Most households are oversold on bandwidth and undersold on Wi-Fi quality. See choosing an internet plan for a sizing framework.