Mbps vs MB/s: the divide-by-8 rule

4 min read · Updated July 12, 2026

Your plan says 500, your download meter says 60. Nobody is cheating you — two industries simply measure with different units.

Bits for lines, bytes for files

Networks are sold in megabits per second (Mbps, small b). Files and download meters use megabytes (MB, big B). One byte is eight bits — so divide your plan by 8 to predict file speeds.

A 100 Mbps line moves at most 12.5 MB/s; 500 Mbps ≈ 62.5 MB/s; a gigabit ≈ 125 MB/s. Your 60 MB/s on a 500 Mbps plan is exactly right.

Where the last few percent go

Real transfers carry addressing and reliability overhead (TCP/IP headers, acknowledgements, encryption framing), which typically consumes 5–10% of the raw line rate. A healthy 500 Mbps connection delivering ~56–59 MB/s on a single well-served download is behaving normally.

Slower-than-that usually is not the line at all: the server you download from, a Wi-Fi hop, a VPN, or your disk can each be the real ceiling.

Quick reference

At 25 Mbps: a 4 GB movie in ~21 min, a 50 GB game in ~4.5 h. At 100 Mbps: ~5.3 min and ~68 min. At 500 Mbps: ~64 s and ~14 min. At 1 Gbps: ~32 s and ~7 min.

Notice the pattern: big plans mostly buy shorter waits on big files. If your everyday pain is laggy calls or games, the guide on latency will help more than a bigger number.

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