Data Rate Converter
Convert internet speeds between Mbps, MB/s and other units, and work out how long a download takes.
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Internet providers sell speed in megabits per second (Mbps), while browsers, game launchers and file managers show progress in megabytes per second (MB/s). The two differ by a factor of eight, because a byte is eight bits, and that single letter b versus B is behind most "my 100 Mbps line only downloads at 12 MB/s" complaints. This converter puts every common unit side by side: bit/s, kbps, Mbps, Gbps and Tbps for network links, B/s, KB/s, MB/s, GB/s and TB/s for decimal byte rates, and KiB/s, MiB/s, GiB/s and TiB/s for the binary units many operating systems actually use when they say KB or MB.
Examples
100 Mbps
12.5 MB/s
Divide by 8 to go from bits to bytes.
4 GB at 100 Mbps
5 min 20 s
Best case with no overhead; about 6 minutes with 10% overhead.
20 Mbps for 1 hour
9 GB
A typical 4K stream for one hour.
Frequently asked questions
What is the difference between Mbps and MB/s?
Why is my download slower than the speed I pay for?
Are 1 Mbps 1,000,000 or 1,048,576 bits per second?
How long does it take to download 1 GB at 100 Mbps?
What is the difference between bandwidth and throughput?
How much data does a 4K video stream use per hour?
Is baud the same as bits per second?
Is anything sent to a server?
About Data Rate Converter
Type a value in any field and all the others update at once. Presets cover typical home connections and interfaces such as USB 2.0 (480 Mbps) and USB 3.0 (5 Gbps), so you can see at a glance that a 1 Gbps fibre line tops out at 125 MB/s before any overhead, or that a 300 Mbps plan gives about 37.5 MB/s on a perfect day.
The download time calculator answers the practical question: how long will a 4 GB game patch, a 50 GB backup or a 2 TB disk image take at a given speed? Enter the file size in decimal or binary units, the link speed in any rate unit, and an optional overhead percentage. Real transfers never reach the line rate: TCP/IP and Ethernet headers take roughly 3 to 5%, Wi-Fi loses much more to contention and signal quality, and a busy server or VPN may be the real bottleneck. Setting 10 to 20% gives a realistic estimate rather than the best case.
The third panel works the other way round and tells you how much data a sustained rate moves in a given period, which is handy for monthly data caps, backup windows, CCTV uploads or estimating how much a server can serve in a day. Everything is calculated locally in your browser; no speed test is run and nothing is sent anywhere.
Who named the bit, and why your ISP counts in it
The word bit, short for binary digit, first appeared in print in Claude Shannon's 1948 paper "A Mathematical Theory of Communication", where Shannon credited the statistician John Tukey with coining it. The byte came later, at IBM in the 1950s, and only settled on eight bits with the success of the System/360 in the 1960s.
Telecommunications kept counting in bits because serial links send one bit after another, and because the physical layer does not care about byte boundaries. Line coding also complicates things: classic Gigabit Ethernet over fibre (1000BASE-X) uses 8b/10b encoding, so the wire actually runs at 1.25 gigabaud to deliver 1 Gbps of data, and older USB and SATA links lost 20% the same way.
The older unit, the baud, honours Émile Baudot, whose 1870s telegraph code used five equal-length signals per character and became the basis of the teleprinter. Today baud and bit rate diverge almost everywhere, since Wi-Fi, cable and DSL modulations carry many bits per symbol.