Bandwidth Converter

Your ISP advertises 500 Mbps and your download client shows 60 MB/s and you're trying to figure out if you're actually getting what you pay for. The factor of 8 between bits and bytes trips up almost everyone the first time, and it's the single most common reason customers think their connection is slow when it isn't.

The converter handles bits per second, bytes per second, and the metric prefixes from kilo to tera so you can sanity-check a router spec, a Speedtest result, or a cloud egress charge in the same breath. The output uses decimal SI units (1000-based), which is what networking equipment uses — storage capacities use the binary 1024-based prefixes and that's a different conversation.

The core conversion is the bit-byte ratio: 1 byte = 8 bits, always. From there it's just metric-prefix arithmetic: 1 kbps = 1,000 bps, 1 Mbps = 1,000,000 bps, 1 Gbps = 1,000,000,000 bps. Networking standardized on decimal prefixes from the start because line rates were specified in clean decimal multiples (the original Ethernet at exactly 10,000,000 bps, T1 lines at 1,544,000 bps). Storage went binary because memory addressing is binary, and the powers of two (1024, 1,048,576) became convenient round-ish numbers that got mislabeled with the metric kilo and mega prefixes for decades. The IEC formalized binary prefixes (kibi, mebi, gibi) in 1998 to clean up the mess; networking ignored them, storage adopted them slowly.

A worked example: your ISP says "up to 1 Gbps." That's 1,000,000,000 bits per second. Divide by 8 to get bytes: 125,000,000 bytes per second. Divide by 1,000,000 to express in megabytes: 125 MB/s. So a perfect gigabit line tops out at 125 MB/s on a download. Real-world overhead from TCP/IP headers, retransmissions, and far-end server limits eats some of that — expect 100-115 MB/s on a clean gigabit line, which is exactly what every speed test will show you when conditions are good.

Where this gets confusing in practice: you'll see units mixed up casually in product copy. A USB 3.0 port advertises "5 Gbps" but the actual usable throughput after 8b/10b encoding overhead is closer to 4 Gbps, and the OS shows transfer speeds in MB/s. A Wi-Fi 6 router claims "9.6 Gbps" but that's the aggregate across multiple streams and the single-client number is much lower. Always check what the unit refers to — line rate, sustained throughput, peak burst, or aggregate — before comparing two specs.