Bandwidth & Throughput Converter (Mbps ↔ MB/s)
Plug in any network speed (1 Gbps fiber, 500 Mbps Wi-Fi, an LTE link) and instantly convert across every common unit: bit/s (the ISP / Ethernet label), decimal Byte/s (storage spec sheets) and binary Byte/s (what your OS and browser actually show). Enter a file size and it estimates the real transfer time in days/hours/minutes/seconds — avoiding the classic "100 Mbps ≠ 100 MB/s" mix-up (off by a factor of 8).
Please enter a valid number.
Estimated transfer time
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bit ↔ Byte conversion
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8 bit = 1 Byte. So "100 Mbps" ≠ "100 MB/s" — divide by 8 to get the MB/s figure your browser shows.
bit/s (bandwidth)
Used by Ethernet, Wi-Fi, ISP labels.
Byte/s (decimal)
1 KB/s = 1000 B/s. Used on SSD / storage spec sheets.
Byte/s (binary, IEC)
1 KiB/s = 1024 B/s. Used by OSes and app progress bars.
Formula
rate_bps = value × factor[unit] MB/s = bps ÷ 8 ÷ 1 000 000 (decimal, manufacturer label) MiB/s = bps ÷ 8 ÷ 1 048 576 (IEC binary, what the OS shows) transfer_seconds = file_bytes × 8 ÷ bps
- · 8 bit = 1 Byte: divide the ISP's Mbps (megabits) by 8 to get the MB/s (megabytes) your browser shows.
- · Decimal units (kbps, Mbps, Gbps, KB/s, MB/s, GB/s) are 1000-based — SI prefixes per NIST SP 811 and IEC 80000.
- · Binary units (KiB/s, MiB/s, GiB/s) are 1024-based — IEC 80000-13:2008 binary prefixes, used by most OSes and app progress dialogs.
- · Example: a 1 Gbps fiber link = 1000 Mbps = 125 MB/s (decimal) ≈ 119.21 MiB/s (binary).
- · Real-world throughput is usually below the line rate — TCP overhead, half-duplex Wi-Fi, server-side rate limiting and HTTP/TLS headers all take a cut; budget 10–20 % headroom.
- · Major HK ISPs (HKBN, Netvigator, Hong Kong Broadband, CSL, 3) all advertise speeds in bit/s (Mbps / Gbps).
Frequently asked
Why does my 1 Gbps fiber max out at around 110 MB/s instead of 125?
Two reasons. First, units: 1 Gbps (gigabit) = 125 MB/s (decimal megabyte). Tools like Windows Task Manager and macOS Activity Monitor often label MB/s but actually mean mebibytes (MiB/s), and 1 Gbps ≈ 119.2 MiB/s — already a smaller number. Second, protocol overhead: Ethernet framing, IP/TCP/TLS headers eat 5–8 % of line rate; Wi-Fi adds half-duplex / retransmissions; many servers throttle individual connections. Real application throughput is typically 85–95 % of the line rate. A wired speedtest hitting 940 Mbps is perfectly normal — that's ~117 MB/s decimal or 112 MiB/s binary.
What's the difference between KB / MB and KiB / MiB? Which should I use?
KB / MB / GB / TB are decimal (SI): 1 KB = 1000 B, 1 MB = 1 000 000 B. Storage manufacturers (HDD, SSD, USB) and all network specs advertise in decimal — bigger marketing numbers. KiB / MiB / GiB / TiB are binary (IEC 80000-13:2008): 1 KiB = 1024 B, 1 MiB = 1 048 576 B. Windows, Linux, parts of macOS, and RAM specs use binary because CPU/OS addressing is in powers of two. That's why a "1 TB" drive shows up as ~931 GiB in Windows ("missing" space): 1 × 10^12 B ÷ 2^40 B/TiB. Rule of thumb: use KB/MB when reading network or storage spec sheets; use KiB/MiB when interpreting what the OS shows.
5G ads claim "20 Gbps" — what does that mean for my actual phone download speed?
20 Gbps is the theoretical 5G NR peak — assuming mmWave bands, full carrier aggregation, a single device hogging the cell, and no obstacles. In practice: (1) HK mmWave (24/26/28 GHz) deployment is limited; most 5G runs in Sub-6 GHz (n78 3.5 GHz, n28 700 MHz). (2) One cell's bandwidth is shared across all users. (3) Indoor penetration losses hurt. Real-world numbers from OpenSignal / Speedtest HK 2024–2025: average 5G phone download 200–400 Mbps; peaks of 1–2 Gbps (≈ 125–250 MB/s). That's already 10× faster than typical 4G LTE (30–80 Mbps), but still 50–100× below the advertised 20 Gbps headline.
Why does my "5 Gbps" USB 3.0 drive copy at only 50 MB/s?
5 Gbps is USB 3.0 / SuperSpeed raw signaling rate. 8b/10b line coding strips it to ~4 Gbps (500 MB/s); USB protocol framing and SCSI/UASP overhead leave about 400 MB/s of theoretical application throughput. But the real bottleneck is usually the NAND flash itself — cheap USB sticks use QLC/TLC NAND with tiny DRAM caches and sustain only 30–80 MB/s for large writes (and drop further once the SLC cache is exhausted). To approach 500 MB/s sustained you need an NVMe-based external SSD over USB 3.2 Gen 2x2 (20 Gbps) or Thunderbolt — not a generic USB 3.0 flash drive.
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