Bandwidth Calculator

Bandwidth vs throughput

These terms are often used interchangeably, but they mean different things. Bandwidth is the maximum theoretical capacity of a link: the widest pipe you could push data through. Throughput is the actual amount of data successfully transferred in a given time period.

Throughput is always lower than bandwidth due to protocol overhead, congestion, error correction, and other factors. A 100 Mbps Ethernet link will never deliver 100 Mbps of application data. The real-world throughput is typically 80–95% of the advertised bandwidth, depending on the protocol and conditions.

Decimal vs binary units

The networking and storage industries use two different conventions for unit prefixes, which causes endless confusion:

• Decimal (SI): 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes. Used by network equipment manufacturers, ISPs, and hard drive makers. This is why your "1 TB" hard drive shows as ~931 GB in your operating system.
• Binary (IEC): 1 KiB = 1,024 bytes, 1 MiB = 1,048,576 bytes. Used by operating systems and memory manufacturers. More accurate for computing since memory is addressed in powers of 2.

For bandwidth calculations, decimal units are standard. When your ISP says "100 Mbps", they mean 100,000,000 bits per second. Use the toggle above to switch between conventions if you need to work in binary units.

Real-world efficiency factors

The "80% efficiency" option in the transfer time calculator accounts for common overhead:

• TCP/IP headers: Each packet carries 20–60 bytes of TCP header and 20 bytes of IP header, reducing the payload ratio.
• Ethernet framing: Each frame adds 26 bytes of overhead (preamble, header, CRC, interframe gap).
• Protocol overhead: TCP acknowledgements, retransmissions, window sizing, and congestion control all reduce effective throughput.
• Shared medium: On wireless networks or shared links, contention and collision avoidance further reduce available bandwidth.

80% is a reasonable estimate for wired Ethernet. For Wi-Fi, 50–70% is more realistic. For VPN connections, subtract another 5–15% depending on the encryption overhead.

Planning office bandwidth requirements

A common rule of thumb is 2–5 Mbps per user for general office work (email, web browsing, cloud apps). Adjust upward for:

• Video conferencing: 3–8 Mbps per simultaneous call (HD video).
• Cloud-heavy workflows: 5–10 Mbps per user for teams working primarily in cloud applications like Google Workspace or Microsoft 365.
• Development teams: 10–20 Mbps per user for large code pulls, CI/CD pipelines, and container image downloads.
• Media production: 50–100+ Mbps per user for video editing, large asset transfers, and rendering.

Remember to account for peak usage rather than average. If 50 users all join a video call at 9 AM, you need enough bandwidth for that simultaneous demand, not just the average across the day. A good practice is to provision 2–3x your calculated average requirement.