Bandwidth Calculator

Bandwidth planning comes up in two distinct scenarios. The first is working out how much total capacity you need to support a number of simultaneous users, each consuming a certain amount of bandwidth: a business sizing an office internet connection, an IT manager planning a VoIP rollout, or a game server host estimating peak load all face this problem. The second scenario is throughput: given a fixed connection speed, how long will it take to transfer a specific amount of data, or given a deadline, how fast does the connection need to be? Both calculations are straightforward but involve the bit-versus-byte conversion that is easy to get wrong. This calculator handles both. In the user bandwidth section, enter the number of concurrent users and the average Mbps each one needs, and you get the total Mbps required and the equivalent in Gbps. In the throughput section, enter a file size in MB and a connection speed in Mbps to get the transfer time in seconds, minutes and hours. Both sections update in real time as you type. The worked examples below use the default values already pre-filled in the inputs.

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User bandwidth

Mbps
500 Mbps
total bandwidth required
In Gbps0.50 Gbps
Per user5 Mbps

Throughput: file transfer time

MB
Mbps
2m 40s
transfer time
Total seconds160
MB per second6.25 MB/s

Results assume sustained theoretical maximum speed. Real-world throughput is typically 60-80% of stated Mbps.

How it works

User bandwidth: total Mbps equals users multiplied by average Mbps per user. Throughput: file size in MB is multiplied by 8 to convert to megabits, then divided by the connection speed in Mbps to get seconds. The time is then formatted as hours, minutes and seconds. The per-second rate is the connection speed divided by 8 to convert from megabits to megabytes.

Worked example

User bandwidth: 100 users each needing 5 Mbps gives 100 times 5 = 500 Mbps total, or 0.50 Gbps. Throughput: a 1,000 MB file at 50 Mbps. 1,000 MB times 8 = 8,000 megabits. 8,000 divided by 50 = 160 seconds, which is 2 minutes and 40 seconds. Transfer rate is 50 divided by 8 = 6.25 MB/s. These match the defaults pre-filled above.

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Frequently asked questions

How much bandwidth do I need for 100 users?

Multiply the number of users by the average bandwidth each one uses at peak time. If each of 100 users needs 5 Mbps, the total is 500 Mbps. In practice, not all users are active at once, so a contention ratio of 50 to 80 percent is often applied for office networks.

What is throughput versus bandwidth?

Bandwidth is the maximum capacity of a connection in megabits per second. Throughput is the actual data transferred per unit of time, which is almost always less than bandwidth due to protocol overhead, latency, congestion and retransmissions. This calculator uses bandwidth as a theoretical maximum for throughput.

How do I calculate the speed needed to transfer 1 GB in 2 minutes?

Convert 1 GB to megabits: 1,000 MB times 8 equals 8,000 megabits. Divide by the time in seconds: 2 minutes is 120 seconds, so 8,000 divided by 120 equals about 66.7 Mbps. This calculator does that arithmetic for you in the throughput section.