How this calculator works
Bandwidth planning almost always comes down to the same multiplication: how many things need data at once, times how much data each one needs per second. This calculator covers three common versions of that question — sizing a connection for a number of concurrent users, sizing it for simultaneous video streams, and estimating how much total data a viewing habit adds up to in a month.
A quick reminder on bits versus bytes, since it trips people up constantly: network speeds (Mbps, Gbps) are quoted in bits per second, while file sizes and data caps (GB, TB) are quoted in bytes — and there are 8 bits in a byte. A 50 Mbps connection transfers at most about 6.25 megabytes per second (50 ÷ 8), not 50 megabytes per second. See the download time calculator for the byte-focused version of this same conversion.
The formulas
Concurrent users: required bandwidth = number of users × bitrate per userStreaming: required bandwidth = typical bitrate for the resolution × number of simultaneous streamsMonthly usage: total data = (average bitrate ÷ 8) × seconds watched per day × 30 daysThe streaming bitrates (2.5 / 5 / 8 / 25 Mbps for 480p / 720p / 1080p / 4K) are commonly quoted typical figures, not a fixed standard — actual bitrate varies by codec (H.264 vs. H.265/AV1), frame rate, and how a specific streaming service encodes its video.
Worked example: monthly data from 3 hours a day at 5 Mbps
- Convert the bitrate to bytes per second: 5 Mbps ÷ 8 = 0.625 megabytes per second, or 625,000 bytes per second.
- Convert the daily viewing time to seconds: 3 hours × 3,600 seconds = 10,800 seconds per day.
- Multiply by 30 days in a month: 10,800 × 30 = 324,000 seconds per month.
- Total data: 625,000 bytes/second × 324,000 seconds = 202,500,000,000 bytes = 202.5 GB per month.
Frequently asked questions
Why is my measured internet speed lower than what I pay for?
Advertised speeds are the theoretical maximum; real-world throughput is reduced by protocol overhead, Wi-Fi signal strength, network congestion, and the server on the other end. Many providers only guarantee 70-90% of the advertised speed in practice.
How much bandwidth does a video call need?
Standard-definition video calls typically need around 0.5-1 Mbps per participant, and HD video calls around 1.5-3 Mbps — much less than pre-recorded video streaming, since call video is usually encoded at a lower bitrate and resolution to keep latency low.
Does more bandwidth mean lower latency?
Not directly. Bandwidth is how much data can flow at once (like the number of lanes on a highway); latency is how long a single piece of data takes to arrive (like the speed limit). A high-bandwidth connection can still have high latency, which matters more for gaming and video calls than for streaming or downloads.
Should I plan for average or peak usage?
Plan for peak concurrent usage, not average. A network sized only for the average number of simultaneous users or streams will feel congested every time usage spikes above that average — which, for most shared connections, is often.
How many simultaneous HD video calls can a 100 Mbps connection support?
Around 33 to 66, depending on quality. Using the concurrent-users formula (required bandwidth = number of users × bitrate per user) together with the typical 1.5-3 Mbps range for HD video calls, 100 Mbps ÷ 3 Mbps ≈ 33 calls at the higher-quality end, or 100 Mbps ÷ 1.5 Mbps ≈ 66 calls at the lower end of that range.