Bandwidth Calculator
How much bandwidth a group of simultaneous users, video streams or calls actually needs — with headroom, so the connection does not saturate at the busiest moment.
Required bandwidth is the number of concurrent users multiplied by what each one consumes, plus headroom.
How the bandwidth calculator works
Required bandwidth is the number of concurrent users multiplied by what each one consumes, plus headroom. The concurrency figure matters more than the headcount: an office of 100 people rarely has 100 simultaneous streams. Headroom exists because a link at 100% utilisation queues packets and latency climbs sharply — the usual planning target is 70–80% of capacity at peak.
Formula: required = concurrent users × per-user rate ÷ target utilisation
Worked examples
| Inputs | Bandwidth needed | Note |
|---|---|---|
| 50 users, 40% active, 5 Mbps each | 133.3 Mbps | 20 concurrent × 5 = 100 Mbps raw, 133 with headroom |
| A 4K streaming household | 125 Mbps | 125 Mbps |
| 200-seat office, 30% on video calls | 257.1 Mbps | about 257 Mbps |
FAQFrequently asked questions
How much bandwidth per user do I need?
Roughly: 1 Mbps browsing, 3 Mbps a video call, 5 Mbps HD video, 25 Mbps 4K. Multiply by how many are active at once, not by the headcount.
What is a sensible concurrency figure?
In offices 30–50% at peak is typical; in a home nearly everyone online is active at once.
Why not plan for 100% utilisation?
A saturated link queues packets, so latency and jitter rise sharply and calls break up before the throughput number looks bad. Plan for 70–80%.
Does upload matter too?
Yes, for video calls and backups, which are far more upload-heavy than browsing. Run the calculator again with your upload figures.
Is Wi-Fi the bottleneck?
Often. The shared radio, not the internet connection, is usually what limits a busy office or home.
Where these figures come from
- IEC 80000-13 — Information science and technology (quantities and units) — the decimal (kB, MB) versus binary (KiB, MiB) prefixes used throughout
- RFC 4632 — Classless Inter-domain Routing (CIDR) — the address-plan arithmetic behind the subnet calculator
- RFC 1918 — Address Allocation for Private Internets — the private ranges the subnet calculator recognises
- NIST SP 800-63B — Digital Identity Guidelines, Authentication — length over composition rules; the basis of the password guidance here
- NIST SP 800-57 Part 1 — Recommendation for Key Management — key-strength comparisons used by the key-space calculator
- National Cyber Security Centre — password guidance — UK national guidance on password policy
Last checked: September 2026. Units follow the SI decimal convention (IEC 80000-13 defines the binary alternatives); network and security figures cite the defining standard.