Bandwidth Requirement Calculator
The bandwidth a site or office needs — from concurrent users, per-user demand, a peak factor and the headroom a link needs to stay responsive.
Raw requirement is users times per-user bandwidth times a peak factor.
How the bandwidth requirement calculator works
Raw requirement is users times per-user bandwidth times a peak factor. The part people miss is that a link should not be sized to its requirement: utilisation above about 70% makes latency climb sharply, because packets start queueing.
So the link you buy is the requirement divided by the utilisation target, not the requirement itself.
Formula: link = users × per-user × peak / utilisation target
Worked examples
| Inputs | Link needed (Mbps) | Note |
|---|---|---|
| 120 users at 2.5 Mbps | 740.57 | about 740 Mbps |
| Video-heavy users | 2,369.83 | over 2 Gbps |
| A full link | 518.4 | no headroom — latency suffers |
FAQFrequently asked questions
How much bandwidth per user?
Ordinary office work is 0.5 to 2 Mbps; video calls 2 to 4; 4K streaming 15 to 25. It depends entirely on what they do.
Why not size the link to the demand?
Because a link at 100% utilisation queues. Latency and jitter climb sharply above about 70%, which users experience as the network being slow even though throughput is fine.
What is a peak factor?
How much busier the busy hour is than the average. 1.5 to 2 is typical; a school at lesson change or an office at 9am is higher.
What is protocol overhead?
Headers, retransmissions and acknowledgements. Around 5 to 10% of raw throughput on typical traffic.
Does this account for bursts?
Only through the peak factor. Genuinely bursty traffic needs buffering or shaping as well as capacity.
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
- Australian Cyber Security Centre — Essential Eight — national guidance on passphrases and system hardening
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.