Bandwidth Calculator

Works out roughly how much bandwidth an office, school, or cloud environment actually needs based on user count, per-user usage, and contention ratio — so you're not overpaying for capacity nobody uses, or underpaying and getting the "the internet is slow" ticket every Monday morning.

Contention ratio, in plain terms

A contention ratio describes how many users are sharing a fixed amount of bandwidth. 1:1 means everyone gets their full allocation simultaneously — that's a dedicated leased line, and it's priced like one. 1:20, typical of residential broadband, means 20 people share the same capacity on the assumption they're not all maxing it out at once. That assumption is fine for a household; it's a much riskier bet for a business that needs consistent performance during a specific window every day.

• 1:1 — leased line, SLA-backed, guaranteed bandwidth at all times
• 1:5 — reasonable for business-critical office connectivity
• 1:10 — acceptable for general office use with mixed traffic
• 1:20–1:50 — consumer-grade, not something you'd want backing an SLA

Roughly what each thing on your network actually costs you

• Web browsing / email — 1–5 Mbps per user
• Video calls (Teams, Zoom) — 3–8 Mbps per user at 1080p
• VoIP — around 0.1 Mbps per active call, small individually but adds up on a busy switchboard
• 4K streaming — ~25 Mbps per stream
• Background cloud backup — 10–50 Mbps depending on volume, and it's the one that quietly eats headroom nobody budgeted for

Leave yourself room

Add 30–40% headroom on top of the calculated requirement for spikes, updates, and cloud sync jobs that decide to run at the worst possible moment. A link running consistently above 80% utilisation is going to show congestion and packet loss whether or not the raw throughput number technically "covers" your traffic — and if VoIP or video matters on that link, QoS to prioritise it over bulk transfers is worth setting up before you need it, not after the first dropped call.