A data cap is the monthly limit on how much mobile data you can use before something happens — typically extra charges, automatic top-ups, or throttling to slow speeds.
Common cap levels
- Light: 1-5 GB (basic apps, light browsing)
- Medium: 10-20 GB (some streaming, regular use)
- Heavy: 50-100 GB (lots of streaming, tethering)
- "Unlimited": no cap, but usually with a Fair Use Policy
What uses how much data
- Streaming Netflix in HD: ~3 GB/hour
- Spotify high quality: ~150 MB/hour
- Video calls: ~500 MB/hour
- Browsing: ~50-100 MB/hour
- Email: ~5 MB/hour
What happens at the cap
Most carriers either: (a) auto-charge you for extra bundles, (b) throttle to 2G speeds, or (c) block data entirely until next month. Check your plan.
See also
How Data Cap matters when picking a UK mobile plan
Understanding Data Cap helps you compare mobile providers on a like-for-like basis. Most consumer mobile pricing pages skip the technical detail — knowing the terminology means you can spot when a plan is genuinely better and when it just sounds that way. The Fuse Mobile glossary keeps definitions short and consumer-focused, no jargon-on-jargon.
Fuse Mobile is a UK multi-network data-only eSIM — it gives your phone access to all four UK mobile networks (EE, Three, Vodafone, O2) through a single profile. Where Data Cap is relevant to that setup, it's surfaced explicitly: pricing pages show real numbers, the coverage checker shows live per-network signal, and there's no hidden fee structure. See the plans page for the current pricing or read the multi-network eSIM explainer for the technical detail.