How much data do you actually need?

Find your real number first

Do not estimate. Your carrier's app shows exactly how much cellular data you used each of the last several months, and that history is the only figure worth planning around. Look at three or four months rather than one, since a vacation or a month without home internet will skew a single reading.

Your phone can also tell you. On iPhone, Settings then Cellular shows usage, though you have to reset the statistics periodically for it to mean anything. On Android, look under Settings then Network and internet then Data usage.

What actually burns data

Rough figures per hour of cellular use, which is enough to sanity-check your number:

• Music streaming: roughly 50 to 150MB per hour.
• Standard-definition video: roughly 0.5 to 1GB per hour.
• High-definition video: roughly 2 to 3GB per hour.
• Video calls: roughly 0.5 to 1.5GB per hour.
• Social scrolling with autoplay video: roughly 0.5 to 1GB per hour.
• Messaging, email, maps, and web browsing: small enough that they rarely drive a bill.

The Wi-Fi factor is the whole game

Cellular data only counts when you are off Wi-Fi. If you are on home Wi-Fi in the evening and office or campus Wi-Fi during the day, your cellular usage is limited to commutes and errands, which is why so many people land under 10GB without trying.

The people who genuinely need large allowances are those without reliable home internet, those who commute long distances streaming video, and those who tether a laptop regularly.

Rough tiers

Once you know your number, it maps cleanly onto plan shopping:

• Under 5GB a month: a small fixed-data plan will save you a lot, and unlimited is wasted money.
• 5 to 15GB: the sweet spot for budget brands and mid-tier plans. Most people live here.
• 15 to 30GB: worth comparing a large fixed plan against entry-level unlimited.
• Over 30GB, or heavy hotspot use: unlimited genuinely earns its price, and the high-speed threshold below starts to matter.

Unlimited is not unlimited

Nearly every unlimited plan has a high-speed threshold, often somewhere between 30GB and 100GB. Past it, the carrier may slow you sharply for the rest of the billing cycle, and cheaper unlimited plans have lower thresholds.

Separately, budget brands are deprioritized when a tower is congested, regardless of how much data you have used. So there are two different slowdowns to understand: hitting your own threshold, and sharing a busy tower.

Hotspot is counted separately

Tethering a laptop or tablet usually draws from a distinct hotspot allowance, and it is often much smaller than the phone's data allowance. Some plans include only a few gigabytes of high-speed hotspot, and some include none at all while still calling themselves unlimited.

If you tether regularly, treat hotspot as its own requirement rather than assuming unlimited covers it.