How to save mobile data when watching video

5 min read

Video is, by far, what uses the most data on a phone. An afternoon of watching videos away from home can eat up a good chunk of your monthly plan. With a simple calculation and a few settings, you can find out how much you’re using and keep it under control, whatever app you use.

How much data a video uses: the math

What a video uses depends on its bitrate, the amount of data per second, measured in megabits per second (Mb/s). To convert it to megabytes, the unit your plan uses, divide by 8, because a byte is 8 bits:

Megabytes per minute = Mb/s × 60 ÷ 8.
Megabytes per hour = Mb/s × 3,600 ÷ 8, which is the same as Mb/s × 450.

An example: a video at 2 Mb/s uses 2 × 450 = 900 MB per hour, almost a gigabyte. One at 8 Mb/s uses 3,600 MB per hour, over three and a half gigabytes. Audio alone is much lighter: a radio station at 128 kb/s (0.128 Mb/s) comes to about 58 MB per hour.

In Whatplay you can see the bitrate of what’s playing in the player’s “Options”: under the title you’ll find the resolution, the codec and the Mb/s, when the video provides them. Resolution and data use aren’t the same thing, because a heavily compressed 1080p video can use less than a lightly compressed 720p one; but, in general, the higher the resolution, the more data.

Get a warning before you use data

Turn on Settings › Player › “Warn me when using mobile data”. With it on, Whatplay asks you before playing something from the internet without Wi-Fi (“You’re using mobile data”), and you choose whether to continue. If you were watching something with the screen off or in the picture-in-picture window and your phone switches from Wi-Fi to mobile data, it stops playback and lets you know with a notification so you can decide whether to carry on. It’s very handy when you leave home with something playing. The help sums it up in Does it use a lot of data?

What downloads in the background

It’s not just video that uses data. Lists and TV guides are downloaded too, and some of them are tens of megabytes:

In Settings › Lists, “Update lists when the app opens” downloads the lists that have an address again if more than an hour has passed since the last time, and “Update each list when you open it” does so if more than ten minutes have passed. If your lists are large and you often open the app away from home, consider turning these off and updating manually with “Refresh”, in the list’s menu.
Each list also has its own “Auto-sync” in its menu, in case you only want to turn it off for one of them.
XMLTV guides refresh from time to time, but if they haven’t changed, they aren’t downloaded again.
Sync with Google Drive moves very little: large lists travel with just their address.

Android’s own settings

Data Saver: in Android’s network settings, it limits what apps download in the background over mobile data.
Data warning and limit: Android can warn you when you reach one amount and cut off data when you reach another. Set them a little below what your plan includes.
Usage per app: in the same section you’ll see how much data each app has used in the period. It’s the most reliable way to find out what’s eating up your data.

The exact names of these menus vary depending on the phone’s manufacturer and the Android version.

Habits that save data

Long stuff on Wi-Fi. Save movies for home and use your data for short things.
What’s already on your phone uses no data. Videos saved on the device are in the Media tab and don’t touch the network.
Look for lighter versions. If the source offers the same video in several separate qualities, use the lowest one when you’re out. With HLS or DASH, the player chooses the quality based on network speed, not on your plan; we explain it in HLS and DASH.
For listening, choose audio. A podcast or a radio station uses a fraction of what a video does.
The picture-in-picture window and the screen-off mode still download video. If you’re only going to listen, an audio version is better.
A moderate buffer. In Settings › Player › “Buffer”, a low value means that if you close a video halfway through, you’ll have downloaded less that you didn’t need.

Careful when sharing your connection

If you turn on your phone’s hotspot to connect a TV or a computer, everything you watch on them comes out of your mobile data. The same goes for WebCast if you use your phone’s hotspot: the phone downloads the video with its data and passes it on to the TV. With Chromecast and your home Wi-Fi, on the other hand, it’s the TV that downloads the video, over your home broadband.

A practical example

Say you have a 20 GB monthly plan and videos at around 3 Mb/s. Each hour comes to 3 × 450 = 1,350 MB, so the plan covers almost 15 hours of video, not counting anything else. If you drop to a 1.5 Mb/s version, the same time costs half as much. Doing this math once helps you decide what to watch away from home and what to save for Wi-Fi. And if the video also keeps stopping, see dropouts, stuttering and slow loading.