How much data does messaging really use?
If you've ever run out of data halfway through the month, you've probably wondered where it went. Text messages are almost never the answer. The data goes on photos, videos, calls and things your apps do quietly in the background. This guide explains the units, what each kind of message costs, and how to make a small plan last.
First, the units
- 1 kilobyte (KB) = 1,000 bytes. A short text message is a few hundred bytes of actual words.
- 1 megabyte (MB) = 1,000 KB.
- 1 gigabyte (GB) = 1,000 MB, or 1,000,000 KB.
Phones and operators sometimes use 1,024 instead of 1,000. The difference is about 2 to 7 percent and doesn't change the big picture.
Call speeds are often quoted in kilobits per second (kbps) rather than kilobytes. There are 8 bits in a byte, so 160 kbps is 20 KB per second. When a figure looks suspiciously low or high, check whether it's bits or bytes.
What each kind of message costs
Text messages
The words in a typical chat message are tiny, well under a kilobyte. What the app adds around the words decides the real cost: encryption, delivery receipts, typing indicators and link previews. A link preview that fetches an image can cost far more than the message itself.
Photos
A photo straight from a modern phone camera is often several megabytes. Messaging apps shrink photos before sending, but how much varies a lot. Some keep them large for quality; others compress hard. Photos are usually the single biggest everyday data cost in a busy group chat, especially if your app downloads every photo automatically.
Voice messages
Voice notes are compressed audio. Depending on the app and quality, a minute of voice is typically tens to a few hundred kilobytes. That's far more than typing the same words, but far less than a video.
Video
Short videos are the heaviest thing most people send or receive. Even compressed, a 30-second clip can run to several megabytes, and autoplaying videos in chats or status feeds can use data without you choosing to watch.
Calls
A call uses data in both directions for as long as it lasts. Voice calls are fairly light. Video calls are much heavier, and in high quality can use many megabytes a minute. Many apps adjust quality automatically, which is convenient on Wi-Fi but can surprise you on mobile data. A call app that lets you choose quality, and shows what the call is using, puts you in control.
What quietly eats your plan
- Auto-download of media. Every photo and video in every group downloads whether you look at it or not.
- Autoplay. Videos in chats, stories and feeds start playing on their own.
- Background sync and backups. Chat backups to the cloud can be large, and some run on mobile data unless you tell them not to.
- App updates. One app update can be bigger than a month of texting.
- Stickers, GIFs and link previews. Small each time, but they add up in busy chats.
Working it out: what does 1 GB buy?
A quick way to compare is to divide your allowance by the size of each item. Here are the figures for WhisperLite, our own messenger, which publishes its sizes: under half a KB per text, about 60 KB per squeezed photo, about 50 KB per minute of voice message, and Data saver calls capped at 20 KB a second.
| With 1 GB you could send… | Working | Roughly |
|---|---|---|
| Text messages | 1,000,000 KB ÷ 0.5 KB | Over 2 million |
| Photos | 1,000,000 KB ÷ 60 KB | About 16,600 |
| Minutes of voice messages | 1,000,000 KB ÷ 50 KB | About 20,000 (333 hours) |
| Data saver call time | 1,000,000 KB ÷ 20 KB/s | About 14 hours |
You can do the same sum for any app. Send a few photos or make a short call, then check the app's data use in your phone's settings and divide.
How to check what your apps use
- Android: Settings → Network & internet (or Connections) → Data usage → Mobile data usage. The wording varies by phone maker.
- iPhone: Settings → Mobile Data (or Cellular). Scroll down to see each app.
Reset the counter at the start of each billing period, or at the start of a trip, so the numbers mean something.
Five quick wins
- Turn off automatic media download on mobile data in each messaging app.
- Turn off autoplay for videos and GIFs.
- Set chat backups and app updates to Wi-Fi only.
- Use a lower call quality, or voice instead of video, when you're on a small plan.
- Check per-app data use once a week until you know your habits.
Travelling or working at sea? See how to save mobile data at sea and abroad for more.
Built for this: WhisperLite is a messenger designed around small data plans. Photos only download when you tap them, and calls let you choose what you spend.