A VoIP call uses much less data than a video call, but it is not free of data cost. If you call regularly on mobile data, it helps to know roughly how many megabytes a conversation uses so that your data plan does not surprise you.
The short answer
As a rough guide, a voice-only VoIP call often uses somewhere between about 0.5 and 1.5 megabytes per minute, depending on the codec and network overhead. That is around 30 to 90 megabytes per hour. These are estimates, and your app and provider may use different settings.
Why the figure varies
Voice is digitised by a codec and sent in small packets. Each packet carries the voice data plus headers that tell the network where to send it. The total is the voice data plus overhead. Commonly cited per-direction figures are:
| Codec | Voice data (per direction) | Approx. including overhead (per direction) | Approx. data for both directions |
|---|---|---|---|
| G.729 | About 8 kbps | About 25 to 40 kbps | About 0.4 to 0.6 MB per minute, 25 to 35 MB per hour |
| G.711 or G.722 | About 64 kbps | About 80 to 95 kbps | About 1.2 to 1.4 MB per minute, 70 to 85 MB per hour |
These numbers come from widely published engineering references and will not match every app exactly. Some apps adapt the codec to network conditions, and silence suppression can reduce usage during pauses.
Calculate your own estimate
- Take the total kilobits per second per direction (for example 87).
- Multiply by 2 because you send and receive at the same time (174 kbps).
- Multiply by 60 for seconds in a minute, then divide by 8 to get kilobytes (about 1,305 KB, or roughly 1.3 MB per minute).
Using this method, 87 kbps works out to about 78 MB per hour. A lighter codec at about 32 kbps works out to about 29 MB per hour.
How many calls fit in a data plan?
If a call averages 1 MB per minute, a 1 GB data allowance would cover roughly 1,000 minutes of calling if you used it for nothing else. In practice, your other apps use data too, so give yourself a margin. If you make long calls often, Wi-Fi is the safer choice.
Ways to reduce data use
- Use Wi-Fi at home or work for long conversations.
- Turn on data saver for other apps so they do not compete in the background.
- Check whether your dialer lets you choose a lower-bandwidth codec. Ask your provider which codecs your account supports.
- Close video apps and downloads before a long call.
Lower-data codecs can sound slightly less natural, so test one before you rely on it. Our codec guide explains the trade-off, and the bandwidth guide helps if several people share the connection.
Worked examples
Using about 1.3 MB per minute as a mid-range figure for a higher-bandwidth codec, and about 0.5 MB per minute for a compressed codec:
| Calling pattern | Higher-bandwidth codec | Compressed codec |
|---|---|---|
| One 20-minute call | About 26 MB | About 10 MB |
| Two 15-minute calls a week, over four weeks | About 156 MB | About 60 MB |
| One hour of calls a day for a month | About 2.3 GB | About 0.9 GB |
These are rounded estimates meant to give you a feel for scale, not exact billing figures. Your real usage can be higher or lower, depending on the app, the codec negotiated and network overhead.
Hidden data use to keep in mind
- Keeping the app registered. The app sends small messages to stay connected. These are tiny compared with calls, but they add up over a month if the app is always running.
- Other apps competing. A background update or video app can use far more data than your calls.
- Roaming. If you travel abroad and use mobile data, roaming charges may apply. Wi-Fi avoids this problem.
How to check your actual usage on Android
- Open Settings and look for Network, Data usage or Connections, depending on your phone.
- Find the app list for mobile data and look for the dialer.
- Note the figure before and after a test call of known length, for example five minutes.
- Divide the difference by the minutes to get your own megabytes-per-minute figure.
This simple test gives a more accurate estimate than any general table, because it measures your own app and settings. Set a data warning in your phone settings if you want an alert before you reach your limit.
If your measured number looks high, check whether the app is using a higher-bandwidth codec, and ask support whether a lower-bandwidth option is available for your account.
Next step: Want to start calling? See the available packages and download the dialer that matches your account.
Frequently asked questions
Does VoIP use data when the app is idle?
Only a small amount to stay registered, though this depends on the app and your settings.
Is VoIP cheaper than a normal call in data terms?
A normal mobile voice call does not use data at all, so the comparison is about your calling costs, not data. VoIP is mainly useful for international calls and for using minutes from your VoIP account.
Does speaking louder use more data?
No. Data use depends on the codec and time, not on volume.
