How Much Mobile Data a Voice Call Actually Uses

The short answer

An internet voice call uses between 0.25 and 0.5 MB per minute, which is 15 to 30 MB per hour. A one-hour call therefore costs about the same amount of data as loading fifteen ordinary web pages, or about one minute of high-definition video.

That figure surprises people, and the surprise is worth correcting because it changes behaviour. Voice is the cheapest thing you can do with a data connection. Anyone rationing a mobile allowance should be rationing video, photos and app updates, not phone calls.

Data per minute, by codec

The exact number depends on the codec — the algorithm that compresses your voice for transmission. Every figure below includes IP, UDP and RTP header overhead, which is roughly 40 bytes on every packet and adds about 20 kbps at the standard packet rate. Overhead is not a rounding error at these bitrates, and figures that omit it understate real usage by a third or more.

Codec	Payload bitrate	With overhead	Per minute	Per hour	Where you meet it
Opus (voice mode)	16–24 kbps	~40 kbps	~0.30 MB	~18 MB	WhatsApp, Signal, most modern apps
G.729	8 kbps	~32 kbps	~0.24 MB	~14 MB	Older business VoIP systems
G.711 (μ-law/A-law)	64 kbps	~87 kbps	~0.65 MB	~39 MB	Calls to landlines and mobiles
AMR-WB (VoLTE)	12.65 kbps	~30 kbps	~0.23 MB	~14 MB	Carrier calls over 4G/5G

Two things follow from this table.

Calls to real phone numbers use more data than app-to-app calls. A call that ends on the public telephone network is usually carried in G.711 for at least part of its path, because that is what the telephone network speaks. The practical figure for a call to a landline or mobile is around 0.5 to 0.65 MB per minute rather than 0.3.

Both directions count. The figures above are per direction. If your carrier meters upload and download separately and you are looking at a total, a one-hour call moves roughly double the per-direction number — though most consumer plans meter a combined total, in which case the per-hour figures above already reflect what you will be billed for one side of a conversation.

What that means for a real month

Concrete numbers are more useful than rates.

• A 10-minute call every day for a month: about 100–200 MB.
• A 30-minute call home every Sunday: about 60–80 MB a month.
• An hour a day, every day: about 0.5–1 GB a month.

Against a typical modern allowance, even the heaviest of those is a small fraction. For comparison, a single hour of streaming video at 1080p is roughly 3 GB — more than an entire month of daily hour-long voice calls.

If you are on a very small plan or a pay-per-megabyte roaming rate, the arithmetic still favours voice heavily. Ten minutes of talking is a quarter of a megabyte per minute; ten minutes of scrolling a social feed with autoplaying video is tens of megabytes.

Does a video call use much more?

Yes — between twenty and a hundred times more. A video call is a voice call with a video stream attached, and the video stream dominates completely.

Call type	Typical per minute	Per hour
Voice only	0.3 MB	~18 MB
Video, low quality	4–6 MB	240–360 MB
Video, standard	8–12 MB	480–720 MB
Video, HD	20–30 MB	1.2–1.8 GB

The practical consequence when data is scarce: turning the camera off is the single largest saving available on a call, and it is larger than any other adjustment you can make. Most apps let you disable video mid-call and drop straight to the voice figures above.

Does Wi-Fi calling use my mobile data allowance?

No. Wi-Fi calling routes the call over the Wi-Fi network's internet connection, so it consumes the Wi-Fi network's data — the home or hotel broadband — and not your mobile plan's allowance.

What it may consume is your carrier's minutes, and that distinction catches people out. Carrier Wi-Fi calling, the feature built into iOS and Android that hands your normal phone calls to a Wi-Fi network, is still a carrier call: it is billed as a call under your plan, including international rates if you dial abroad. It saves you cellular signal, not money.

A third-party VoIP app on the same Wi-Fi is a different thing. It is not a carrier call, it does not touch your minutes, and it is billed by the app at its own rate — which is the reason people use one to call abroad. See WiFi calling explained for the difference in detail.

Does a call use data while nobody is speaking?

Usually less, and sometimes almost none. Most modern codecs implement voice activity detection with comfort noise generation: when the microphone detects silence, the encoder stops sending full audio frames and sends a much smaller descriptor of the background noise instead, which the far end reproduces so the line does not sound dead.

In a typical conversation each party speaks about 40% of the time, so voice activity detection can cut real usage well below the theoretical maximum — often by a third. The figures in the first table are the continuous-speech numbers, which is the right way to quote them: they are an upper bound you will rarely exceed.

How to check your own usage

You do not have to trust any of these numbers. Both major mobile platforms report per-app data consumption directly.

On iOS: Settings → Cellular, then scroll to the app list. Each app shows its cellular data total for the current period. Reset the statistics before a test call to get a clean measurement.

On Android: Settings → Network & internet → Internet → the gear icon next to your carrier → App data usage. Select a date range and an app.

Make a five-minute call, check the figure, and divide. That gives you the real number for your app, your codec and your network, which beats any table including this one.

Does an app use data when you are not on a call?

Yes, a small and steady amount, and it is worth knowing because it is the part people cannot account for.

A calling app that can receive calls has to stay reachable. It maintains a registration with its server and sends a keepalive packet every 30 to 60 seconds so the network's NAT table does not forget the connection. Each keepalive is tiny — tens of bytes — but running continuously it adds up to a few megabytes a month.

Push notifications reduce this considerably and are why modern apps do not drain a battery keeping a socket open: the app registers with Apple's or Google's push service, and the operating system maintains a single shared connection for every app on the device. An incoming call arrives as a push, which wakes the app.

An app that only makes outbound calls, as Telvio does, has less of this overhead again — there is no inbound registration to maintain. In practice, background data for a calling app is under 5 MB a month on any of these designs, which is smaller than the measurement error on most carrier reporting.

How to reduce data use on a call

If you are genuinely rationing data, four adjustments in descending order of effect.

1. Turn the camera off. Worth 95% of the total on a video call. Nothing else comes close.
2. Use voice notes instead of live calls where the conversation does not need to be live. A 60-second voice note is roughly 100 KB — a third of what the same minute costs live, because it is compressed as a file rather than streamed in real time.
3. Avoid re-dialling on a bad connection. Each failed attempt costs the setup exchange and whatever audio played before it dropped. If a call is failing repeatedly, fix the connection rather than retrying — see call quality troubleshooting.
4. Do not bother disabling HD audio. The saving between a wideband and narrowband voice codec is a few megabytes an hour, and you pay for it in intelligibility, which tends to make calls longer.

What about data roaming?

Abroad, the same figures apply but the price per megabyte can be wildly different, so the arithmetic is worth doing explicitly.

At a punitive roaming rate of, say, $10 per megabyte, an hour of voice calling at 18 MB would cost $180 — absurd, and the reason nobody should call over a metered roaming connection at those rates. At a typical travel-package rate of a few dollars per gigabyte, the same hour costs a few cents.

The practical rule when travelling: use Wi-Fi for calls where it exists, and check your roaming rate per megabyte before using mobile data for anything at all. The difference between a bundled travel package and default pay-as-you-go roaming is routinely three orders of magnitude, and it is the single largest avoidable cost in international communication. Avoiding roaming charges covers the alternatives.

Does poor signal increase data usage?

Slightly, and in a way that is worth knowing. On a weak connection, lost packets are sometimes retransmitted and some codecs add forward error correction — extra redundant data sent specifically so the far end can reconstruct what got lost. Opus does this and it can raise the effective bitrate by 20 to 30% on a lossy link.

So a bad connection uses somewhat more data and sounds worse at the same time. If a call is sounding robotic or choppy, that is packet loss, and the codec is already working harder in response.

Bottom line

A voice call over the internet costs about 0.3 MB per minute app-to-app, and about 0.5 to 0.65 MB per minute when the call ends on a real phone number in G.711. An hour of talking is 15 to 40 MB — less data than a minute of HD video.

Video is the expensive thing, at 240 MB to 1.8 GB per hour depending on quality, so turning the camera off saves more than every other adjustment combined. Wi-Fi calling spends the Wi-Fi network's data rather than your mobile allowance, but carrier Wi-Fi calling still spends your plan's minutes and its international rates. And if you want a number you can trust rather than an average, make a five-minute call and read the per-app figure your phone already records.