VoIP bandwidth calculator
Work out what your phone system actually needs from your internet connection. Fair warning about where this usually lands: for most businesses the answer is a small fraction of what they already pay for — and that is genuinely useful to know before a provider tells you to upgrade.
Everyone who could pick up a phone, not just the sales team.
A normal office peaks around 25–35%. A sales floor or support desk runs 60–100%.
The default on nearly every business phone system. Best quality, most bandwidth.
- Simultaneous calls
- 3
- Per call
- 87.2 kbps
- Voice traffic alone
- 261.6 kbps
We double the raw figure because voice never has the connection to itself. If that headroom looks trivial next to your internet plan — it usually does — then bandwidth was never your problem, and steadiness is what to check instead.
Where the numbers come from
A voice call sends 50 packets every second — one every 20 milliseconds. On G.711 each packet carries 160 bytes of audio wrapped in 58 bytes of addressing (IP, UDP, RTP, and Ethernet framing). That overhead is why a 64 kbps voice stream needs about 87 kbps of network capacity: more than a third of what a call consumes is envelope rather than letter.
It also explains why compressed codecs save less than their headline suggests. G.729 squeezes the audio from 64 kbps down to 8, but the packet headers do not shrink — so the real saving is 87 kbps to 31, not 64 to 8.
The honest conclusion most calculators avoid
If this tool told you that you need under 2 Mbps and you are paying for 300, bandwidth is not your problem and buying more will not fix a single call. What determines quality on a connection that already has capacity is steadiness — whether packets arrive on time and in order. Test that instead; it takes about ten seconds and it is the measurement that actually predicts how your calls will sound.
Bandwidth questions
How much bandwidth does one VoIP call use?
About 87 kbps in each direction on G.711, the codec most business systems use by default. The voice itself is only 64 kbps — the rest is packet headers, because voice sends 50 small packets per second and each one carries its own addressing. G.729 compresses down to roughly 31 kbps per call at a small cost in audio quality.
How much internet does a 10-person office need for VoIP?
Less than almost anyone expects. Ten people rarely have more than three or four calls running at once, which is about 350 kbps of actual voice traffic — a rounding error on any modern business connection. Double it for headroom and you are still under 1 Mbps. If your calls sound bad, bandwidth is almost certainly not the reason.
Why does the calculator double the number?
Because voice never has the connection to itself. Someone will start a backup, join a video meeting, or upload a large file, and if voice has no headroom it is the traffic that suffers first. Doubling is a simple, safe margin — and turning on QoS so calls get priority matters more than the margin itself.
What percentage of my team is on the phone at once?
For a normal office, plan for 25–35% at peak. A sales floor, support desk, or dispatch operation runs much higher — 60% to nearly 100%. If you are unsure, your current phone system's reports will tell you the busiest hour, and that number is worth more than any rule of thumb.
If I have enough bandwidth, why do my calls still sound bad?
Because call quality depends on steadiness, not speed. A connection can be very fast and still deliver packets late or unevenly, which is what makes calls warble and drop words. Test the connection's consistency rather than buying a faster plan — the fix is usually Wi-Fi or router priority settings, not more megabits.