How much space will your call recordings take?

Recorded calls are the one thing a phone system produces that keeps costing money after the call ends. The size of a single recording is trivial arithmetic. What people get wrong is everything around it: which format the file is actually stored in, whether both sides are kept separately, how many copies exist, and how long the whole pile is kept before anything is deleted. The last of those matters more than the codec, and by a wide margin.

Work out your own

Retention is the input that moves the answer most, and it is the one input this tool has no opinion about. How long call recordings may or must be kept is set by privacy law, by sector rules, by what your contracts say and sometimes by what an individual customer has asked for. Those rules differ by country, by industry and over time, and a calculator that shipped a preset labelled with the name of a statute would be handing out legal advice it is in no position to give.

So the duration buttons above are durations and nothing more. Health, financial and public-sector rules in various countries all point in different directions, and several of the ones people cite most confidently do not actually prescribe a period for call recordings at all. Get your number from whoever advises you on records retention, then put that number in the box and read the size off the page.

What this page can tell you is the consequence. Doubling the window doubles the disk, exactly, and it doubles the monthly bill on either billing basis. If a retention decision is being made on cost grounds, this is the number that decision needs.

One recording is seconds x bits per second / 8, plus the file header. Nothing in that expression is a property of your phone system: a call is a stream of samples, and the only questions are how many samples a second and how many bits each one takes. A five-minute call at 128,000 bits a second is 4,800,000 bytes, and adding the 44-byte header of a canonical PCM WAV changes it by nothing you would notice.

Channels multiply that, and only that. Keeping each side of the conversation on its own channel writes a second stream of samples into the same file, so the file doubles. The call does not get longer. That is why the same decision is free on a provider that bills the recorded minute and costs exactly twice as much on a provider that bills the gigabyte, and it is the clearest demonstration on this page that the two billing bases are not interchangeable.

The stored format is often not the call's codec. A call carried over a compressed codec is routinely written to disk as uncompressed linear PCM, which is where an estimate built on the wire bitrate goes wrong by a factor of sixteen. Cisco's bandwidth table is the source for the codec rates below, and the 40 bytes of IP, UDP and RTP header it adds to every packet are network overhead that never reaches a disk. A storage calculation may take the codec rate from that page and must not take the bandwidth figure.

Then the retention window, which is where the money is. Storage climbs while the window fills and then holds flat, because a window that is actually enforced deletes the oldest recording as a new one arrives. The plateau is the size to buy against. It is a month of recording multiplied by the window in months, then by the number of copies you keep and by whatever margin you want over the estimate.

Gigabytes here are decimal, one billion bytes, because that is the unit storage is billed in. The GiB figure beside it is the one your file manager will show, and it is 7.4% smaller for the same bytes. Neither is wrong; only one of them belongs next to a price.

All of it runs in your browser. There is no endpoint behind this page, no upload and no recording is read: your call volumes and your retention window describe how your business runs, and they are none of ours.

Every bitrate and every price on this page was read off a published page on the date shown, and nothing was written down from memory. Prices in particular move, which is why the calculator takes your rate as an input and these are only here to fill the box with something real.

The rates below are grouped by what they are charged against, and they are not a comparison. Object storage and a voice platform's recording feature are different services doing different amounts of work, and ranking a per-gigabyte rate against a per-minute rate would be a false statement made out of true numbers. Free allowances, per-request charges, rounding and billing periods are named on each row and none of them is modelled.

The 44-byte WAV header is derived rather than quoted: Microsoft's Resource Interchange File Format (RIFF), Microsoft Learn (read 2026-09-07) gives the chunk layout, and 12 bytes of RIFF header plus a 24-byte format chunk plus an 8-byte data chunk header is 44. The page usually cited for the total would not load over TLS on the day this was written, so it is not cited here.

A storage planner that is out by a factor of two still returns a plausible gigabyte figure, and nobody reading it can tell. So the only useful claim is one you can check. The case below was read off the publisher's own page on the date shown, and the right-hand column is this page's arithmetic on the same inputs. The same case is an assertion in node scripts/check-storage.mjs, alongside a second evaluation of the publisher's formula written independently of the model, so the table cannot quietly stop being true.

The check script also holds the model to things no published example covers: that a second channel doubles the bytes and leaves the recorded minutes alone, that a day-by-day simulation with a real deletion queue reaches the same plateau as the closed form, and that several thousand combinations of zero, negative and absurd input produce a named error rather than a number.

It is an estimate of a quantity, not an invoice. Free tiers, charges per request, minimum billable durations, rounding, billing periods, currency and tax are all real and none of them is here. Two of the rates above carry free allowances and separate per-request pricing, both named on the row and neither folded into the arithmetic.

It also assumes a constant bitrate. A variable-bitrate format gives an estimate rather than an answer, and the honest way to use this page for one is to measure a real file, divide its size by its length, and put that figure in as a custom bitrate. That is a measurement of your own system rather than a guess about it.

And it says nothing about who may listen to a recording, what a caller has to be told before one starts, or where the file is allowed to sit. Those are the questions worth more of your time than the disk, and they are covered in what the law asks before you record a call.

Once you know the size

A number on this page is a disk. What decides how much of it you fill is a handful of settings: whether recording is on for everyone or is the choice of the person answering, whether both sides are kept separately, and what happens to a recording when its window runs out. Those are decisions a phone system makes, and they move this figure more than any codec does.