How do I calculate video file size from bitrate?

Multiply the total bitrate by the duration, then divide by eight to turn bits into bytes. A 90-minute service at a combined 6,000 kbps works out at roughly 4 GB. The arithmetic is simple; the part people get wrong is forgetting the audio track, which adds its own bitrate on top of the video.

What bitrate should a church livestream use?

For 1080p at 30 frames per second, 4,500 to 6,000 kbps is the usual range, with 128 to 192 kbps for audio. At 720p, 2,500 to 4,000 kbps is enough. Motion is what drives the number — a static pulpit shot survives a low bitrate that a moving worship set would fall apart at.

How much upload speed do I need to stream?

Plan on roughly double your stream bitrate as sustained upload, and measure it at the time of day you actually stream rather than on a quiet Tuesday. A 6,000 kbps stream wants about 12 Mbps of headroom. The reason for the margin is that a church network is rarely doing only one thing — the same connection is carrying phones, the office and the guest wifi.

Why is my recorded file so much bigger than the stream?

Local recordings are usually written at a higher bitrate than the one you send out, because there is no network to protect. Some software also records a separate high-quality master alongside the stream. That is desirable — the recording is the copy you will cut clips from later, and the stream is the compressed version the internet saw.

Does a higher bitrate always look better?

Only up to the point where the encoder stops discarding anything you can see. Past that you are spending bandwidth and storage for no visible gain, and on an unreliable connection a bitrate set too high looks far worse than a modest one, because dropped frames are more noticeable than soft detail.

Video bitrate and file size calculator

Bitrate to file size, file size to bitrate, and the upload speed a Sunday stream really needs.

Runs in your browser — free, no signup, nothing uploaded

Church livestream presets

Video bitrate (kbps)Audio bitrate (kbps)

Duration — hoursDuration — minutes

File size

4.18 GB

6,192 kbps combined for 1 hr 30 min.

Sustained upload recommended: 12.4 Mbps — roughly double the stream bitrate, because a church network is never carrying only the stream.

What that bitrate means in practice
Hours that fit on a 64 GB card	23 hr
Size of a typical 90-minute service	4.18 GB
Size at your entered duration	4.18 GB

The formula, and the track everyone forgets

File size is bitrate times duration, divided by eight to turn bits into bytes. That part is arithmetic. What trips people up is that a video file carries two bitrates, not one — a video track and an audio track running alongside it — and most back-of-envelope math only accounts for the first. Leave out a 192 kbps audio track on a 90-minute service and the estimate comes in noticeably short, which is exactly the gap between “why is this file bigger than I expected” and a calculation that actually matches what lands on disk.

One more thing worth saying plainly: a “GB” here is 1,000 MB, the decimal definition your camera and streaming box both use internally. Some operating systems report file sizes in binary gibibytes instead, which is why the same file can read as a slightly different number depending on where you check it. Neither reading is wrong; they are just different units wearing the same abbreviation.

Choosing a bitrate for a church stream

Motion is what drives the number, not resolution alone. A static wide shot of a pulpit barely changes from frame to frame, so the encoder has almost nothing new to describe and a modest bitrate holds up fine. A worship set with three moving cameras, stage lighting shifting color and a crowd swaying is the opposite case — the same resolution at the same bitrate will show compression artifacts the pulpit shot never would. If your service moves between the two, size the bitrate for the busier segment, not the calmer one.

This is also why a preset is a starting point and not a rule. A single fixed camera on a preacher can often drop a notch below the presets above and look identical to a viewer; a multi-camera production with graphics and lower-thirds usually wants to sit at or above them.

Upload headroom, measured on the day it matters

The doubling in the result above is not a superstition — it is the gap between what a connection can do on paper and what it can sustain while also doing everything else a building does on a Sunday morning. Guest wifi, a dozen staff phones, a background system sync and the stream itself are all fighting for the same pipe, and internet providers advertise a peak number that assumes nothing else is happening. A speed test run on a quiet Tuesday afternoon tells you almost nothing about 10:58 on Sunday. Test it during the actual service, or during a dry run at the same time of day and the same day of the week, if you want a number you can trust.

Where more bitrate stops helping

Past a certain point, the encoder has already captured everything a viewer can perceive, and additional bitrate is spent describing detail nobody will notice was ever missing. That ceiling is lower than most people assume for a talking-head shot, and higher for a visually busy one — which is the same motion principle from above, working in the other direction.

On an unreliable connection, pushing bitrate higher can actively make the stream look worse, not better. A setting your upload can't sustain doesn't fail gracefully — it drops frames and stalls the buffer, and a viewer notices a frozen frame or a stutter far more than they would ever notice slightly softer detail. If a stream is struggling, the fix is almost always to lower the bitrate to something the connection can hold steady, not to raise it and hope.

Questions people ask

How do I calculate video file size from bitrate?: Multiply the total bitrate by the duration, then divide by eight to turn bits into bytes. A 90-minute service at a combined 6,000 kbps works out at roughly 4 GB. The arithmetic is simple; the part people get wrong is forgetting the audio track, which adds its own bitrate on top of the video.
What bitrate should a church livestream use?: For 1080p at 30 frames per second, 4,500 to 6,000 kbps is the usual range, with 128 to 192 kbps for audio. At 720p, 2,500 to 4,000 kbps is enough. Motion is what drives the number — a static pulpit shot survives a low bitrate that a moving worship set would fall apart at.
How much upload speed do I need to stream?: Plan on roughly double your stream bitrate as sustained upload, and measure it at the time of day you actually stream rather than on a quiet Tuesday. A 6,000 kbps stream wants about 12 Mbps of headroom. The reason for the margin is that a church network is rarely doing only one thing — the same connection is carrying phones, the office and the guest wifi.
Why is my recorded file so much bigger than the stream?: Local recordings are usually written at a higher bitrate than the one you send out, because there is no network to protect. Some software also records a separate high-quality master alongside the stream. That is desirable — the recording is the copy you will cut clips from later, and the stream is the compressed version the internet saw.
Does a higher bitrate always look better?: Only up to the point where the encoder stops discarding anything you can see. Past that you are spending bandwidth and storage for no visible gain, and on an unreliable connection a bitrate set too high looks far worse than a modest one, because dropped frames are more noticeable than soft detail.