Recording storage calculator

Hours rolling, not show length

The number people get wrong is not the codec. It is the duration. A show that runs ninety minutes is a call where cameras roll through soundcheck, rehearsal, a walk-through, and then the show, and nobody stops recording between them because the one time you do is the time you miss something.

Budget for the call, not the run of show. If the schedule says load in at seven and doors at six, the cameras are rolling for more of that day than anyone plans for.

Capacity is not the constraint. Sustained write is.

A card has two numbers that matter and the box only advertises one of them. Capacity is on the front in large type. Sustained write speed is in the datasheet, it is lower than the peak read speed printed next to it, and it is the one that decides whether you drop frames.

ProRes 422 HQ at 4K runs 707 Mbps, which is about 89 MB/s that has to land every second with no dips. Plenty of cards advertise numbers well above that and cannot hold it under heat after forty minutes in a camera under stage lighting. Buy for sustained write, and buy the brand your camera vendor actually qualified.

Two places before anybody formats anything

The calculator sizes your cards. Size the backup drive for twice it. Footage lives in two places before a card gets formatted, and that rule does not bend for a tight turnaround or a client standing behind you asking for the file. A card is not a backup of itself.

If you are streaming the same event, the upload side has its own arithmetic and it is a different constraint entirely. That is the bandwidth calculator.

Common questions

How much storage does one hour of ProRes 422 use?

About 53 GB an hour at 1080p and 212 GB an hour at 4K, at roughly 30fps. ProRes 422 HQ is heavier: 79 GB an hour at 1080p and 318 GB at 4K. Multiply by your camera count, then by two if you are recording redundantly to both card slots.

How do I work out storage for a multi-camera shoot?

Take the codec's bitrate in Mbps, divide by 8 for megabytes per second, multiply by 3600 for an hour, and divide by 1000 for decimal GB. Then multiply by cameras and by hours rolling. The mistake people make is using show length instead of hours rolling: cameras run through rehearsal, and a four hour call is rarely a four hour show.

Why does my card drop frames even though it has space?

Capacity and sustained write speed are different specifications. A codec at 707 Mbps needs about 89 MB/s sustained, every second, with no dips. Cards advertise a peak read speed on the front and a lower sustained write speed in the datasheet, and a card that cannot hold the write rate drops frames regardless of how much room is left on it.

Should I size drives in GB or GiB?

Decimal GB, because that is how cards and drives are sold. A card sold as 1TB holds 1000 GB by the manufacturer's arithmetic, not 1024. Sizing a shoot in GiB and buying in GB is a reliable way to end the day one card short.