The calculator’s purpose
BRAW Planner is a pre-production estimator. It is designed to answer four practical questions: how much storage a planned roll may consume, how long a given card or drive may record, what sustained stream the media must handle, and how much safety capacity a production should allocate.
The output is not a promise that a camera will create an exact byte count. Blackmagic RAW behavior varies by encoding mode, sensor window, camera implementation, firmware, scene detail, embedded audio, metadata, formatting, and filesystem overhead. The tool therefore favors visible assumptions and ranges over false certainty.
Constant Bitrate model
The baseline model starts with the pixel count, a 12-bit data representation, frame rate, the selected compression ratio, and a small container/implementation allowance:
Estimated MB/s = width × height × 1.5 bytes × frames per second × 1.025 ÷ compression ratio ÷ 1,000,000
The 1.025 factor is a practical approximation used to keep modeled rates close to published storage tables across common sensor windows. It is not a specification published by Blackmagic Design. Exact camera tables take priority whenever a production is tied to a specific camera, firmware version, and recording format.
As a validation point, Blackmagic Design’s published 6K 6144 × 3456 rates at 30 fps include 323 MB/s for 3:1, 194 MB/s for 5:1, 121 MB/s for 8:1, and 81 MB/s for 12:1. The model remains close to those values, then scales with the selected frame rate.
Constant Quality ranges
Q0, Q1, Q3, and Q5 are variable-bitrate modes. Image detail can push the rate up or allow it to fall. BRAW Planner models a range relative to the 3:1 baseline, using the following deliberately broad planning factors:
| Mode | Modeled range vs. 3:1 baseline | Planning interpretation |
|---|---|---|
| Q0 | 75%–150% | Highest variable range; size media for the upper bound. |
| Q1 | 50%–120% | Very high quality with substantial scene-dependent movement. |
| Q3 | 33.5%–86% | High-quality middle ground with a meaningful range. |
| Q5 | 20%–50% | More efficient, but still variable with scene complexity. |
These factors are planning approximations, not codec guarantees. The upper result is the more useful value for write-speed and worst-case capacity planning. The lower result helps estimate the possible duration when material is visually simple.
Storage and time formulas
The calculator uses decimal units because storage products are sold in decimal GB and TB:
- Storage in GB = MB/s × duration in seconds ÷ 1,000
- Storage with buffer = base storage × (1 + buffer percentage)
- Record time in seconds = usable GB × 1,000 ÷ MB/s
- Usable capacity = advertised GB × (1 − reserved-capacity percentage)
A 1TB product is treated as 1,000GB. An operating system may display that same byte count as about 931GiB. That display difference is a unit conversion, not 69GB of mysterious lost storage. Formatting and spare-area behavior can reduce truly available recording capacity further.
Drive-speed target
The minimum drive target is the estimated maximum BRAW data rate multiplied by 1.25 and rounded upward to the next 10MB/s. This is a planning headroom figure—not media certification. Sustained writes matter more than an advertised burst speed, and a device can slow down when its cache is exhausted, it gets hot, or it approaches full capacity.
Always cross-check the current approved-media list for the exact camera and recording mode. A mathematically fast drive may still be unsuitable because of cable behavior, controller firmware, power draw, thermal throttling, or compatibility.
Primary references
- Blackmagic Design: Blackmagic RAW overview — encoding behavior, 12-bit workflow, Constant Bitrate, and Constant Quality.
- Blackmagic Design: Pocket Cinema Camera technical specifications — published recording formats and storage-rate tables.
Source pages can change as cameras and firmware evolve. BRAW Planner records the method used here so a future update can revise the model without silently changing the meaning of older estimates.
Known limitations
- The general model does not replace a camera-specific recording table. Resolution and frame-rate choices are independent estimates, not a list of modes supported by every camera.
- Off-speed recording and project frame-rate combinations may behave differently from a simple frame-rate multiplier.
- Constant Quality footage can fall outside a quoted average range.
- Audio, metadata, file splitting, and filesystem allocation add overhead.
- Usable drive capacity and sustained speed are hardware-specific.
If the estimate will affect a paid shoot, run a camera test using the actual camera, firmware, cable, media, sensor window, frame rate, and expected scene complexity. Treat the test as the final authority.