100 Mbps Filming Record Rate Calculator

Filming Record Time Calculator (Mbps to Storage)

Calculate how much recording time you have available based on your media storage size and your camera's recording bitrate.

The total size of your SD card, CFexpress card, or SSD in Gigabytes.

Your camera codec settings (e.g., 100 Mbps for standard 4K).

function calculateRecordRates() { var storageGBInput = document.getElementById('storageCapacity'); var bitrateMbpsInput = document.getElementById('recordingBitrate'); var resultDiv = document.getElementById('recordRateResult'); var storageGB = parseFloat(storageGBInput.value); var bitrateMbps = parseFloat(bitrateMbpsInput.value); // Handle edge cases and validation if (isNaN(storageGB) || storageGB <= 0) { resultDiv.style.display = 'block'; resultDiv.innerHTML = 'Please enter a valid, positive storage capacity.'; return; } if (isNaN(bitrateMbps) || bitrateMbps <= 0) { resultDiv.style.display = 'block'; resultDiv.innerHTML = 'Please enter a valid, positive bitrate.'; return; } // — The Core Physics/Math Logic — // Key Concept: Bits vs Bytes. 8 Bits = 1 Byte. // Camera rates are MegaBITS per second (Mbps). Storage is GigaBYTES (GB). // 1. Convert Bitrate (Mbps) to Megabytes per second (MB/s) to match storage terminology. var megabytesPerSecond = bitrateMbps / 8; // 2. Convert Storage (GB) to Megabytes (MB). Using binary definition (1024) is safer for actual media capacity. var totalStorageMB = storageGB * 1024; // 3. Calculate total available recording seconds. var totalSeconds = totalStorageMB / megabytesPerSecond; // 4. Convert seconds to readable Hours and Minutes. var hours = Math.floor(totalSeconds / 3600); var remainingSecondsAfterHours = totalSeconds % 3600; var minutes = Math.floor(remainingSecondsAfterHours / 60); // Optional: Calculate accurate minutes if hours is 0 for shorter clips var totalMinutesOnly = (totalSeconds / 60).toFixed(0); // Formatting output strings var timeString = ""; if (hours > 0) { timeString = hours + " Hours & " + minutes + " Minutes"; } else { timeString = totalMinutesOnly + " Total Minutes"; } var requiredWriteSpeed = megabytesPerSecond.toFixed(2); // Display results resultDiv.style.display = 'block'; resultDiv.innerHTML = '

Estimation Results:

' + 'Available Recording Time: ' + timeString + '' + '

---

' + 'Data Rate Check: Your media must sustain a write speed of at least ' + requiredWriteSpeed + ' MB/s.' + 'Note: Actual recording time may vary slightly due to audio tracks, metadata overhead, and how storage manufacturers calculate "GB" (decimal vs. binary).'; }

Understanding Bitrates and Recording Times in Videography

When planning a video shoot, understanding the relationship between your camera's bitrate settings and your available media storage is crucial to ensure you don't run out of space mid-take. This calculator helps DITs (Digital Imaging Technicians), camera operators, and videographers estimate remaining recording time based on common codec bitrates like 100 Mbps.

The Vital Distinction: Megabits (Mb) vs. Megabytes (MB)

The most common confusion in calculating recording times comes from the units used.

• Camera Codecs are usually measured in Megabits per second (Mbps). This refers to the speed of the data stream. A common setting for high-quality 4K video on many mirrorless cameras is 100 Mbps.
• Storage Media (SD cards, SSDs) is measured in Gigabytes (GB) or Terabytes (TB).

To calculate recording time, you must convert these to the same unit. There are 8 bits in every 1 Byte. Therefore, a 100 Mbps data stream is actually writing 12.5 Megabytes of data every second (100 / 8 = 12.5 MB/s).

Why 100 Mbps is a Common Standard

100 Mbps is frequently used as a baseline for high-quality compressed video. It strikes a balance between manageable file sizes and sufficient data for decent color grading in post-production. It is common in codecs like Sony's XAVC S 4K or Panasonic's standard 4K modes.

However, higher-end productions using ProRes RAW or uncompressed formats may use bitrates vastly higher than 100 Mbps, significantly reducing recording times on the same size card.

Media Write Speed Requirements

Besides calculating duration, knowing the Megabyte per second (MB/s) equivalent of your bitrate is essential for choosing the correct memory card. If your camera records at 100 Mbps (which equals 12.5 MB/s), your card must have a sustained minimum write speed higher than that.

For example, a V30-rated SD card guarantees a minimum sustained write speed of 30 MB/s, which is sufficient for a 100 Mbps codec. A V60 or V90 card would be required for significantly higher bitrates.