function calculateBurst() {
// Get Input Values
var fps = parseFloat(document.getElementById('fps').value);
var fileSize = parseFloat(document.getElementById('fileSize').value);
var writeSpeed = parseFloat(document.getElementById('writeSpeed').value);
var bufferCap = parseFloat(document.getElementById('bufferCap').value);
// Validation
if (isNaN(fps) || isNaN(fileSize) || isNaN(writeSpeed) || isNaN(bufferCap) || fps <= 0 || fileSize <= 0) {
alert("Please enter valid positive numbers for all fields.");
return;
}
// Calculations
// 1. Data Generation Rate (MB/s)
var dataGenRate = fps * fileSize;
// 2. Net Accumulation Rate (MB/s)
// This is how fast the buffer fills up (Generated – Written)
var netAccumulation = dataGenRate – writeSpeed;
// 3. Total Buffer Size in MB
var totalBufferMB = bufferCap * fileSize;
var timeUntilFull;
var totalShots;
// Check if Card is faster than Camera
if (netAccumulation <= 0) {
// Infinite shooting (Card clears buffer faster than camera fills it)
timeUntilFull = "Unlimited";
totalShots = "Unlimited";
} else {
// Buffer will fill up
// Time = Capacity / Net Fill Rate
var seconds = totalBufferMB / netAccumulation;
timeUntilFull = seconds.toFixed(2) + " sec";
// Total Shots = Time * FPS
// Actually, logical check: The buffer holds 'bufferCap'.
// During the time it takes to fill, we also wrote some images to the card.
// Total Shots = Buffer Capacity + (TimeToFill * (WriteSpeed / FileSize))
// But simpler: Total Shots = TimeToFill * FPS
totalShots = Math.floor(seconds * fps);
}
// 4. Time to clear buffer (if full)
// Time = Total Buffer MB / Write Speed
var clearTime = (totalBufferMB / writeSpeed).toFixed(1) + " sec";
// Display Results
document.getElementById('results-area').style.display = 'block';
document.getElementById('res-time').innerHTML = timeUntilFull;
document.getElementById('res-shots').innerHTML = totalShots;
document.getElementById('res-clear').innerHTML = clearTime;
document.getElementById('res-throughput').innerHTML = dataGenRate.toFixed(1) + " MB/s";
}
Understanding Camera Burst Rate & Buffer Depths
In high-speed photography—such as sports, wildlife, or action journalism—the "burst rate" determines how many frames your camera can capture in a second, but the "buffer" determines how long you can sustain that speed. This calculator helps you simulate the relationship between your camera's speed, file size, and your memory card's performance.
How the Calculation Works
When you hold down the shutter in burst mode, your camera generates data faster than most memory cards can write it. This data is temporarily stored in a high-speed internal memory called the "buffer."
Data Generation: Calculated by multiplying your FPS (Frames Per Second) by the average file size (in MB). For example, 20 FPS at 50MB per file generates 1,000 MB/s of data.
The Bottleneck: Even fast CFexpress cards might only write at 800 MB/s or 1400 MB/s. If your camera generates data faster than the card can write, the buffer begins to fill.
Buffer Saturation: Once the buffer is full, the camera slows down drastically to match the write speed of the card.
Pro Tip: To extend your burst duration, consider shooting in compressed RAW or JPEG formats to reduce file size, or invest in memory cards with a higher sustained write speed (V60, V90, or CFexpress Type B).
Key Metrics Explained
Shooting Speed (FPS): The maximum mechanical or electronic shutter speed your camera is set to.
Avg. File Size: This varies heavily. An uncompressed RAW file from a 45MP camera might be 80MB, while a JPEG might be 15MB. Check your camera settings for estimates.
Card Write Speed: Use the "sustained" write speed, not the "peak" or "read" speed often advertised on the label. Benchmarks often show real-world write speeds are lower than the theoretical maximum.
Buffer Clearing Time: This is the "penalty time" after a long burst where you cannot review images or change certain settings because the camera is busy emptying the buffer to the card.