Axis Bitrate Calculator: How to Set It

The Axis bitrate calculator on this page works out the recommended video bitrate for an Axis network camera based on the resolution, frame rate, and compression level you plan to use. You enter the camera’s resolution in megapixels, the frame rate in fps, and the H.264/H.265 compression quality, and it returns a suggested bitrate in Mbps along with the estimated daily storage requirement. This gives you a practical starting point for configuring your camera’s stream settings or planning your network and recording capacity.

Formula

The calculator uses a simple rule-of-thumb formula that is common in the IP camera industry:

Bitrate (Mbps) = Resolution (MP) × Frame Rate (fps) × Quality Factor × 0.07

• Resolution (MP) – the sensor resolution in megapixels (e.g., 2 MP for 1920×1080, 4 MP for 2560×1440, 8 MP for 3840×2160).
• Frame rate (fps) – the number of frames per second the camera records (typically 5–30).
• Quality factor – a multiplier that reflects the compression level: 0.5 for low quality, 1 for medium, 2 for high. H.265 generally achieves the same quality at roughly half the bitrate of H.264, so the factor is halved for H.265.
• 0.07 – an empirical constant that approximates the bitrate per megapixel per frame per second for typical surveillance scenes. It is derived from observed H.264 bitrates in real-world installations.

The storage calculation is then: Storage (GB/day) = Bitrate (Mbps) / 8 × 86400 / 1000. This converts bits to bytes (÷8), seconds per day (86400), and bits to gigabits (÷1000) to get gigabytes.

Worked Example

Using the default values from the calculator: a 4 MP camera at 15 fps with medium H.264 compression (quality factor = 1).

1. Bitrate = 4 × 15 × 1 × 0.07 = 4.2 Mbps
2. Storage per day = (4.2 / 8) × 86400 / 1000 = 0.525 × 86.4 = 45.36 GB/day

The calculator rounds the bitrate to 4.2 Mbps and the storage to 45.4 GB/day. This matches the output of the block above.

Why Bitrate Matters for Axis Cameras

Axis Communications is a major manufacturer of network cameras, and their cameras support H.264 and H.265 compression. Setting the right bitrate is a balance: too low and the image becomes blocky or blurry, especially with motion; too high and you waste bandwidth and storage. Axis cameras allow you to set a fixed bitrate or use variable bitrate (VBR) with a target average. The calculator gives you a sensible target for that setting.

For example, a 4 MP camera at 15 fps is a common configuration for retail or office surveillance. At medium quality, 4.2 Mbps is a reasonable target. If you set the bitrate to 2 Mbps, you might see artifacts when people move quickly. If you set it to 8 Mbps, you’ll use nearly double the storage for little visible improvement.

How to Choose the Right Bitrate

Start with the calculator’s suggestion, then adjust based on your scene:

• Static scenes (empty corridors, parking lots at night): you can lower the bitrate by 20–30%.
• High-motion scenes (busy intersections, retail floors): increase by 20–30%.
• Facial identification: use higher quality (factor 2) and a higher frame rate, but note that bitrate alone doesn’t guarantee identification – the lens and lighting matter more.
• Forensic detail: if you need to read license plates, use a higher resolution and lower frame rate (e.g., 4 MP at 10 fps) rather than a high frame rate.

Axis cameras also offer a feature called Zipstream, which dynamically reduces bitrate while preserving important details. If you enable Zipstream, you can often set the target bitrate lower than the calculator suggests – sometimes by 50% – because the camera adapts in real time.

Common Mistakes and Limitations

The most common mistake is mixing up units: bitrate is in megabits per second (Mbps), while storage is in gigabytes (GB). One byte is 8 bits, so a 4 Mbps stream uses 0.5 MB/s, or 43.2 GB per day. The calculator does this conversion for you, but when you read camera specs, be careful: some manufacturers list bitrate in kilobits per second (kbps), where 1 Mbps = 1000 kbps.

Another mistake is assuming the bitrate is constant. In practice, VBR streams fluctuate with scene complexity. The calculator gives an average, so your actual storage may vary by ±20%. Also, the formula is a rule of thumb – it works well for typical surveillance scenes but may overestimate for very static scenes or underestimate for extreme motion. For critical applications, use the camera’s own bitrate estimation tool or test with your actual scene.

The formula also assumes H.264 compression. H.265 (HEVC) is roughly 30–50% more efficient, so the calculator halves the quality factor for H.265. However, not all Axis cameras support H.265, and H.265 requires compatible clients and recording software.

Bitrate vs. Resolution vs. Frame Rate

It’s important to understand that resolution and frame rate are not independent of bitrate – they are the main drivers. Doubling the resolution roughly doubles the bitrate for the same quality. Doubling the frame rate also roughly doubles the bitrate, but the human eye perceives motion smoothly at 15–20 fps, so going from 15 to 30 fps may not be worth the extra storage.

For most Axis cameras, a good starting point is:

• 2 MP (1080p) at 15 fps: 2.1 Mbps (medium H.264)
• 4 MP at 15 fps: 4.2 Mbps
• 8 MP (4K) at 15 fps: 8.4 Mbps

These are for medium quality. If you need high quality, double the bitrate; for low quality, halve it. Remember that the camera’s sensor and lens quality also affect the perceived quality – a high bitrate cannot fix a poor lens.

Practical Uses of the Calculator

This calculator is useful in several scenarios:

• Network planning: Estimate the bandwidth needed for multiple cameras. For example, 10 cameras at 4.2 Mbps each require 42 Mbps of sustained bandwidth.
• Storage sizing: Calculate how many days of recording you can store on a given hard drive. A 4 TB drive (4000 GB) at 45.4 GB/day gives about 88 days of storage for one camera.
• Setting camera parameters: When configuring an Axis camera, you can enter the recommended bitrate as the target in the video stream settings.
• Comparing compression settings: See how much storage you save by switching from H.264 to H.265 or from high to medium quality.

Remember that the calculator provides an estimate, not a guarantee. Actual bitrates depend on the scene, lighting, and camera model. Always test with your specific setup before finalizing a large deployment.

Frequently Asked Questions

What is a good bitrate for a 4MP Axis camera?

For a 4MP Axis camera at 15 fps, a good H.264 bitrate is around 4 Mbps for medium quality. If you need higher detail, use 8 Mbps; if the scene is static, 3 Mbps may suffice. With H.265, you can halve those numbers.

Does the calculator work for all Axis cameras?

Yes, the formula is a general rule that applies to any IP camera, not just Axis. However, Axis cameras with Zipstream can achieve lower bitrates than the formula suggests, often 30–50% lower, because the camera dynamically adjusts compression.

How much storage do I need for 30 days of recording?

Multiply the daily storage from the calculator by the number of days. For example, a 4MP camera at 4.2 Mbps uses 45.4 GB/day, so 30 days is about 1.36 TB. For 10 cameras, you’d need about 13.6 TB.

What is the difference between CBR and VBR?

Constant bitrate (CBR) keeps the bitrate fixed, which makes storage predictable but wastes bandwidth on static scenes. Variable bitrate (VBR) adjusts the bitrate based on scene complexity, saving storage but making the bitrate fluctuate. Axis cameras support both; VBR is usually recommended for most applications.

Why is my actual bitrate higher than the calculator’s estimate?

If your scene has a lot of motion, noise, or fine detail (like foliage), the encoder may need more bitrate to maintain quality. Also, if you set the quality to high, the bitrate will be higher. Check your camera’s actual bitrate in the web interface and adjust accordingly.

Can I use the calculator for H.265?

Yes, the calculator includes H.265 options. H.265 is about 50% more efficient, so the quality factor is halved. For example, a 4MP camera at 15 fps with H.265 medium gives about 2.1 Mbps, which is half of the H.264 value.

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in mp | Resolution | MP | 4 | 0
in fps | Frame rate | fps | 15 | 1
in qual | Compression quality | H.264 Low=0.5, H.264 Medium=1, H.264 High=2, H.265 Medium=0.5, H.265 High=1 | 1
out bitrate | Recommended bitrate | Mbps | mp * fps * qual * 0.07 | 1
out storage | Daily storage | GB | (bitrate / 8) * 86400 / 1000 | 1