Video calculator
H.265 Bitrate Calculator
Video bitrate, audio bitrate, duration, file size, and bits per pixel per frame.
HEVC file size and target bitrate
Estimate storage from average bitrate, or calculate the video bitrate needed for a target file size.
- Estimated size
- 1.81 GiB
- Total bitrate
- 4.13 Mbps
- bpppf
- 0.0643
- Target video bitrate
- 4.42 Mbps
Bitrate estimates are sizing math, not a quality guarantee. Content and encoder settings matter.
Formula notes
File size is average total bitrate multiplied by duration: size MB = Mbps * seconds / 8. The target
bitrate path reverses that formula and subtracts audio bitrate.
What this calculator is for
Use this H.265 bitrate calculator to plan storage, transfer bandwidth, or target video bitrate before an encode. It is useful for HEVC camera recordings, screen captures, OBS tests, security-camera storage estimates, and archive batches where the final file size matters.
The calculator separates deterministic sizing math from subjective quality. The estimated file size comes directly from bitrate and duration. Whether that bitrate looks good depends on the encoder and the source footage.
Key parameters
- Resolution and frame rate: used to report bits per pixel per frame, a quick density check.
- Duration: the length of the final clip or recording window.
- Video bitrate: the average HEVC video data rate in Mbps.
- Audio bitrate: added to the video bitrate for total file-size planning.
- Target file size: used to reverse the formula and find an allowed video bitrate.
H.264 to H.265 bitrate planning
H.265 can often deliver similar quality at a lower bitrate than H.264 because HEVC uses larger coding tree units, better prediction, and more efficient motion compensation. A common first planning estimate is to try H.265 at roughly 50-60% of the H.264 bitrate, then test a representative clip. The saving is usually larger for 4K camera footage than for simple low-resolution screen captures.
Quality caveat
H.265 can deliver similar visual quality at lower bitrate than H.264, but the right number depends on motion, noise, grain, encoder preset, bit depth, and whether the encode is constant quality or average bitrate.
Streaming, recording, and archive use
For live streaming, start from the platform's upload and codec limits and leave headroom for network variation. For local recording, VBR usually gives better quality-per-bit than strict CBR. For long-term archival, a constant quality mode is often better than forcing an exact bitrate unless storage quotas are fixed.
When to lower resolution instead of bitrate
If the target bitrate is too low, lowering resolution or frame rate can look better than keeping the full image and starving the encoder. Fast motion, noise, and film grain need more bits per pixel. A clean talking-head video can survive a lower bitrate, while sports, gameplay, surveillance at night, and handheld footage usually need more bitrate or a smaller frame size. This is why a short test encode is more reliable than a universal bitrate table.
Worked file-size example
A one-hour video at 4 Mbps video plus 128 kbps audio has a total bitrate of
4.128 Mbps. Multiply by 3600 seconds and divide by 8 to get about
1858 MB, or roughly 1.8 GiB before small container overhead.
Before using the target bitrate
- Add every audio stream that will ship in the final file.
- Leave space for container metadata, subtitles, and muxing overhead when the size budget is strict.
- Test a representative clip before applying one bitrate to a full batch.
Frequently asked questions
How do I calculate H.265 video file size from bitrate?
Add the video bitrate and audio bitrate, multiply by duration in seconds, then divide by 8 to convert megabits to megabytes. The calculator reports the estimated size in GiB and also reverses the formula when you enter a target file size.
Is H.265 always half the bitrate of H.264?
No. H.265 often reaches similar visual quality at 40-50% lower bitrate than H.264, especially at higher resolutions, but the exact savings depend on motion, grain, encoder preset, rate control, bit depth, and hardware encoder quality.
What bitrate should I use for OBS streaming with H.265?
Use the platform recommendation first, then test against upload bandwidth and dropped frames. For private HEVC streams, start around 6-10 Mbps for 1080p60, 12-18 Mbps for 1440p60, and 24-35 Mbps for 4K60, then adjust for motion and audience bandwidth.
Should I use CBR, VBR, or CRF for H.265?
Use CBR when a live stream or network path needs predictable bandwidth. Use VBR for local recording when you still need a size target. Use CRF or constant quality for archival encodes when consistent quality matters more than an exact file size.
Why does the calculated bitrate not guarantee video quality?
Bitrate is only the data budget. Visual quality also depends on source complexity, encoder implementation, preset speed, lookahead, B-frames, noise, grain, color depth, and whether the content is screen capture, camera video, animation, or fast action.