Calculate video or audio recording time from storage size and bitrate, with typical camera bitrates built in, or find the storage or bitrate you need.

Typical average bitrates. Your camera or recorder settings may differ; pick Custom to enter yours.

Capacity and daily schedule
Allow for reserved space, other files and recording overhead here.

Calendar-day duration uses this daily recording schedule.

Recording Time Formula

The recording time calculator estimates active recording hours, nominal storage required, or the maximum average bitrate per stream. It supports decimal MB/GB/TB and binary MiB/GiB/TiB capacity, equal-rate simultaneous streams, a usable-capacity allowance and daily recording schedules. Use the actual combined audio/video bitrate for each stream; no additional codec ratio is applied.

RT = (SC × U × 8000) / (BR × N × 3600)

For this displayed formula only, SC is nominal decimal GB, U is the usable fraction (percentage divided by 100), BR is average Mbps per stream and N is the stream count. The widget converts other selected units before using the equivalent bytes-and-bits equation. RT is active recording hours.

BRₜₒₜₐₗ = BR × N
Variable Description Unit
RT Total recording time available hours
SC Storage capacity of the card, drive, or media GB
BR Average combined audio/video bitrate per stream Mbps
N; U Equal-rate stream count; usable nominal-capacity fraction dimensionless

Enter the actual encoded average bitrate once. Compression affects that bitrate; applying a second codec multiplier would count it twice. For unequal-rate streams, use their arithmetic mean with the stream count, or their summed bitrate as one stream.

Rearranged Forms

Choose a solve mode to find recording time, nominal storage required, or maximum average bitrate per stream. The corresponding GB/Mbps/hour rearrangements are:

SC = (RT × BR × N × 3600) / (8000 × U)
BR = (SC × U × 8000) / (RT × N × 3600)
CalendarDays = (RT) / (ActiveHoursPerDay)

How to Use the Calculator

  1. Choose the value to solve for, then enter the shown required inputs and their units.
  2. Use the average combined bitrate per stream and the number of equal-rate streams; presets are illustrative examples.
  3. Set usable capacity and active recording hours per day under Capacity and daily schedule when needed.
  4. For a calendar-day duration, the entered hours per day determine the active recording time.
  5. Calculate and review both active recording time and estimated calendar retention.

This is useful for SD cards, SSDs, DVR and NVR storage planning, podcast capture, body cameras, dash cams, field recorders, and long-form surveillance systems.

Quick Planning Shortcut

For one hour of recording, the required storage can be simplified into a compact planning formula.

SC₁ₕᵣ = 0.45 × BR × N / U

Each 1 Mbps of recorded total bitrate produces 0.45 decimal GB per active hour. For nominal capacity planning, multiply by active hours and divide by usable fraction. The table assumes one stream and 100% usable capacity.

Bitrate Streams Storage per Hour
1 Mbps 1.0 0.45 GB/hour
5 Mbps 1.0 2.25 GB/hour
8 Mbps 1.0 3.60 GB/hour
10 Mbps 1.0 4.50 GB/hour
25 Mbps 1.0 11.25 GB/hour
50 Mbps 1.0 22.50 GB/hour
100 Mbps 1.0 45.00 GB/hour

Example Calculations

If a recorder has 256 GB of storage and captures at 8 Mbps with one stream and 100% usable capacity, the expected recording time is:

RT = (256 × 8000) / (8 × 1 × 3600) ≈ 71.11 hours

If you need 6 hours of recording at 25 Mbps with one stream and 100% usable capacity, the storage required is:

SC = (6 × 25 × 1 × 3600) / (8000) = 67.5 GB

Important Notes

  • Use the correct bitrate. Audio-only devices are often specified in kbps, not Mbps. Convert by dividing by 1000 before entering the value. For example, 128 kbps becomes 0.128 Mbps.
  • Handle multiple streams once. Enter the average bitrate per equal-rate stream and the stream count, or use the combined bitrate as one stream. Include all recorded audio and video tracks.
  • Variable bitrate changes storage use. For VBR media, use the average bitrate for a typical estimate or a higher planning value for extra safety.
  • Leave free space. Real systems may reserve some capacity for formatting, metadata, indexing, file system overhead, or loop-recording behavior.
  • GB and GiB use different units. One GB is 1,000,000,000 bytes; one GiB is 1,073,741,824 bytes. The same physical capacity has different numeric values in these units; a correct conversion preserves recording time.
  • Higher quality means shorter duration. Increasing resolution, frame rate, bit depth, or audio quality usually increases bitrate and reduces the total hours you can store.

Why Recording Time Changes

Recording duration is controlled by a simple tradeoff: more storage increases time, while more data per second decreases time. Small changes in bitrate can have a large effect on long recordings, which is why bitrate planning is important for event coverage, security retention targets, livestream backup, and portable media capture.

Use this calculator when you need a fast estimate for how long a card or drive will last, how large a drive should be for a target retention period, or what bitrate ceiling fits within a fixed storage budget.