Bitrate to Storage Calculator
A single stream at 1 Mbps writes 450 MB per hour, which is 10.8 GB per day. Multiply by the camera count and divide the usable drive capacity by the result to get retention in days.
Values update as you change the inputs. Where a figure cannot be computed honestly from what manufacturers publish, this calculator says so rather than showing a zero.
Gear that matches this answer
This grid re-orders itself against the number you just calculated, smallest adequate option first.
Seagate Skyhawk 4TB Video Internal Hard Drive
$159.99Rated for continuous write from multiple camera streams, which is the entire difference between a surveillance drive and the cheaper desktop drive beside it.
- Capacity
- 4 TB
Prices change often.
Western Digital 4TB WD Purple Surveillance Internal Hard Drive, 256 MB Cache
$189.99The direct WD equivalent of the Skyhawk, with a larger cache that helps when many streams are writing at once.
- Capacity
- 4 TB
Prices change often.
Seagate Skyhawk 8TB Video Internal Hard Drive
$309.99Doubling the drive doubles the retention, and retention is the specification people regret after the one event they needed it for.
- Capacity
- 8 TB
Prices change often.
Western Digital 8TB WD Purple Surveillance Internal Hard Drive, 256 MB Cache
$354.99Eight terabytes of surveillance rated storage, the usual pairing with a sixteen channel recorder.
- Capacity
- 8 TB
Prices change often.
Seagate Skyhawk AI 8TB Video Internal Hard Drive
$329.99Built for recorders running analytics on many streams at once, where the drive is being read for detection while it is still writing.
- Capacity
- 8 TB
Prices change often.
Western Digital 8TB WD Purple Pro Surveillance Internal Hard Drive
$399.99The higher workload rating in the WD surveillance line, intended for the largest camera counts.
- Capacity
- 8 TB
Prices change often.
The formula
MB per hour = bitrate Mbps x 450, and days = usable drive MB / (cameras x MB per hour x hours per day)
This calculator takes the bitrate you measured on your own recorder rather than a typical figure, so it is the accurate one if you already have a system running.
Common questions
How much storage does 1 Mbps of video use per hour?
A single video stream at 1 Mbps writes 450 MB every hour, which works out to 10.8 GB per day for one continuous camera. Multiply that 450 MB per hour figure by bitrate, camera count and recording hours per day to get total daily storage, then divide the drive usable capacity by that daily figure to get retention in days.
How do I calculate storage from a bitrate I measured myself?
Multiply the measured bitrate in Mbps by 450 to get megabytes written per hour, then multiply that by camera count and hours recorded per day to get daily storage. Divide the drive usable capacity by that daily figure to get days of retention. A bitrate read directly off a recorder is more accurate than a typical resolution based figure.
Why use a measured bitrate instead of a typical one by resolution?
A typical bitrate by resolution is a convention, useful for planning a system not yet bought. Once a recorder is running, its actual reported bitrate reflects real scene motion, lighting and encoder settings, which can run higher at night or in windy scenes, so it produces a more accurate retention estimate than a generic resolution based figure ever could.
How much data does one camera use per month at 6 Mbps?
At 6 Mbps recording continuously, one camera writes 450 times 6, or 2,700 MB per hour, roughly 64.8 GB per day, and about 1,944 GB, close to 1.9 TB, over a 30 day span. Recording fewer hours per day, such as motion only capture, cuts that monthly total roughly in proportion to the hours actually recorded.
Does recording fewer hours per day change how long a drive lasts?
Yes, directly. Retention is inversely proportional to hours recorded per day, so a camera set to record 12 hours a day instead of 24 roughly doubles the number of days a given drive holds. Motion only recording can push hours per day even lower, which is why motion triggered systems often store months of footage on modest drives.
Get the system planning sheet
The camera count, storage and PoE budget worksheet, plus the wiring checklist, as one printable page.
Keep going
A calculated figure is a planning number, not a promise. Every answer here comes from published standards and manufacturer specifications, and real installations vary with light, weather, scene motion and how a camera is actually aimed. Where a figure cannot be computed honestly from what manufacturers publish, this calculator says so rather than showing a zero.
Before you point a camera at anything. Aim at your own property and your own boundary, never into a neighbour's windows. Cameras in bedrooms, bathrooms or anywhere with a reasonable expectation of privacy are a serious legal problem, including for guests and anyone who works in your home. Audio is legally different from video, many US states require the consent of every party to a recorded conversation, and several recorders capture audio by default, so check your own state before enabling it. This is researched general information and not legal advice.