🔔 Video Doorbell Storage Calculator
Enter your typical daily motion-triggered events, clip length, and how long you want to keep recordings, to see the storage you'll need.
The event arithmetic
A doorbell records only when triggered, so the total is seconds of footage rather than days of it:
seconds = events per day × clip length × retention days
GB = seconds × bitrate(Mbps) / 8 / 1000
20 × 30 × 30 = 18,000 s
18,000 × 2 / 8 / 1000 = 4.50 GBTwenty half-minute clips is ten minutes a day, 0.7% of it. That same 2 Mbps stream running continuously for thirty days would take 648 GB, so event recording saves a factor of 144. Scaling the event count at the default clip and bitrate:
| Events per day | Per day | 30 days |
|---|---|---|
| 10, quiet close | 0.08 GB | 2.3 GB |
| 20, default | 0.15 GB | 4.5 GB |
| 50, front street | 0.38 GB | 11.3 GB |
| 100, busy pavement | 0.75 GB | 22.5 GB |
Where the estimate drifts
- Pre-roll is not counted. Doorbells that buffer 3-6 seconds before the trigger add that to every clip, which is a fifth more than the 30 s you entered.
- Event counts are seasonal. Longer daylight or a hedge in leaf multiplies triggers. Log a week from the app before buying a card.
- 2 Mbps suits 1080p. A 2K doorbell wants about 4 Mbps and a head-to-toe 1:1 sensor more again, roughly doubling every figure above.
Frequently asked questions
How much storage does a video doorbell use per month?
About 4.5 GB for 20 events a day of 30 seconds at 1080p. A busy front door at 100 events a day uses 22.5 GB over the same month.
Is a 32GB microSD card enough for a doorbell?
Comfortably at typical use: 29 GB usable at 0.15 GB a day is roughly six months. At 100 events a day it falls to about 39 days, after which the card overwrites its oldest clips.
Why does a doorbell need so much less space than a security camera?
Duty cycle. A doorbell captures well under 1% of the day while an NVR camera records all of it, and the same bitrate over 1% of the time costs 1% of the storage.