1. Loop Recording: The Concept That Fixes Everything
A dash cam never stops recording and never fills up: it records in short segments (1-3 minute files) and, when the card is full, overwrites the oldest file. This is why 'how long can it record' has a strange answer — indefinitely forward, but only backward as far as your card allows. The system works because of one safeguard: the G-sensor locks the file on impact, and locked files are never overwritten. Your job is just to make sure the card is big enough that ordinary (unlocked) driving history lasts long enough to matter.
- Segments of 1-3 minutes, oldest overwritten
- G-sensor locks collision files permanently
- Card size = how many days of history you keep
2. How Much Footage Fits: The Real Numbers
Bit rates vary by model, but honest planning numbers: a single-channel 4K camera writes roughly 20-25GB per 3 hours of driving; 1080P about a third of that; and multi-channel cameras multiply by channel count — a 3-channel 4K unit (like the G12 class) consumes roughly 3x. Practical translations for a 1-hour-daily commuter: 64GB ≈ 3-4 days of history, 128GB ≈ a week, 256GB ≈ two weeks. Rideshare and delivery drivers should double those cards — their hours are longer and their dispute window is longer.
- 4K single: ~20-25GB / 3 hrs
- 3-channel 4K: ~3x that
- 64GB ≈ 3-4 commuter days, 128GB ≈ a week
3. The Card That Matters: High-Endurance Only
The #1 'my dash cam corrupted' cause is not the camera — it is a consumer SD card. Dash cams write continuously, thousands of hours a year; consumer cards are rated for occasional photo bursts. High-endurance cards (sold for surveillance) handle the write duty cycle and cost a few dollars more. Buy the right class: 64-128GB high-endurance for singles, 128-256GB for multi-channel units. Format the card in the camera monthly — a ten-second habit that prevents most corruption complaints.
- Continuous-write rating, not photo class
- 64-128GB singles, 128-256GB multi-channel
- Format in-camera monthly
4. Settings That Protect the Important Clips
Three settings decide whether your needed clip survives: G-sensor sensitivity at medium (too high locks everything — the card fills with locked junk videos of potholes; too low misses real impacts), resolution matched to purpose (4K for plate reading at night; 1080P per channel if storage is tight), and parking-mode bit rate if hardwired (some models drop to a lower rate while parked to stretch the card). Check the lock-file folder monthly and clean genuine junk.
5. Buyer and Retailer Notes
Shoppers: a camera that does not include or explicitly support high-endurance cards is a red flag at any price. Retailers: bundle the card — a 128GB high-endurance card alongside the unit raises order value and kills the top warranty complaint before it happens (we ship card-ready units and can supply cards with the wholesale order; ask on WhatsApp). Fleet operators: standardize 256GB across vehicles so dispute windows are uniform.