How to Specify a TF Card Order
A TF card order is set by six things: the capacity, the speed class, the silicon grade and source, the controller solution, how the card is marked, and the packaging. Capacity is the one most often chosen wrongly, because nominal capacity is not recording duration — a 128GB card reports roughly 119GB to the host, and video bitrate decides how long that lasts. Speed class matters for continuous recording, because a card that writes more slowly than the camera records will drop frames rather than fail loudly. Get those six stated and the rest of the order follows.
Capacity — choose it from recording duration, not from the label
Work backwards from the workload. A dashcam recording at 1080p for two minutes needs a different card from one recording 4K continuously, and neither number is on the box. The practical method is to fill a known card, record until it stops, and measure what was captured.
| Nominal | Usable in the OS | Note |
|---|---|---|
| 32GB | Roughly 29.8 GB | Small but workable for occasional recording |
| 64GB | Roughly 59.6 GB | A common dashcam size |
| 128GB | Roughly 119 GB | The usual choice for continuous recording |
| 256GB | Roughly 238 GB | Where high-bitrate footage is kept on the card |
Speed class — what matters is sustained writes
Read speed is not the constraint for a camera; sustained write speed is. A card that writes below the bitrate of the recording device will stop keeping up silently, which shows up as dropped frames rather than an error. Match the speed class to the workload rather than buying the fastest card available.
- Continuous recording — verify sustained write speed on the actual device, not on a benchmark card
- Boot and data storage — read performance and stability matter more than write speed
- General data transfer — the class a general-purpose card carries is usually sufficient
Silicon grade and source — the line most quotes omit
Grade and source are not visible on a delivered card and cannot be inspected afterwards. They are established through what the supplier states in writing before production, and verified indirectly through a capacity test. A+ grade with named sources from SanDisk, Toshiba, Micron, SK Hynix, Intel or Samsung is what we quote against.
Package format, controller and marking
| Decision | Options | What it affects |
|---|---|---|
| Flash package | TSOP, BGA, LGA, COB, eMMC | Cost, availability and the mechanical footprint on your board |
| Controller solution | Alcor, ITE, Xinbang, Micov | Host compatibility, transfer behaviour and firmware update path |
| Marking | Screen print to order, unmarked, or retail pack | Identity and whether the card carries your logo |
| Packaging | Bulk, tray or retail | Your assembly process and your shelf presentation |
What to test before you commit
The check that matters is a full write-and-read-back across the whole card. H2testw on Windows and F3 on macOS and Linux both do this and both report the capacity you can actually use. Run it on a random sample from the batch you receive, not on a unit the supplier selected.
Send your requirement
We reply to business enquiries within 1 business day. If you are comparing suppliers, send the specification you were quoted — it makes the comparison meaningful.
Request a quoteFrequently asked questions
Which capacity should I specify for a dashcam?
It depends on resolution and bitrate rather than on any general rule. The reliable method is to record onto a known card, fill it, and measure the duration you actually get — then size the order with headroom for the formats you expect to ship.
Is A+ grade the same as industrial grade?
No. A+ describes the grade of the silicon. An industrial temperature rating and a published endurance figure are different claims, and a card that does not carry a published rating should not be described as industrial. Ask which claim the supplier is actually making.
Can you match a competitor’s capacity and grade?
Usually, if both are stated in writing. The specification is not the hard part — the hard part is confirming in writing that the second order matches the first, which is what we hold against a repeat order.
Do the cards come marked?
Card printing is done to order. Tell us your artwork and target body and we will confirm the method and whether it suits the surface you have chosen.