microSD cards for retro handhelds: sizes, classes and slots

A microSD card is the removable card that fits a retro handheld's slot. Makers state a slot and often a maximum size, from 256GB to 2TB in this catalogue, and the SD Association defines the capacity and speed labels printed on cards. This guide covers both, and names no brands or shops.

What does the card do in a handheld?

It depends on the device, and the maker pages differ. Several Anbernic devices, such as the RG35XX SP, list a 64GB TF card (Anbernic's term for microSD) as included storage, with dual card slots. The Powkiddy RGB30 page assigns jobs to its two slots: "TF1 for the OS, TF2 for games". By contrast, the Retroid Pocket 5 lists 128GB of built-in UFS 3.1 storage plus a TF card slot, so the card there adds space on top of the internal storage.

So read the page for what the card is used for. Where a maker assigns the operating system to a card, as Powkiddy does with TF1, that card matters more than one that only adds space. See Android vs Linux retro handhelds for how the two families differ.

What do makers state about slots and maximum sizes?

The Miyoo Mini Plus page says storage is expandable via microSD and offers a 64GB card or none. The Miyoo A30 page lists 64GB in each colour option and states no expansion slot, and the ModRetro Chromatic and Trimui Smart Pro files state none either. Of the 34 retro handhelds, 18 state a maximum card size, 13 state a slot with no maximum and three state no slot. A missing maximum is not a limit of zero. It means the maker has not told us, so ask before buying a large card.

How much card space can each device take?

The stated maximums fall into the SD Association's capacity classes, which makes the table below a quick filter. The class column is our reading of the Association's ranges, not a maker claim.

Some simple arithmetic shows what that means. The RG35XX SP lists dual slots at up to 512GB each, so two cards could add up to 1,024GB (1TB) of card space. The Powkiddy RGB30 lists 16GB to 256GB per slot across two slots, so up to 512GB across both, and its page lists the 16GB variant with no expansion card. The RG405M lists 128GB eMMC plus a card of up to 2TB, so the card can be many times the built-in storage. The Retroid Pocket 5 lists 128GB of UFS 3.1 plus a card slot but no maximum, so there is no stated ceiling to calculate with.

Who this helps: if you want one large card, the Anbernic RG405M, RG556 and RG DS and the Mangmi Air X are the only pages that state a 2TB maximum, and the Trimui Brick and Smart Pro S state 1TB. If you prefer a modest card, the stated 256GB to 512GB limits cover it with room to spare. If your device states no maximum, treat any large card as an unconfirmed purchase.

What do the capacity labels mean?

The SD Association defines four capacity standards, and microSD cards use the same names (SD capacity standards). According to its page:

• SD: up to 2GB, FAT12 or FAT16.
• SDHC: over 2GB up to 32GB, FAT32.
• SDXC: over 32GB up to 2TB, exFAT.
• SDUC: over 2TB up to 128TB, exFAT.

Two things follow. First, every maximum in the table above, from 256GB to 2TB, falls inside the SDXC range, and 2TB is the top of it. Powkiddy's 16GB lower bound is an SDHC size. The SD Association says an SDHC card works in SDHC, SDXC and SDUC hosts, but that an SDXC host can use SD, SDHC and SDXC cards only. Second, the SD Association says an SDUC card must only be used with SDUC host devices (SD card capacity choices). No maker in our catalogue states SDUC support, so a card above 2TB is outside every stated limit.

The Mangmi page is worth a second look. It lists microSD up to 2TB and names FAT32, while the standard's file system for SDXC is exFAT. The maker's page does not explain how these fit together, so check its guidance on formatting before you buy a large card.

What do the speed labels mean?

Cards carry several overlapping symbols, all described on the SD Association's speed class page (SD speed classes).

• Speed Class (C2, C4, C6, C10): the page says symbols with a number indicate minimum writing speed, and links Class 10 to 10MB/s.
• UHS Speed Class (U1, U3): also a minimum write speed. U1 is shown at the same 10MB/s level as Class 10.
• Video Speed Class (V6 to V90): also a minimum write speed, which the page frames around video recording.
• Application Performance Class (A1, A2): a separate class for application performance, described as based on measurement under given conditions (Application Performance Class). The page says A2 performance is available only with an A2 host and an A2 card; at least A1 performance is available with a mixed pair.

The speed class page also says the classes apply to any write or read application that needs an assured minimum constant sequential access performance. It advises choosing a card whose class symbol is the same as or higher than the host's, and warns that the expected speed is not guaranteed when the host and card use different symbol types, for example a Class 10 host with a U1 card.

No maker page in the catalogue states which speed class or bus it supports. That means we cannot say whether a given handheld benefits from a faster symbol. The sensible reading is that a label such as A1 or U1 describes the card, and whether the device uses it is something to ask the maker.

What should you check before buying a card?

1. Confirm the device has a card slot at all, as the SD Association's own consumer advice asks (choosing a microSD card).
2. Compare the card's capacity with the maker's stated maximum, and note whether the maker gives a format such as FAT32.
3. Read the symbols on the card against the speed class page above.
4. Plan for two cards if you have dual slots, and note which slot the maker assigns to the system. Keep a note of what is on each card before you swap or reformat anything.

Our research method never covers game files. For the rest of your shortlist, see how to choose a retro handheld or best retro handhelds.