NAND Size - GamerTunerit/Guide GitHub Wiki
A valid NAND backup should be one of the following sizes in most situations.
Occasionally, you will get a backup with a different size than one of these listed. It is fine for a backup to be larger than expected, just ensure that it is never smaller than the sizes listed.
Your backup should match one of the sizes on this page; if it does not, you should delete it and make a new one!
The brand name refers to the manufacturer of the NAND chip in your device, not your SD card.
https://github.com/Plailect/Guide/wiki/FAQ#faq_rednand
2DS:
+ Toshiba NAND:
988.807.168 bytes = 943 MB
+ Toshiba NAND:
1.979.711.488 bytes = 1.84GB
+ Samsung NAND:
1.000.341.504 bytes = 954 MB
+ Samsung NAND:
1.300.234.240 bytes = 1.21GB
Old 3DS:
+ Toshiba NAND:
988.807.168 bytes = 943 MB
+ Samsung NAND:
1.000.341.504 bytes = 954 MB
New 3DS:
+ Toshiba NAND:
1.979.711.488 bytes = 1.84GB
+ Samsung NAND:
1.300.234.240 bytes = 1.21GB