How the calculation works
TB = GB ÷ 1,000 (decimal, as labels count); GiB = GB × 1,000,000,000 ÷ 1,073,741,824 (binary, as Windows shows)
A worked example
512 GB is 0.512 TB: divide by 1,000. Windows shows the same 512 GB as 476.84 GiB, because it counts 1,073,741,824 bytes to its "GB"; a 1 TB card shows as 931.32 GiB.
Decimal and binary units
Memory cards, USB sticks and drives are sold in decimal units: 1 GB is 1,000,000,000 bytes and 1 TB is 1,000 GB. Windows counts in binary units of 1,073,741,824 bytes (a gibibyte, GiB) but labels them GB, so every card looks about 7 % smaller there, and every terabyte about 9 % smaller.
RAM is the exception
RAM capacities are binary by convention: a 16 GB module holds 16 GiB. Prices per GB compare RAM with RAM only, so the difference never mixes into a ranking.
Common questions
How many GB are in a TB?
1,000 on every label. Windows shows a 1 TB card as about 931 GB because it counts in binary units.
Is my card fake if it shows less than the label?
Not for that reason: about 7 % less in Windows is normal. A card that reports far more than it can store is another matter; test a new card's full capacity with a verification tool before you trust it with photos.
Method: arithmetic from the label values you enter. Reviewed .