Short-term memory capacity is approximately?

• A. About 3 items for 5-10 seconds
• B. About 12 items for a few minutes
• C. About 20 items for hours
• D. About 7±2 items for around 20-30 seconds

Answer: (D)

Short-term memory has a limited capacity and a brief duration. The classic finding is that you can hold about seven items, give or take two, in short-term memory. These items are chunks, so how much you can memorize depends on how you group information into meaningful units. For example, digits or letters can be chunked into larger units like dates or familiar sequences, which can effectively increase the number of items you can recall.

Without active rehearsal, those items last only around 20 to 30 seconds before they fade. Rehearsal helps keep them active longer or moves them into long-term memory.

So the best answer reflects roughly seven plus or minus two items for about 20–30 seconds.