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About this tool
Measure your short-term memory span with digit, letter, and visual sequence tests. Track your span over time and learn the neuroscience behind it.
The Memory Span Calculator measures your short-term memory span with an adaptive sequence test: it shows a sequence one item at a time, asks you to type it back, then lengthens the sequence by one item after a correct answer and shortens it after repeated errors. Four modes are available — digits forward, digits reverse, random letters and coloured squares — and your span is reported against Miller's classic 7±2 range. Students, cognitive-psychology learners and anyone curious about their working memory get a running span chart, per-length accuracy and a CSV export of every attempt.
Open Memory Span Calculator on AltFTool — it loads instantly in your browser.
Pick one of the four Test Mode cards — Digits Forward, Digits Reverse, Letters or Visual Colours — then click Start Test to watch the sequence, one item every 800 ms.
When the panel switches to "Your Turn — Recall the Sequence", type the items separated by commas or spaces and press Submit Answer; a correct recall adds one item to the next sequence and repeated misses take one away.
Read the Current Span, Best Span, Accuracy and Streak cards with the Span Over Time and Accuracy by Length charts, then use the CSV button in Attempt History to download memory-span-test.csv.
The sequence grows by one item after every correct recall and steps back down after repeated misses, so it converges on your actual ceiling instead of a preset length.
Digits reverse scores your answer against the reversed sequence, isolating the manipulation load that plain forward recall does not test.
Span-per-attempt and accuracy-by-length charts plus a CSV export let you see the length at which you start failing, not just a single headline number.
Most adults land between 5 and 9 items, the range George Miller described as 7 plus or minus 2. This tool grades 5-6 as average, 7-8 as above average and 9 or more as exceptional; anything under 5 is at the low end of the normal distribution rather than automatically a problem.
Each item appears for 800 milliseconds, after a 1-second pause before the sequence starts. That pacing is deliberate — it is fast enough to discourage writing items down or rehearsing them aloud item by item.
Reverse span is normally about one item shorter, because you must hold the sequence and mentally reverse it at the same time. Forward span mostly measures storage; backward span adds manipulation, which is why clinicians treat the two as separate measures.
No. It is an informal, self-administered version of a digit-span task for curiosity and practice, with no normed scoring, no supervision and no control over distractions. Persistent memory difficulties that affect daily life should be discussed with a doctor rather than diagnosed from a browser test.
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