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About this tool
Measure your short-term working memory capacity with standard forward and reverse digit span tests.
The digit span test measures short-term working memory by showing a random string of digits one at a time and asking you to type them back — forward in the order shown, or reverse in the opposite order. This version starts at 3 digits, adds one digit after every correct recall and drops back one (never below 3) after two misses in a row, so your span settles at the longest string you can reliably hold. Results are graded against Miller's classic 7±2 range and charted attempt by attempt, with a CSV export of every trial.
Open Digit Span Test on AltFTool — it loads instantly in your browser.
Pick Digits Forward or Digits Reverse in the Test Mode card, then click the Start Test panel or press Space — the first sequence is 3 items.
Digits appear one at a time under 'Memorise This Sequence' (0.8 seconds each); when 'Your Turn — Recall the Sequence' shows, type them into the box and press Submit Answer or Enter.
Current Span, Best Span, Accuracy and Streak update after each trial and the span grade is read against Miller's 7±2; the CSV button in Attempt History downloads digit-span-test.csv.
The sequence grows by one digit after each success and shrinks after two consecutive misses, converging on your real ceiling instead of a preset length.
Reverse recall loads the same digits plus a mental reordering step, so the gap between your two spans is visible side by side.
Charts show accuracy at each sequence length and span across attempts, so a single unlucky trial does not define your score.
Most adults land between 5 and 9 digits forward, the range George Miller described as 7±2. This tool grades 5-6 as average, 7-8 as above average, 9 or more as exceptional, and 3-4 as the lower end of normal.
Reverse asks you to type the digits in the opposite order to how they appeared, which adds a manipulation step on top of storage. Most people score roughly one to two digits lower in reverse than forward, so compare reverse scores only against your own reverse scores.
One digit at a time: a 1-second pause after you start, then each digit held for 0.8 seconds before the next replaces it. The pacing is fixed, so a 7-digit sequence always takes about 5.6 seconds to present and every trial is timed the same way.
Capacity itself is fairly stable, but measured span usually rises with chunking — grouping digits into pairs, dates or phone-number shapes rather than storing nine separate items. Sleep, quiet and undivided attention also move scores; this is a self-test for curiosity and practice, not a clinical assessment, so see a qualified clinician if you are worried about memory changes.