Unary & Tally Marks Converter — Numbers to Marks and Back
Convert a whole number to unary (a run of strokes) and to grouped tally marks (bundles of five), or count marks back into a number — live in your browser. See the count of complete groups and the remainder, choose your own mark, and copy the result.
How to Use
- Type a non-negative whole number to see it as unary strokes and as grouped tally marks.
- Or switch to “Count marks” and paste a run of strokes — they are counted back into a number.
- Change the mark character (default <code>|</code>) if you prefer a different stroke.
- Read off the number of complete five-bundles plus the remainder, and copy any result.
Unary, tally marks and base 1
Unary is the most basic way to write numbers: a value of n is simply n identical marks in a row. Five is |||||, eight is ||||||||. There is no zero symbol and no place value — the length of the string is the number. That makes unary effortless to understand but hopeless for big values: a thousand needs a thousand strokes, which is why this tool caps very long runs with a friendly note.
Tally marks are unary with one clever addition: marks are bundled into groups of five, and the fifth mark is drawn as a diagonal stroke across the previous four — the classic “gate”. Bundles of five are recognisable at a glance, so reading a tally becomes “five times the number of complete bundles, plus the leftover marks”. Twelve is two full bundles plus two singles (5 + 5 + 2); twenty-three is four bundles plus three.
Reading marks back into a number
Counting is just unary in reverse: total the marks. Switch the tool to “Count marks” and paste any run of strokes — spaces and line breaks are ignored — and you get the count back. ||||| returns 5; a tally sheet of three bundles and one extra returns 16. Because tally marks are unary at heart, the same routine handles both: every drawn stroke, diagonal included, counts as one.
Zero is the one special case. There is no mark for zero in either system, so a count of nothing is shown as an explicit “zero — no marks” note rather than an empty box, keeping the result unambiguous.
Quick reference
About the Unary & Tally Marks Converter — Numbers to Marks and Back
Unary & Tally Marks Converter — Numbers to Marks and Back is a quick, free tool for everyday tasks. It works in your browser and keeps everything on your device. Convert a whole number to unary (a run of strokes) and to grouped tally marks (bundles of five), or count marks back into a number — live in your browser. See the count of complete groups and the remainder, choose your own mark, and copy the result.
How it works
Type a value, then pick what you want to change it into. The answer appears straight away. It all happens on your own device, so it is fast and nothing you type is sent away. Just check that you picked the right “from” and “to” so you get the answer you wanted.
Want the deeper story? The Knowledge Base explains the ideas behind the tools in more detail.
Frequently Asked Questions
What is unary (base 1)?
Unary is the simplest numeral system: a number n is written as n identical marks. Three is “|||”, five is “|||||”. There is no zero digit and no place value — the length of the string *is* the number. Because the string grows one mark per unit, unary is wildly inefficient for large numbers, which is why this tool caps the run length.
How are tally marks different from unary?
Tally marks are unary with a grouping trick: every fifth mark is drawn as a diagonal stroke across the previous four, making bundles of five that are easy to count at a glance. So 12 is two full bundles (5 + 5) plus two single marks. It is the system used for live score-keeping, vote counting and head-counts.
Why group in fives?
Five is small enough to recognise instantly without re-counting, and the diagonal “gate” closing each bundle gives a clear visual full-stop. Counting then becomes “fives times the number of bundles, plus the leftovers”, e.g. 5×4 + 3 = 23, far faster than counting 23 separate strokes.
Can it convert marks back to a number?
Yes. Switch to “Count marks”, paste any run of strokes (spaces and line breaks are ignored), and the tool reports the total count. Five strokes “|||||” come back as 5.
Is anything uploaded?
No. The whole conversion runs in your browser with JavaScript — nothing is sent to a server.
How do I use the Unary & Tally Marks Converter — Numbers to Marks and Back?
Just type or paste your value. The answer shows up right away — there is no button to press. Change anything and it updates by itself.
Does it cost anything or need an account?
No. The tool is completely free, there is no account to create, and it keeps working offline after the page first loads.
Is anything I type uploaded?
No. The tool works entirely on your device, so the values you enter never leave your browser.
Common Use Cases
Teaching counting
Show pupils how tally bundles of five make a number quick to read, with the groups-plus-remainder spelled out.
Score & vote tallies
Turn a running total into clean tally marks for a scoreboard, poll or head-count sheet, or read a tally sheet back into a figure.
Understanding base 1
See concretely why unary length equals the value, and why every other number system uses place value instead.
Puzzles & ciphers
Encode small numbers as strokes for treasure-hunt clues, escape rooms or stylised counters.
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