Skip to calculator
Birthday Formula
instacalc
Birthday Formula
Calc
Text
Graph
Present
Remix
Search
Ctrl K
Calc
Text
Graph
Present
Birthday Formula
Remix
Birthday Formula
R1
people = 23
+
R2
days = 365
+
R3
pairs = (people * (people -1)) / 2
+
R4
chance per pair = pairs / days
+
R5
$e^(-chance per pair) * 100
R6
$(100 - chance different)
+
row
enter
Insert
instacalc.com/3372
Made with
instacalc
The calculator that shows your work.
Remix "Birthday Formula" into your own editable copy. Tweak it, share it, make it yours.
Remix this calc →
Explore 1,000+ examples
Calcs
Explore
Keypad
Search
More