Collatz Conjecture Calculator

About this calculator

This calculator runs the Collatz conjecture sequence (also called the 3n+1 problem) on any starting number: if it's even, divide by 2; if it's odd, multiply by 3 and add 1. Repeat until you hit 1, and the calculator reports the number of steps and the highest value reached along the way.

It's a famous unsolved problem in mathematics — every number tested so far eventually reaches 1, but no one has proven it's true for all numbers. Math enthusiasts, students, and programmers use this calculator to explore the sequence and see how wildly the peak value can spike before collapsing back down.