Collatz Sequence Calculator (3n+1)
Math ToolsSteps and peak value for the 3n+1 problem
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All history →Collatz Sequence Calculator (3n+1) — at a glance
Follow a number as it falls to 1 under the Collatz rule.
27
Generate Sequence
111 steps
Peak 9232
How to use it — step by step
A positive whole number to start from.
1
Add your text
Paste or type your input into the box. The Sample button fills in an example.
2
Press Generate Sequence
The result is made instantly inside your browser.
3
Copy the result
Use the Copy button, or send it to another tool.
Pro tips
Small things that make the result better.
✦If even, divide by 2. If odd, multiply by 3 and add 1.
✦27 takes 111 steps and rises to 9,232.
✦Nobody has proved it always ends at 1.
Quick facts
Freeno signup
Privateruns in your browser
Instantresult in a second
No limituse it as often as you like
Frequently Asked Questions
What is the Collatz conjecture?+
It says every positive start number eventually reaches 1. It is unproven.
Is there a limit?+
Starting numbers up to a trillion are accepted.
Is my data safe?+
Yes. Everything runs inside your own browser. Your text, files and images are never uploaded to any server.
Is this tool really free?+
Yes — completely free, no signup, no watermark and no usage limit.
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