I often have to generate Fibonacci numbers so I created this simple online utility that does it for me. It lets you generate however many Fibonacci numbers you need starting from any position or value. It works in the browser and is powered by alien technology from the future.

Fibonacci Number Generator Options

Starting Position or Value
Count and Separator

Fibonacci Number Generator Examples (click to try!)

Fibonacci Numbers from a Specific Position
In this example, we generate Fibonacci numbers from the specified position. To do it, we've selected "Start from a Position" option and entered 10 as the starting position. This option starts generating Fibonacci numbers from the 10th member of the sequence. The 10th Fibonacci number F10 is 55, so we start with it and calculate the next 20 values.
Start from a Position
Find Fibonacci numbers starting from this position.
How many values to generate?
Separate Fibonacci numbers with this value.
Decimal Base
Fibonacci Numbers from a Specific Value
In this example, we calculate Fibonacci numbers from the specified value. To do it, we've selected "Start from a Value" option and entered 20. However, 20 is not a Fibo number, so we seek the next largest Fibo, which happens to be 21. Then we compute the next 50 Fibonacci numbers and separate them with a comma.
21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811, 514229, 832040, 1346269, 2178309, 3524578, 5702887, 9227465, 14930352, 24157817, 39088169, 63245986, 102334155, 165580141, 267914296, 433494437, 701408733, 1134903170, 1836311903, 2971215073, 4807526976, 7778742049, 12586269025, 20365011074, 32951280099, 53316291173, 86267571272, 139583862445, 225851433717, 365435296162
Start from a Value
Find Fibonacci numbers bigger or equal to this value.
How many values to generate?
Separate Fibonacci numbers with this value.
Decimal Base
Large Octal Fibonacci Numbers
This example computes ten Fibonacci numbers in the octal base starting from the F200 position. As the Fibonacci series grows exponentially fast (asymptotic to 5-0.5×φn), the 200th Fibonacci series member in base-8 is 46 digits long.
Start from a Position
Find Fibonacci numbers starting from this position.
How many values to generate?
Separate Fibonacci numbers with this value.
Octal Base

How Does This Fibonacci Number Generator Work?

This Fibonacci number generator works entirely in your browser and is written in JavaScript. It uses only one external library called bignumber.js, which lets it calculate Fibonacci numbers with arbitrary precision. It starts by defining two initial values var first = 0 and var second = 1, and creating an array that will hold all computed Fibonacci numbers. Depending on the start and count values (starting value or position and Fibonacci sequence length; specified in options) it adds the initial values to the array. Then, it starts a simple for loop that runs as long as array.length (number of currently calculated Fibonacci numbers) is less than count (number of values to compute; specified in options). In every loop iteration, it calculates the current Fibonacci number as a sum of first + second members, then it checks if start (starting value or position; specified in options) is equal or greater than current and if it is, it calls the push(current) function to add the current value to the array. After this, it redefines first and second variables as follows: first = second, second = current, and repeats the loop. Finally, when the loop ends, it converts all the numbers in array to the base (Fibonacci number base; specified in options) by calling toString(base) function, and then formats all numbers by using a join(separator) function and prints them to the screen.

Created by Browserling

This fibonacci number generator was created by me and my team at Browserling. Behind the scenes, it's actually powered by Browserling's programmer tools that are used by millions of people every month. Browserling itself is an online cross-browser testing service powered by alien technology. Check it out!

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