What is a decillion?

A decillion is the number 1,000,000,000,000,000,000,000,000,000,000,000 — a one followed by thirty-three zeros. It equals one thousand nonillions and is the tenth power of a thousand after the initial thousand itself, which is where the prefix "dec-" (meaning ten) originates. Decillion-scale numbers are rare outside pure mathematics, cryptography, and theoretical physics, but they arise in combinatorial calculations, the size of certain hash spaces, and thought experiments about the universe's total information content.

Thirty-three zeros are impossible to count at a glance. Working with numbers this large requires automated tools to shift the decimal point reliably and produce the exact digit string every time.

Tool description

This tool converts numbers expressed in decillions to their full numeric form and vice versa. Enter a value in the "Decillions" field to see it expanded with all thirty-three zeros, or type an enormous number in the "Full Number" field to learn how many decillions it represents. The conversion is bidirectional and updates as you type.

Examples

Decillions Full Number
1 1000000000000000000000000000000000
3 3000000000000000000000000000000000
0.5 500000000000000000000000000000000
1.2 1200000000000000000000000000000000
0.001 1000000000000000000000000000000

Features

  • Instant bidirectional conversion between decillions and full numbers
  • String-based arithmetic handles 33+ digit numbers with perfect precision
  • Supports decimal input (e.g. 4.5 decillion → correct 34-digit output)
  • Runs entirely in the browser — no server processing needed
  • One-click swap to reverse the conversion direction

Use cases

  • Exploring cryptographic key-space sizes in security research
  • Converting extreme combinatorial results in theoretical mathematics
  • Writing out ultra-large values for academic papers and educational content

How it works

The converter uses string-based decimal shifting rather than JavaScript's native Number type. This avoids the 15–17 significant-digit limit of IEEE 754 floating-point arithmetic, ensuring that every zero is placed correctly even when working with 33-digit numbers.

  • Nonillion Number Converter — for numbers with 30 zeros
  • Million Number Converter — for numbers with 6 zeros