The direct answer
A quintillion has 18 zeros: 1,000,000,000,000,000,000 = 1018.
A quintillion is 1,000 quadrillion. It has six groups of three zeros after the leading 1, which makes the zero count easier to check.
See the zeros in groups of three
Start with the 1 and count the zero groups to its right. Each complete group contributes three zeros, so 6 groups × 3 zeros = 18 zeros.
Previous and next named numbers
| Position | Name | Written number | Power |
|---|---|---|---|
| Previous | quadrillion | 1,000,000,000,000,000 | 1015 |
| Current | quintillion | 1,000,000,000,000,000,000 | 1018 |
| Next | sextillion | 1,000,000,000,000,000,000,000 | 1021 |
Each move to the right multiplies the number by 1,000 and adds three zeros.
How to say and write quintillion
The number 1,000,000,000,000,000,000 is written in words as one quintillion. A number such as 2,000,000,000,000,000,000 is two quintillion; the scale word itself does not become plural inside a number name.
Short-scale note: Big Number Playground uses the modern English short scale, where billion is 109 and each new “illion” is 1,000 times the previous one.
Explore related large numbers
Use the Big Number Explorer to convert any whole number to words, or continue with the large number names chart and the million, billion and trillion comparison.