How Many Zeros in a Quadrillion?
How many zeros in a quadrillion? A quadrillion has 15 zeros, written as 1,000,000,000,000,000 or 1015 in scientific notation. The short-scale system — used in the United States and modern British English — defines a quadrillion as one thousand trillion. It has five groups of three zeros beyond the initial 1, which is why counting them manually benefits from a double-check. Learn more about trillion zeros.
A quadrillion has
15
zeros
- Written Form
- 1 followed by 15 zeros
- Scientific
- 10¹⁵
Quadrillion's Position on the Short-Scale Ladder
The short answer: exactly 15 zeros. The prefix quadri- means four, referring to quadrillion's position as the fourth named step above a million on the short scale.
How Many Zeros Separate a Quadrillion from a Trillion?
A quadrillion is exactly 1,000 times larger than a trillion. A trillion has 12 zeros; a quadrillion has 15 — three additional zeros representing that factor of one thousand. See also: How many zeros in a sextillion.
If a trillion seconds is roughly 31,700 years, then a quadrillion seconds is closer to 31.7 million years.
- 1 quadrillion = 1,000 trillion
- 1 quadrillion = 1,000,000 billion
- 1 quadrillion = 1,000,000,000 million — a billion million
Quick Zero-Counting Trick
Count in groups of three after the leading 1: thousand, million, billion, trillion, quadrillion — each group adds three zeros to the last.
- Trillion
- 12 zeros —
1,000,000,000,000 - Quadrillion
- 15 zeros —
1,000,000,000,000,000 - Quintillion
- 18 zeros —
1,000,000,000,000,000,000
How to Write a Quadrillion
A quadrillion follows the same set of accepted forms as the other short-scale giants.
Standard, Scientific, and Shorthand Forms
- Standard form:
1,000,000,000,000,000 - Scientific notation:
1015 - Shorthand:
1 quadrillionis rarely abbreviated in finance, unlike million/billion/trillion, since figures rarely reach this scale outside of national and global accounting
Real-World References at the Quadrillion Scale
The total notional value of global derivatives markets has been estimated in the hundreds of trillions to low quadrillions of dollars. Cell counts across the human microbiome are also sometimes quoted near the quadrillion range. Learn more about how many zeros in a billion.
Zeros Comparison Table
| Name | Zeros | Written out |
|---|---|---|
| Trillion | 12 | 1,000,000,000,000 |
| Quadrillion | 15 | 1,000,000,000,000,000 |
| Quintillion | 18 | 1,000,000,000,000,000,000 |
How Many Zeros Does a Long-Scale Quadrillion Have?
In the long-scale numbering system — historically used across continental Europe — a quadrillion means something very different: 1024, or 1 followed by 24 zeros. The long scale defines each new "-illion" as a million times the previous one, rather than a thousand times, so a long-scale quadrillion equals what the short scale calls a septillion.
For practical purposes, if you're reading an English-language source published in the US or UK after the 1970s, "quadrillion" almost certainly refers to 15 zeros. The long-scale meaning has largely faded from everyday English use.
Zeros in a Quadrillion: FAQ
What comes before a quadrillion?
Quick answer
Hundred trillion (100,000,000,000,000) comes right before a quadrillion.
What comes after a quadrillion?
Quick answer
Ten quadrillion comes next, followed by hundred quadrillion and then quintillion.
How many digits does a quadrillion have?
A quadrillion has 16 digits in total — that's the digit 1 followed by 15 zeros.
How many zeros in 2 quadrillion? In 10 quadrillion?
Two quadrillion keeps the same 15 zeros — only the leading digit changes. Ten quadrillion adds one more, for 16 zeros total.
Is a 15-digit number always a quadrillion?
No. A 15-digit number ranges from 100,000,000,000,000 to 999,999,999,999,999 — that's hundreds of trillions, not a quadrillion. A quadrillion is the first 16-digit number.
How many zeros in a quadrillion in the British system?
Under the old British long-scale system, a quadrillion meant 1024 — nine more zeros than today's short-scale quadrillion. Modern British English now follows the short scale, so a quadrillion in the UK matches US usage at 15 zeros.