A billion is a thousand million
A million is 106 (6 zeros) and a billion is 109 (9 zeros), so a billion is a thousand millions. To turn millions into billions, divide by 1,000: 394,000 million is 394 billion. The easy check is the zero count — billion has 9, not 8.
Quick reference
| Millions | Billions | Scientific |
|---|---|---|
| 500 million | 0.5 | 5 × 108 |
| 1,000 million | 1 | 1 × 109 |
| 2,500 million | 2.5 | 2.5 × 109 |
| 10,000 million | 10 | 1 × 1010 |
| 100,000 million | 100 | 1 × 1011 |
| 1,000,000 million | 1,000 | 1 × 1012 (= 1 trillion) |
A "unicorn" startup is one valued at a billion dollars — that is 1,000 million. Once you pass 1,000,000 million you have reached a trillion.
The one thing to watch
- Short scale vs long scale. Modern usage puts a billion at 109 (a thousand million). Some old European texts used "long scale," where a billion meant a million million (1012). Everything financial and scientific today uses the short scale.
- Don't drop a zero. Million has 6 zeros, billion has 9. The common slip is writing a billion as 100,000,000 (8 zeros) instead of 1,000,000,000.
- Lakhs and crores. In the Indian system, 1 crore = 10 million and 100 crore = 1 billion. Same number, different grouping.
Common questions
How many millions are in a billion?
Exactly 1,000. A billion is a thousand million, so 500 million is 0.5 billion and 2,500 million is 2.5 billion.
How do I convert millions to billions?
Divide by 1,000. To go from billions back to millions, multiply by 1,000. It is just shifting the decimal three places.
How many millions is a crore, and how does that fit?
One crore is 10 million, so 100 crore equals 1,000 million, which is 1 billion. The Indian numbering system groups digits differently, but the underlying number is the same.
