How do you convert percent concentration to parts per million (PPM)?

• A. Multiply percent by 10,000.
• B. Divide percent by 10,000.
• C. Multiply percent by 1,000.
• D. Subtract percent from 100,000.

Answer: (A)

Percent concentration is parts per hundred, while ppm is parts per million. That means 1% equals 10,000 ppm, because 0.01 × 1,000,000 equals 10,000. So you multiply the percent value by 10,000 to get ppm. For example, 0.75% becomes 7,500 ppm. Dividing by 10,000 would give a much smaller number, multiplying by 1,000 would yield a result far too small, and subtracting from 100,000 isn’t a valid conversion.