PPB Calculator

The Deep End of Trace Analysis

For most common chemistry applications, Parts Per Million (PPM) is precise enough. But when measuring extremely dangerous toxins, heavy metals, or highly potent pharmaceuticals, PPM isn't granular enough. We must drop down to Parts Per Billion (PPB).

One PPB means there is exactly one unit of a target substance for every one billion units of the total mixture.

• 1 PPB is equivalent to exactly one drop of ink inside an Olympic-sized swimming pool.
• 1 PPB is equivalent to one second out of nearly 32 years.

Calculating PPB

The calculation is identical to PPM, except you multiply the final ratio by one billion ($10^9$) instead of one million.

For dilute aqueous (water-based) solutions, there is a handy shortcut: $1 \, \text{PPB}$ is exactly equivalent to $1 \, \text{microgram}$ of solute per $1 \, \text{Liter}$ of water ($\mu g / \text{L}$).

The Formula

Example Calculation

A city water utility tests a massive $5,000 \, \text{kg}$ reservoir tank and discovers it contains exactly $10 \, \text{milligrams}$ of arsenic. What is the concentration in PPB?

1. Convert to matching units (grams):
   • $10 \, \text{mg} = 0.01 \, \text{g}$.
   • $5,000 \, \text{kg} = 5,000,000 \, \text{g}$.
2. Divide Solute by Total: $0.01 / 5,000,000 = \mathbf{0.000000002}$.
3. Multiply by 1 Billion ($10^9$): $0.000000002 \cdot 1,000,000,000 = \mathbf{2 \, \text{PPB}}$.

The water contains $2 \, \text{PPB}$ of arsenic.