How It Works
This calculator works in 4 steps.
Choose the basis
Select µg/L (w/v) or µg/kg (w/w).
Enter the stock concentration
Type the stock in ppm or ppb; the calculator converts ppm × 1,000.
Enter the target ppb and volume
Type the trace-level target and the final volume.
Read the stock volume
The calculator returns V₁ in µL and suggests an intermediate step, if the factor exceeds 1,000.
The Formula
The formula applies C₁V₁ = C₂V₂ after converting both concentrations to ppb.
ppb₁ × V₁ = ppb₂ × V₂1 ppb = 1 µg/L = 1 ng/mL1 ppm = 1,000 ppb- ppb₁ / ppb₂:
- Stock and target in ppb
- V₁ / V₂:
- Stock and final volumes
To make 100 mL of 10 ppb lead from a 1 ppm (1,000 ppb) stock, V₁ = 10 × 100 / 1,000 = 1 mL (1,000 µL).
Conversion Table
The conversion table lists stock volumes in µL for 6 trace-level dilutions.
| Stock | Target | Final volume | Stock volume | DF |
|---|---|---|---|---|
| 1 ppm | 10 ppb (10 µg/L) | 100 mL | 1,000 µL | 100 |
| 10 ppm | 50 ppb (50 µg/L) | 100 mL | 500 µL | 200 |
| 1,000 ppb | 5 ppb (5 µg/L) | 50 mL | 250 µL | 200 |
| 100 ppm | 1 ppb (1 µg/L) | 1,000 mL | 10 µL | 100,000 |
| 1 ppm | 0.5 ppb (0.5 µg/L) | 500 mL | 250 µL | 2,000 |
| 500 ppb | 20 ppb (20 µg/L) | 250 mL | 10,000 µL | 25 |
What Is the PPB Dilution Calculator?
The PPB Dilution Calculator is a tool that dilutes trace-level solutions expressed in parts per billion (ppb) on a defined basis, such as µg/L in water or µg/kg in solids. One ppb equals 1 µg/L in dilute aqueous solutions and equals 0.001 ppm.
ppb dilutions reach the levels of drinking water limits, such as the United States Environmental Protection Agency (EPA) action level of 15 ppb for lead. At ppb levels, contamination from glassware, water, and acid matters as much as the arithmetic. The calculator flags dilution factors above 1,000 and suggests a 2-stage plan.
Common Uses
There are 5 main uses of this calculator.
Drinking water testing
Water labs prepare lead, arsenic, and uranium standards near regulatory limits.
ICP-MS calibration
Analysts build 0.1 to 100 ppb calibration sets.
Pesticide residue analysis
Food labs prepare µg/kg matrix standards.
Semiconductor QC
Fabs test ultrapure chemicals at ppb levels.
Spike solutions
Labs prepare ppb spikes for recovery checks.