How It Works
This calculator works in 4 steps.
Enter the measured concentration
Type the instrument reading for the diluted sample.
Enter the dilution
Type DF directly, a ratio such as 1:9, or the sample and final volumes.
Convert to DF
The calculator turns ratios and volumes into a single DF.
Read the original concentration
The calculator multiplies the measured value by DF.
The Formula
The formula multiplies the measured concentration by the dilution factor.
C_original = C_measured × DFDF = V_final / V_sample- C_original:
- Concentration of the undiluted sample
- C_measured:
- Concentration read on the diluted sample
- DF:
- Dilution factor
- V_sample / V_final:
- Sample and final volumes
A protein sample diluted 1:10 reads 0.45 mg/mL. The original concentration is 0.45 × 10 = 4.5 mg/mL.
Conversion Table
The conversion table shows the original concentration for 6 measured values and dilution factors.
| Measured (diluted) | DF | Original concentration |
|---|---|---|
| 0.45 mg/mL | 10 | 4.5 mg/mL |
| 12.5 µg/mL | 50 | 625 µg/mL |
| 3.2 mM | 100 | 320 mM |
| 0.82 g/L | 2 | 1.64 g/L |
| 150 ng/mL | 20 | 3,000 ng/mL |
| 7.7 µM | 1,000 | 7,700 µM |
What Is the Reverse Dilution Calculator?
The Reverse Dilution Calculator is a tool that finds a sample's first strength from a reading taken after you diluted it. It multiplies the reading by the dilution factor you used.
Labs often dilute a sample so it fits the range of the instrument. The instrument then reports the diluted value. The reverse calculation restores the value that belongs to the original sample. You can enter a DF, a ratio or two volumes. The result uses the same unit as your reading.
Common Uses
There are 5 main uses of this calculator.
Over-range samples
Analysts correct samples diluted to fall within the calibration curve.
Protein quantification
Biochemists correct BCA and Bradford readings for sample dilution.
Water and effluent testing
Water labs correct diluted waste water readings.
Clinical results
Clinic machines multiply auto-diluted results by DF.
QC reporting
QC teams report undiluted values on certificates of analysis.