How It Works
This calculator works in 4 steps.
Enter the expected concentration
Type the nominal or back-calculated value of the dilution.
Enter the measured concentration
Type the instrument result, corrected for any dilution in the measurement.
Set the acceptance limits
Type the low and high recovery limits from the method.
Read recovery and the flag
The calculator returns percent recovery, bias, and pass or fail.
The Formula
The formula divides the measured concentration by the expected concentration.
%R = 100 × C_measured / C_expected% bias = %R − 100%R_i = 100 × (C_i × DF_i) / C_neat- C_measured:
- Measured concentration
- C_expected:
- Expected concentration
- DF_i:
- Dilution factor of level i
- C_neat:
- Undiluted reference value
A 10 ng/mL dilution that reads 10.6 ng/mL has 106% recovery and +6% bias.
Conversion Table
The conversion table gives recovery and bias for 6 expected and measured pairs, checked against 80% to 120% limits.
| Expected | Measured | Recovery | Bias | Check |
|---|---|---|---|---|
| 10 | 9.8 | 98% | -2% | Within 80–120% |
| 10 | 10.6 | 106% | 6% | Within 80–120% |
| 50 | 44.5 | 89% | -11% | Within 80–120% |
| 1 | 1.18 | 118% | 18% | Within 80–120% |
| 100 | 97.2 | 97.2% | -2.8% | Within 80–120% |
| 5 | 3.9 | 78% | -22% | Outside 80–120% |
What Is the Dilution Recovery Calculator?
The Dilution Recovery Calculator is a tool that compares a measured concentration with the expected concentration of a dilution and returns percent recovery and bias. Recovery equals measured divided by expected, times 100.
Recovery checks show whether a dilution and the measurement agree. Acceptance limits come from the method: many bioanalytical methods accept 85% to 115%, and many immunoassay dilution linearity checks accept 80% to 120%. The user sets the limits, and the calculator flags each result.
Common Uses
There are 5 main uses of this calculator.
Dilution linearity
Validation teams test recovery across serial dilutions of one sample.
Spike recovery
Analysts check accuracy in sample matrices.
Standard verification
Labs verify a new standard against an old one.
Instrument checks
Users confirm instrument response after maintenance.
Troubleshooting
QC teams locate a dilution or measurement fault.