How It Works
This calculator works in 4 steps.
Enter the reported result
Type the value the instrument or assay reported.
Enter the manual predilution
Type the DF, ratio, or volumes of the dilution made before analysis.
Enter the instrument dilution
Type the onboard DF, if the analyzer reports values before its own correction. Enter 1 when the analyzer already corrects.
Read the corrected result
The calculator multiplies the reported value by both factors.
The Formula
The formula multiplies the reported result by the predilution factor and the instrument factor.
C_sample = C_reported × DF_pre × DF_instrumentDF_pre = (V_sample + V_diluent) / V_sample- C_sample:
- Corrected sample concentration
- C_reported:
- Value reported by the analyzer
- DF_pre:
- Manual predilution factor
- DF_instrument:
- Uncorrected onboard factor
Say you dilute serum 1:5 (50 µL + 200 µL saline). The analyzer then reports 1.8 mmol/L after its own step. The sample result is 1.8 × 5 = 9.0 mmol/L.
Conversion Table
The conversion table corrects 6 reported values for combined predilution and instrument factors (unit unchanged).
| Reported value | Predilution DF | Instrument DF | Total DF | Corrected value |
|---|---|---|---|---|
| 2.5 | 2 | 1 | 2 | 5 |
| 1.8 | 5 | 1 | 5 | 9 |
| 0.9 | 10 | 2 | 20 | 18 |
| 12 | 4 | 5 | 20 | 240 |
| 0.35 | 100 | 1 | 100 | 35 |
| 4.2 | 2 | 10 | 20 | 84 |
What Is the Sample Predilution Correction Calculator?
The Sample Predilution Correction Calculator is a tool that fixes a result when you diluted the sample by hand first. The calculator multiplies the result by your hand dilution factor. It also adds any dilution the machine or assay makes.
Analyzers know about their own dilution step. They do not know about the one you made by hand. An uncorrected predilution under-reports the result by the full predilution factor. The calculator keeps both factors separate in the record, so an auditor can see each correction.
Common Uses
There are 5 main uses of this calculator.
Clinical reruns
Lab staff correct samples diluted by hand after an over-range flag.
Low-volume samples
Technicians correct small samples diluted to reach the analyzer's minimum volume.
Viscous samples
Analysts correct viscous or high-protein samples diluted for accurate pipetting.
LC-MS sample preparation
Drug test labs correct for the solvent added to remove protein.
Audit trails
QA teams document each correction factor separately for review.