DF = Final Volume / Sample Volume
Dilution factor (DF) = total volume / sample volume = (sample + diluent) / sample. A 1:10 dilution means 1 part sample + 9 parts diluent = DF of 10. To find final concentration: C_final = C_original / DF. For serial dilutions, total DF = product of individual DFs. When reporting results, multiply the measured value by the DF to get the original concentration. Common lab dilutions: 1:2 (equal parts), 1:10 (100 µL + 900 µL), 1:100 (10 µL + 990 µL). Always account for dilution factor when calculating cell counts, absorbance readings, or analyte concentrations from diluted samples.