Understanding 1:10, 1:100, and 1:200 dilutions

By Remetric Labs · Last reviewed October 26, 2026

The one convention that matters

A ratio like 1:10 means 1 part stock in 10 parts total: 1 mL stock + 9 mL diluent = 10 mL. The common error is adding 1 mL to 10 mL (an 11 mL total, i.e. 1:11). Check every protocol for "to a final volume of" - that phrase confirms the total-volume convention used in the Dilution Calculator.

Worked numbers

1:10 of a 100 mg/mL stock: 100 ÷ 10 = 10 mg/mL. Make 100 mL: 10 mL stock + 90 mL diluent. 1:100: 100 ÷ 100 = 1 mg/mL; make 50 mL with 0.5 mL stock + 49.5 mL diluent (use a micropipette - a 0.5 mL error here is a 100% error). 1:200: 100 ÷ 200 = 0.5 mg/mL; make 200 mL with 1 mL stock + 199 mL diluent.

Serial dilutions

Two sequential 1:10 steps give 1:100 with better accuracy than pipetting 0.1 mL once: transfer 1 mL into 9 mL, mix, then 1 mL of that into a fresh 9 mL. Multiply the factors: 10 × 10 = 100-fold total. Dimensional analysis keeps units honest: (mg/mL × mL) ÷ mL = mg/mL.

Mistakes and limits

Pipetting below 1 µL, uncalibrated glassware, and temperature-dependent volumes all dominate error at high ratios - the math is exact but the transfer is not. Viscous stocks (glycerol) cling to tips; rinse or weigh instead. For concentration ↔ molarity bridges see mg/mL to molarity and the Molarity Calculator.