PCR Master Mix Calculator
Reaction master mix volumes with pipetting excess, per-component breakdown and plate scaling.
How it works
Per-reaction component volumes are multiplied by the reaction count plus a pipetting excess, typically 5–10%, so that the final reaction still receives full volume after dead volume and tip retention losses. Component totals are reported alongside the per-reaction recipe.
Frequently asked questions
How much excess should I include in a PCR master mix?
Add 5–10% extra for most setups, and more when reaction volumes are small or the number of reactions is large. The excess covers liquid retained in tips, dead volume in the tube, and small pipetting inaccuracies that would otherwise leave the last few wells short. For a 96-well plate, preparing for 105 reactions rather than 96 is typical.
Why use a master mix instead of pipetting each reaction?
A master mix removes the largest source of well-to-well variation. Pipetting one small volume of each component into every tube compounds pipetting error across reactions; combining shared components once and dispensing a single larger volume means every reaction receives identical amounts. It is also faster and reduces contamination risk from repeated handling of stock reagents.