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Laboratory Dilution & Quantification

Master Mix & Reagent Excess Calculator

Scale a complete per-reaction recipe across samples and controls, with explicit excess and separately added components. Reconcile every reagent with the final reaction volume.

Biology · experimental measurements

Create a reagent ledger that distinguishes the shared master mix from components added separately to each reaction.

Private calculations in your browser · explicit inputs and model boundaries
Example preview · Samples and controlsOne complete reaction, component by component
Reagent A (shared)10 µL
Diluent (shared)8 µL
Sample or control (separate)2 µL

Segment proportions follow the entered per-reaction volumes. Preparation excess affects the batch quantity, not the composition of one reaction.

  1. 1EnterProvide the known values
  2. 2CalculateResults update automatically
  3. 3VerifyReview the details and units
Try an example

Enter values in %.

Enter values in µL.

One row per component: name, volume per reaction in µL, shared or separate. Include diluent explicitly. Separate components are counted without excess.

Calculation result

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Enter valid values to see the result.

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Understand the relationship

The reasoning behind the result

Build one reaction before scaling the batch

Vreaction = ΣVcomponent

A recipe must sum to its stated final reaction volume. The tool checks the sum before scaling, so a missing diluent or an extra component cannot silently change every reaction's composition.

The recipe contains entered volumes, not stock-to-target chemistry. Establish those volumes from your method first. This calculator does not select reagent concentrations, reaction conditions or a biological procedure.

Excess belongs to the shared preparation

Nprepare = Nactual(1 + e/100)

Percentage excess gives fractional reaction equivalents, which is useful when preparing a shared liquid mixture. An extra-equivalent allowance is an alternative way to describe the same preparation reserve. These modes are alternatives and are not compounded.

Separate additions such as different samples are multiplied by the actual number of reactions. The tool does not automatically increase the amount of every unique specimen because shared reagents have an allowance.

Dispense volume is not final reaction volume

The shared mix dispense per reaction is the sum of shared components. Add the separately listed components to reach the final volume. The remainder of the prepared shared mix is the planned allowance, not an additional amount to dispense into each reaction.

Controls may need a different separate addition from samples. The ledger gives aggregate quantities, not an instruction to substitute one specimen or control for another. Build separate batches if their shared recipes differ.

Follow the numbers

Ten 20 µL reactions

  1. Eight samples plus two controls make ten actual reactions. Ten percent excess gives eleven shared-mix equivalents.
  2. Shared components 10 + 8 = 18 µL per reaction require 110 µL reagent A and 88 µL diluent, totaling 198 µL.
  3. Dispense 18 µL shared mix into each of ten reactions and add 2 µL of the appropriate separate component. Shared excess remaining is 18 µL.

Actual reactions total 200 µL; shared preparation includes an additional 18 µL allowance.

Quick guide

How to use this calculator

  1. Count actual reactions, including controls.
  2. Enter the complete per-reaction recipe and mark shared versus separately added components.
  3. Choose a percentage or extra-reaction allowance for the shared mix.
  4. Check the recipe totals and dispense volume; separate components are reported for actual reactions only.

Calculation method

Calculation and interpretation

Create a reagent ledger that distinguishes the shared master mix from components added separately to each reaction.

N = samples + controls; shared multiplier = N(1 + excess/100) or N + extra; reagent total = per-reaction volume × its multiplier

Worked example

Ten 20 µL reactions

Actual reactions total 200 µL; shared preparation includes an additional 18 µL allowance.

N = samples + controls; shared multiplier = N(1 + excess/100) or N + extra; reagent total = per-reaction volume × its multiplier

Supported inputs

Precision and limits

Preparation arithmetic

Volumes are assumed additive and the stock uniformly mixed. The calculation does not choose a solvent, biological target, concentration, incubation condition or validated laboratory protocol. Check compatibility and the working range of the equipment separately.

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