Antibiotic & Media Additives — Free Lab Calculators

What this is for: For a batch of medium or culture, computes how many µL of each antibiotic/additive stock to add to hit the working concentration.

The formula: µL of stock = working concentration × culture volume (mL) ÷ stock concentration (units converted within each family)

How to use:

Enter the culture / media volume (mL).
For each additive (ampicillin, kanamycin, chloramphenicol, tetracycline, puromycin, IPTG, X-gal), check or edit its stock concentration and unit and its working concentration and unit — all concentrations are editable.
Read the µL of stock to add for each additive.
Add antibiotics to cooled media (< 55 °C) or to liquid culture just before use.

Antibiotics & Media Additives — stock to culture

All concentrations are editable — check your supplier's recommendations. µL of stock to add = working conc × culture volume / stock conc. Units convert automatically within the mass family (mg/mL, µg/mL, ng/mL) or the molar family (M, mM, µM, nM) — never mix them.

Culture / media volume (mL)

Ampicillin — stock conc. / unit

Ampicillin — working conc. / unitµL of stock to add: — Plates/liquid for ampR plasmids; stock in water, -20 °C

Kanamycin — stock conc. / unit

Kanamycin — working conc. / unitµL of stock to add: — Stock in water, -20 °C

Chloramphenicol — stock conc. / unit

Chloramphenicol — working conc. / unitµL of stock to add: — Stock in ethanol

Tetracycline — stock conc. / unit

Tetracycline — working conc. / unitµL of stock to add: — Stock in ethanol; light-sensitive

Puromycin — stock conc. / unit

Puromycin — working conc. / unitµL of stock to add: — Mammalian selection; dose varies by cell line (1-10 µg/mL)

IPTG — stock conc. / unit

IPTG — working conc. / unitµL of stock to add: — Inducer; 0.1-1 mM typical

X-gal — stock conc. / unit

X-gal — working conc. / unitµL of stock to add: — Blue-white screening; stock in DMF

Prefer to work offline or keep a copy? The download link is right below.
Download the Antibiotic & Media Additives workbook (.xlsx)

Notes & limits (from the workbook): All concentrations are editable — check your supplier's recommendations. µL of stock to add = working conc × culture volume / stock conc. Units convert automatically within the mass family (mg/mL, µg/mL, ng/mL) or the molar family (M, mM, µM, nM) — never mix them; a stock and working concentration from different families give no result. Add antibiotics to cooled media (< 55 °C) or to liquid culture just before use.