Antibiotic Stock Solution Calculator
💊 Antibiotic Preparation Protocol
Stock Volume to Add to Media
—
Antibiotic Mass Needed
—
mg to weigh
Solvent Volume
—
mL to dissolve in
Dilution Factor
—
stock → working
Final Working Conc.
—
µg/mL in media
Step-by-Step Protocol
How to Use the Antibiotic Stock Solution Calculator
Select an antibiotic preset to auto-fill standard values, or enter custom concentrations. The calculator outputs the mass to weigh, solvent volume for the stock, and the volume of stock to add to your media.
- Stock Concentration: Concentration of the prepared stock solution (mg/mL). Common stocks are 50–100 mg/mL.
- Working Concentration: Final antibiotic concentration in the culture media (µg/mL).
- Media Volume: Total volume of media you are preparing (mL).
- Solvent: Use the solvent appropriate for your antibiotic — water for most, ethanol for chloramphenicol and tetracycline.
Antibiotic Stock Solution Formula
Mass (mg) = Stock Conc. (mg/mL) × Stock Volume (mL)
Stock to Add (µL) = Working Conc. (µg/mL) × Media Vol. (mL) / Stock Conc. (µg/mL)
Example — Ampicillin:
Stock = 100 mg/mL, Working = 50 µg/mL, Media = 500 mL
Mass = 100 mg/mL × 10 mL = 1000 mg (1 g)
Stock to Add = 50 × 500 / 100,000 = 0.25 mL (250 µL)
Stock to Add (µL) = Working Conc. (µg/mL) × Media Vol. (mL) / Stock Conc. (µg/mL)
Example — Ampicillin:
Stock = 100 mg/mL, Working = 50 µg/mL, Media = 500 mL
Mass = 100 mg/mL × 10 mL = 1000 mg (1 g)
Stock to Add = 50 × 500 / 100,000 = 0.25 mL (250 µL)
Common Antibiotic Working Concentrations
- Ampicillin: 50–100 µg/mL — dissolve in sterile water, store at −20°C
- Kanamycin: 50 µg/mL — dissolve in sterile water, store at −20°C
- Chloramphenicol: 34 µg/mL — dissolve in 100% ethanol, store at −20°C
- Tetracycline: 10 µg/mL — dissolve in 70% ethanol, protect from light
- Streptomycin: 50 µg/mL — dissolve in sterile water, store at −20°C
- Gentamicin: 10 µg/mL — dissolve in sterile water, store at 4°C