Erythromycin Dose Calculator (erythromycin ethylsuccinate) Weight (kg) Choose Erythromycin Strength Erythromycin 200 mg/5 mL Erythromycin 400 mg/5 mL Dose in millilitres Dose in milligrams For ages 1 month to 18 years only. Calculator written by Dr Jeremy Steinberg, GP. Contact for suggestions