Cephalexin Pediatric Dose Calculator
Use this page when the search says cephalexin pediatric dose calculator. The main calculator route is the Keflex page because Keflex is the brand name used in the medication system.
Source alignedOfficial label plus pediatric dosing safety checks.
Calculator handoffUses the parent medication calculator with presets.
Review policyHow PedsCalc reviews dosing pages
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Use the prescribed plan first
This page explains formulation-specific dose support. It does not choose the child's medication, indication, dose target, frequency, duration, maximum dose, or allergy plan.
Accuracy boundary
The formula and example are for concentration conversion after a clinician has chosen the dose. The linked calculator still requires weight entry and final clinical verification.
Quick answer
- Cephalexin and Keflex use the same dose math.
- Cephalexin 125 mg/5 mL equals 25 mg/mL.
- Cephalexin 250 mg/5 mL equals 50 mg/mL.
- Choose the exact bottle strength before converting mg to mL.
Cephalexin formula
mL per dose = cephalexin mg per dose / mg per mL for the selected bottle.
- Use 25 mg/mL for 125 mg/5 mL suspension.
- Use 50 mg/mL for 250 mg/5 mL suspension.
Cephalexin suspension conversion
2.5 mL
62.5 mg with 125/5; 125 mg with 250/5
5 mL
125 mg with 125/5; 250 mg with 250/5
7.5 mL
187.5 mg with 125/5; 375 mg with 250/5
10 mL
250 mg with 125/5; 500 mg with 250/5
Worked example
- Example only: a clinician prescribes 40 mg/kg/day divided twice daily for a 20 kg child.
- 20 kg x 40 mg/kg/day = 800 mg/day.
- 800 mg/day / 2 doses/day = 400 mg per dose.
- With 250 mg/5 mL suspension, 400 mg / 50 mg per mL = 8 mL per dose.
Safety checks before measuring
- Match the label exactly because 125/5 and 250/5 are not interchangeable by mL.
- Review cephalosporin and immediate penicillin allergy history.
- Check renal adjustment guidance when kidney disease is relevant.
Frequently asked questions
Yes. Keflex is a brand name for cephalexin. The dose math depends on cephalexin mg and the exact product strength.
Use the Keflex calculator page. It is the cephalexin calculator in this medication system.