Antibiotic Schedule Calculator
Generate a complete antibiotic dosing schedule with times and end date based on doses per day, start time, and course length.
How Antibiotic Timing Works
Antibiotics are not all the same — some work best when taken at evenly spaced intervals around the clock, while others simply need to be taken with or without food at roughly consistent times each day.
The core principle: maintaining therapeutic blood levels
Every antibiotic has a half-life — the time it takes for your body to eliminate half the drug from your bloodstream. To keep the drug working, your next dose must arrive before levels fall too low.
Spacing formula:
Interval (hours) = 24 ÷ doses per day
- Once daily (1×): every 24 hours
- Twice daily (2×): every 12 hours
- Three times daily (3×): every 8 hours
- Four times daily (4×): every 6 hours
Worked example:
You are prescribed amoxicillin 500 mg three times daily, starting at 8:00 AM.
- Dose 1: 8:00 AM
- Dose 2: 8:00 AM + 8h = 4:00 PM
- Dose 3: 4:00 PM + 8h = 12:00 AM (midnight)
Many people mistakenly take three-times-daily antibiotics at breakfast, lunch, and dinner — that leaves 5–6 hour gaps during the day and a 12+ hour gap overnight, which can allow bacteria to rebound.
Key tips:
- Never skip a dose — if you miss one, take it as soon as you remember unless the next dose is very close
- Complete the full course even if you feel better — stopping early breeds resistant bacteria
- Food interactions matter — some antibiotics (tetracyclines, fluoroquinolones) absorb poorly with dairy or antacids
- Alcohol can reduce effectiveness or worsen side effects with metronidazole and tinidazole
Set phone alarms for every dose interval — consistency is the most important factor in antibiotic success.