Accutane (Isotretinoin) Dose & Duration Calculator
Estimate cumulative target dose and treatment length based on body weight and daily dose.
What this accutane calculator helps you estimate
This calculator is built to estimate three practical numbers people commonly ask about during isotretinoin treatment:
- Your approximate cumulative dose target in milligrams (mg).
- How strong your current dose is in mg/kg/day.
- How long treatment may take at a fixed daily dose.
Many dermatology plans reference a cumulative target around 120–150 mg/kg. Your dermatologist may choose a different strategy based on acne severity, side effects, relapse risk, prior treatments, and personal medical history.
How the formula works
1) Convert body weight to kilograms
If you enter pounds, the calculator converts to kilograms using: kg = lb × 0.453592.
2) Calculate cumulative target dose
The core formula is: Total target dose (mg) = body weight (kg) × target (mg/kg).
For a standard range, it calculates both:
- Lower target: weight × 120 mg/kg
- Upper target: weight × 150 mg/kg
3) Estimate time to complete treatment
Time is estimated as: days = total target dose ÷ daily dose. The tool also converts this into weeks and months for easier planning.
Why mg/kg/day matters
Besides total cumulative dose, clinicians look at daily intensity. A common dosing band is roughly 0.5 to 1.0 mg/kg/day, though real-world regimens may be lower or higher depending on tolerance and goals. If your number is outside that range, it does not automatically mean treatment is wrong—it simply means a closer conversation with your prescribing clinician is important.
Example
Suppose a patient weighs 70 kg and takes 40 mg/day:
- Daily intensity: 40 ÷ 70 = 0.57 mg/kg/day
- 120 mg/kg target: 70 × 120 = 8,400 mg
- 150 mg/kg target: 70 × 150 = 10,500 mg
- Estimated duration: about 210 to 263 days (~7.0 to 8.6 months)
How to use results responsibly
Bring these numbers to your follow-up visits
The calculator can improve your questions at appointments. Ask:
- What cumulative target are we aiming for?
- Should my daily dose change based on side effects?
- How does my response affect expected duration?
Do not self-adjust medication
Isotretinoin is a high-impact medication with important safety rules. Dose changes, missed doses, lab interpretation, and treatment pauses should be handled by your prescribing team.
Frequently asked questions
What if my dose changes mid-treatment?
That is common. In that case, total cumulative dose is calculated by adding each segment: (dose A × days A) + (dose B × days B) + .... Your clinician tracks this over time.
Does everyone need 120–150 mg/kg?
Not always. Some patients complete treatment at different cumulative exposures depending on response, tolerability, and physician judgment.
Can this calculator replace medical care?
No. It is an educational planning tool only and does not provide diagnosis, prescribing, or individualized medical advice.