Chronic Migraine Calculator: Episodic or Chronic?
Enter your headache and migraine days to see whether you’re in the episodic or chronic range, and whether guidelines say prevention should be offered.
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Chronic migraine isn’t about how long you’ve had migraine. It’s about how many days a month you have headache. Getting the label right matters, because chronic migraine has its own treatment options and tends to be undertreated. Enter your numbers below to see where you land and whether guidelines say prevention should be on the table.
Loading the calculator. If it doesn’t appear, check that JavaScript is turned on. The guide below lets you work it out by hand.
How many migraine days is chronic migraine?
Under the International Classification of Headache Disorders (ICHD-3), chronic migraine means all three of these:
- Headache on 15 or more days a month
- On at least 8 of those days, the headache has migraine features, or is relieved by a triptan or ergot
- This has gone on for more than 3 months
Anything below that is episodic migraine. Researchers often split episodic migraine further by migraine days a month:
| Migraine days a month | Usual label |
|---|---|
| 0 to 3 | Low-frequency episodic migraine |
| 4 to 7 | Moderate-frequency episodic migraine |
| 8 to 14 | High-frequency episodic migraine |
| 15+ headache days (8+ migraine) | Chronic migraine |
When should you start migraine prevention?
The 2026 AAN and American Headache Society guideline says preventive treatment should be offered to adults with any of these:
- 4 or more migraine days a month
- 4 or more moderate to severe headache days a month
- Substantial disability from migraine
Plenty of people who qualify are never offered prevention. If you meet one of these, it’s fair to ask. Our guide to which preventives work best can help you prepare.
How to count your days accurately
Most people underestimate. A paper or app headache diary kept for 4 to 8 weeks gives you a much better number. Count any day with headache, even a mild one, and mark the days that felt like migraine or that you treated with a triptan.
Also note the days you take medicine for headache. Taking acute medicine on 10 or more days a month can make headaches more frequent, which our medication overuse headache checker can help you spot.
Frequently asked questions
How many migraine days a month is chronic?
Chronic migraine means headache on 15 or more days a month for more than 3 months, with at least 8 of those days being migraine. Fewer days than that is episodic migraine, even if attacks are severe.
Can episodic migraine turn into chronic migraine?
Yes. Every year a small share of people with episodic migraine move into the chronic range. Higher attack frequency, overusing acute medicine, poor sleep and depression are among the known risk factors, and many of them can be treated.
Can chronic migraine go back to episodic?
Yes, and it often does with treatment. Prevention, treating medication overuse and working on sleep and other factors can bring headache days back below 15.
Is chronic migraine the same as chronic daily headache?
Not quite. Chronic daily headache is a broad term for headache on 15 or more days a month from any cause. Chronic migraine is one type of it. Others include chronic tension-type headache and medication overuse headache.
Do I need a diagnosis of chronic migraine to get Botox?
In most places, onabotulinumtoxinA (Botox) is approved for chronic migraine specifically, so the label matters for access. Your doctor will usually want a headache diary to confirm the pattern.
More free migraine tools
- MIDAS CalculatorMigraine disability score from 5 questions about the last 3 months.
- HIT-6 CalculatorHeadache Impact Test score from 6 quick questions.
- Migraine Screening TestDo your headaches look like migraine? The 3-question ID Migraine.
- Chronic Migraine CalculatorEpisodic or chronic? Check your monthly headache days.
- Medication Overuse Headache CheckerRebound headache check against the ICHD-3 day limits.
- Preventive Response CalculatorPercent drop in migraine days, and is it a fair trial yet?
- Caffeine CalculatorTotal your daily caffeine and see where it lands for migraine.
- Visit Summary BuilderA one-page printable summary for your doctor or neurologist.
References
- Headache Classification Committee of the International Headache Society (IHS). The International Classification of Headache Disorders, 3rd edition. Cephalalgia. 2018;38(1):1-211. PubMed
- Potrebic S, Tanveer S, Becker WJ, et al. Pharmacologic treatment for migraine prevention in adults: practice guideline recommendations. Report of the AAN Guidelines Subcommittee and the American Headache Society. Neurology. 2026;107(7):e214881. doi:10.1212/WNL.0000000000214881
This tool is for education and to help you talk with your doctor. It doesn’t diagnose anything and isn’t medical advice. Your answers stay in your browser and are never sent to Cerebral Torque.
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