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Count headache days, migraine-feature days, and acute medication days over a 7–31 day diary window. The tool scales to 30-day equivalents so short diaries compare to monthly clinical benchmarks, then applies teaching snapshots for high-frequency episodic migraine (HFEM), chronic migraine day-count themes, and simplified medication-overuse discussion flags. Pair with our migraine trigger score calculator and pain scale assessment. Not ICHD-3 diagnosis, not drug-class MOH rules, not emergency triage.
Last updated: June 5, 2026
Preventive therapy, disability scoring, and imaging decisions require clinician assessment. This tool quantifies how often attacks occur—not peak intensity, aura type, or secondary causes.
Count any day you took acute meds specifically for this headache problem (Rx or OTC).
Headache d / 30
6
Migraine d / 30
4
Acute Rx/OTC d / 30
5
Headache-day band (teaching)
Moderate episodic headache-day burden
Moderate episodic burden: headache days are in a mid range per 30-day equivalent—useful interval to review lifestyle factors and acute medication use with a clinician.
Thunderclap onset, fever, stiff neck, focal neurologic signs, or new worst headache = emergency evaluation, not frequency math.
Default — 30 d, 6 / 4 / 5 days
6 / 4 / 5
H / M / med per 30 d — moderate episodic
Low episodic — 30 d, 2 / 1 / 1
2 / 1 / 1
Infrequent burden band
HFEM snapshot — 30 d, 10 / 9 / 6
10 / 9 / 6
≥8 migraine d, <15 headache d
Chronic CM snapshot — 30 d, 16 / 10 / 14
16 / 10 / 14
≥15 H + ≥8 M + high med days
Weekly bridge example: 3 headache days in 7 days → (3 ÷ 7) × 30 ≈ 12.9 headache days per 30-day equivalent.
30-day equivalent = (days in window ÷ window length) × 30. Each counter—headache days, migraine-feature days, acute medication days—uses the same scaling.
Headache: (6 ÷ 30) × 30 = 6 days per 30-day equivalent
Migraine-feature: (4 ÷ 30) × 30 = 4 days per 30-day equivalent
Acute medication: (5 ÷ 30) × 30 = 5 days per 30-day equivalent → moderate episodic headache-day band
| Counter | Counting rule |
|---|---|
| Headache day | Any calendar day with qualifying headache lasting your usual minimum (often ≥30 min for migraine diaries) |
| Migraine-feature day | Subset of headache days meeting your migraine definition (unilateral, pulsating, nausea, photophobia, etc.)—must be ≤ headache days |
| Acute medication day | Any day you took Rx or OTC medication specifically for headache (triptan, NSAID, acetaminophen, combo product) |
| One day = one count | Multiple doses or attacks on the same calendar day still count as one headache day and one medication day |
| Band | Headache days / 30 equiv | Clinical teaching |
|---|---|---|
| None | 0 | No headache days logged in the window—verify diary completeness. |
| Low episodic | 1–3.9 | Infrequent attacks; still track triggers, prodrome, and acute response. |
| Moderate episodic | 4–7.9 | Mid-range burden—good interval to review lifestyle and acute medication patterns. |
| High-frequency episodic (headache days) | 8–14.9 | Frequent headache days without crossing chronic headache-day threshold—prevention discussions common if disabling. |
| Very high headache-day burden | ≥15 | Chronic headache-day load on this snapshot—evaluate MOH, red flags, and secondary causes clinically. |
| Criterion | ICHD-3 requirement | This calculator |
|---|---|---|
| Headache frequency | Headache on ≥15 days/month for >3 months | Flags when 30-day equivalent headache days ≥15 (single-window snapshot only) |
| Migraine phenotype on headache days | On ≥8 days/month, headache has migrainous features | Flags when 30-day equivalent migraine-feature days ≥8 |
| Duration | Pattern present ≥3 months | Not assessed—prospective diary required |
| Not better accounted for by another ICHD-3 diagnosis | Clinician judgment | Not assessed |
| Drug class | ICHD-3 day threshold | Teaching note |
|---|---|---|
| Ergots, triptans, opioids, combination analgesics | ≥10 days/month for >3 months | High-risk pattern for medication-overuse headache discussions |
| Simple analgesics (acetaminophen, NSAIDs) | ≥15 days/month for >3 months | Lower threshold than triptans but still meaningful when headache frequency is high |
| Caffeine (from any source) | Often counted within combination/overuse frameworks | Track energy drinks, Excedrin-type products, and coffee used for headache |
| This calculator flag | ≥10 acute medication days per 30-day equivalent with ≥4 headache days | Prompts medication review—not substance-specific MOH diagnosis |
30-day equivalents: 16 headache / 10 migraine / 14 medication days
Crosses chronic migraine day-count snapshot (≥15 headache + ≥8 migraine) and medication-overuse teaching flag — still requires 3-month duration and clinician phenotype documentation for formal diagnosis.
Normalized burden crosses a chronic-migraine-style day-count snapshot (about ≥15 headache days and ≥8 migraine-feature days per 30 days). This is not a diagnosis—confirm with a headache specialist and a prospective diary. Acute medication use is also high on this snapshot—bring an exact medication list (including OTC) to discuss medication-overuse headache risk.
Headache: (3 ÷ 7) × 30 = 12.9 per 30-day equivalent
Migraine: (2 ÷ 7) × 30 = 8.6 per 30-day equivalent
Medication: (2 ÷ 7) × 30 = 8.6 per 30-day equivalent
Short windows help patients who only tracked one week still orient to monthly benchmarks for clinic intake—assuming the week is representative.
Education only. Not for ICHD-3 coding, preventive prescribing, MOH diagnosis by drug class, or emergency triage. Thunderclap headache, fever with stiff neck, focal neurologic deficits, or pregnancy with severe headache require urgent evaluation—not frequency math.
For neurology education, primary care, and headache diary teaching