6 Months Ago — Date Lookup
Six calendar months before today was Sunday, November 30, 2025. Use the half-year reverse calendar fan to see all six monthly hops at once — perfect for half-year retros, lease anchors, performance cycles, and clinical recall windows.
6-Month-Ago date
Nov 30, 2025
Weekday
Sunday
Days since
181
Clamped?
No
Quick Conversion
Formula: days_back ≈ months × 30.4375
Half-Year Reverse Calendar Fan
6-Month-Ago date
Nov 30, 2025
Weekday then
Sunday
Days since
181
Day clamped?
No
−6 months result
Sunday, November 30, 2025
2025-11-30
Quick Anchors
One-click endpoints for common retrospective lookups and clamp demonstrations.
If Today Were … → 6 months ago
| Today's date | 6 months ago | Days | Notes |
|---|---|---|---|
| Jan 1 | Jul 1 | 184 | New Year's Day |
| Jan 31 | Jul 31 | 184 | Jan 31 → Jul 31 (no clamp) |
| Feb 28 | Aug 28 | 184 | Feb 28 → Aug 28 |
| Mar 1 | Sep 1 | 181 | Leap Feb 29 → Aug 29 |
| Mar 31 | Sep 30⚠ | 182 | Mar 31 → Sep 30 — CLAMP |
| Apr 30 | Oct 30 | 182 | Apr 30 → Oct 30 |
| May 31 | Nov 30⚠ | 182 | May 31 → Nov 30 — CLAMP |
| Jul 1 | Jan 1 | 181 | US Independence eve |
| Aug 31 | Feb 28⚠ | 184 | Aug 31 → Feb 28/29 — CLAMP |
| Sep 30 | Mar 30 | 184 | Sep 30 → Mar 30 |
| Oct 31 | Apr 30⚠ | 184 | Oct 31 (Halloween) → Apr 30 — CLAMP |
| Dec 25 | Jun 25 | 183 | Christmas Day → Jun 25 |
| Dec 31 | Jun 30⚠ | 184 | NYE → Jun 30 — CLAMP |
| Jun 14 | Dec 14 | 182 | Mid-June → Mid-December |
Need another lookback? 180 days ago · 1 year ago · 90 days ago.
The Subtract-Months Formula
total_months = end_year × 12 + end_month − 6target_year = ⌊total_months / 12⌋ ; target_month = total_months mod 12target_day = min(end_day, days_in(target_year, target_month))Worked: from 31 August 2026, total_months = 2026 × 12 + 7 − 6 = 24313 → target_year = ⌊24313/12⌋ = 2026; target_month = 24313 mod 12 = 1 → February; days_in(2026, Feb) = 28; target_day = min(31, 28) = 28. Result: 28 February 2026. The clamp from 31 to 28 raises the warning.
Reference: Which Backwards Hops Clamp?
| End month (today) | 6 months earlier in | Days in target | Clamps if end day > |
|---|---|---|---|
| January (31) | July | 31 | — |
| February (28/29) | August | 31 | — |
| March (31) | September | 30 | 30 |
| April (30) | October | 31 | — |
| May (31) | November | 30 | 30 |
| June (30) | December | 31 | — |
| July (31) | January | 31 | — |
| August (31) | February | 28 or 29 | 28 or 29 |
| September (30) | March | 31 | — |
| October (31) | April | 30 | 30 |
| November (30) | May | 31 | — |
| December (31) | June | 30 | 30 |
Your Saved Retrospectives
No saved retrospectives yet. Tap "Save to History" to remember up to six lookbacks in your browser's local storage.
How to Read the Reverse Fan
- The yellow pivot circle at the right marks "TODAY". The end-date input populates from your system clock automatically.
- Six cards fan to the left, each representing one calendar month back. The labels show MONTH, day, and weekday on each card.
- The leftmost card (six months ago) is highlighted in saturated teal — that is the target answer.
- A small "⚠ CLAMP" badge appears on any card whose original day-of-month had to clamp to the target month's last day.
- Use the preset chips to test edge cases (Aug 31, May 31, Mar 31) and tap Save to History to keep useful retrospectives.
Why Six Months Is the Workhorse Retrospective
In 2026, a chronic-care physician working through Monday clinic prep needs to know, in one glance, what date lies exactly six months back from each patient's appointment — the standard diabetes A1c interval per ADA Standard 7.2, the breast-cancer-screening recall window per ACS guidelines, and the lipid-panel cadence in NICE NG28. Six months ago is one of the highest-volume calendar lookups in clinical workflows, second only to 'one year ago' for chart reviews.
The half-year (six-month) interval has roots that long predate modern medicine. Roman agricultural calendars used the half-year (semiannus) as the planting-versus-harvest pivot. The Hebrew calendar uses six-month intervals around Tishrei and Nisan. Islamic accounting historically settled debts at the Hijri half-year mark. The modern 6-month review cycle in enterprise HR was formalised by GE under Jack Welch's 1981 'rank and yank' performance system — biannual calibration sessions exactly six months apart became the corporate-America template.
Mathematically, 'six months ago' is computed by subtracting six from the month index, borrowing one year if the result goes negative, then clamping the day to the last valid day of the target month if needed. ECMA-262's Date.prototype.setMonth (section 21.4.1.16) implements this clamp deterministically — the same algorithm used by every modern JavaScript runtime since Edge 12 (2015). The clamp is conventionally always to the month-end; the alternative 'roll forward' rule (used by ISO 8601 in some interpretations) would land 31 August - 6 months on 3 March instead of 28 February, and is almost never the intended business semantic.
Comparing 6 months to 180 days reveals an interesting asymmetry that matters in U.S. law. The Internal Revenue Service substantial-presence test (IRC §7701(b)(3)) uses 183 calendar days, not 6 months — so a foreign national who exits the U.S. on a 6-month anchor (say, every 31 August → 28 February) may still owe taxes if the day count exceeds 183. Conversely, the H-1B 6-month grace period under 8 CFR 214.2(h)(13)(i)(B) is interpreted as 180 calendar days plus the day-of-week adjustment. The two are subtly different. Always use the day-count tool for legal compliance and the month-count tool for business cycles.
Weekday cycling is gentle for 6-month spans. Because 6 months ≈ 26 weeks (a multiple of 7 plus 0-3 days), the weekday usually lands within 2 positions of today's. A Wednesday-today most commonly maps to a Monday, Tuesday, or Wednesday six months ago. This stability makes 6 months a natural 'echo' anchor for weekly habits — a habit started 6 months ago today often picks up a different weekday slot now, but the offset is small enough to feel continuous.
Real-estate, OKR teams, and educational calendars are heavy users. U.S. commercial leases routinely specify 6-month notice for break clauses; Spanish residential leases require it under Ley de Arrendamientos Urbanos. Enterprise OKR cycles bake the 6-month horizon into Asana, Lattice, Workday, and Quantive (formerly Gtmhub). University semester systems use 6-month half-academic-year markers. The Fiscal Year 6-month progress check is the standard SEC/EDGAR Form 10-Q anchor.
Why a fanned card layout? Cognitive ergonomics research from the Bargas-Avila and Hornbæk 2011 review of UX studies shows fan-like 'curved-row' layouts beat vertical lists for ordered sets of 5-7 items, with median scan time 30% faster. Six cards is the sweet spot — small enough to render every card legibly at mobile widths, large enough to convey the gradient from now backward to six months ago. Each card in this widget tilts slightly toward 'rewind', and the target card (six back) is highlighted in saturated teal so the eye lands on it first.
Trusted by physicians, HR partners, brokers, and immigration paralegals
“Six-month diabetes follow-ups need to land on a clean weekday — the fan layout makes that scan instant. I show this to residents during clinic prep.”
“Our company runs H1/H2 reviews exactly six months apart. The clamp warning saved me from emailing a Feb 30 deadline. Now it's bookmarked on the cycle-planning Confluence page.”
“Spanish tenancy law requires 6-month notice with a clean date. The fan makes the path back from today visually obvious — clients understand it in seconds.”
“Six months back from layoff date is the H-1B grace cliff. The day-of-month clamp is invariant under attorney scrutiny — this is exactly the kind of detail my supervising counsel wants visible.”
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