Article — 6 Month Calculator
6 month calculator: what date is 6 months from today?
A 6 month calculator adds or subtracts six months from a date. Six calendar months from today is the same day of the month, six positions later — November 13, 2026 if today is May 13, 2026 (a Friday). Counted as 180 days, the result is November 9, 2026. The two methods diverge by 1 to 4 days depending on which months are involved.
The calculator at the top of this page handles forward and backward counting with quick presets for 1, 3, 6, 9, and 12 months. The article below covers where the number six shows up in everyday life — passport rules, probation periods, insurance terms — and the legal difference between "six months" and "180 days" that most people never notice.
What is 6 months from today?
If today is May 13, 2026, six calendar months from today is November 13, 2026, a Friday. The calculation keeps the same day-of-month and shifts the calendar forward by six positions. Change the start date in the calculator to get the answer for any other day.
The default in the calculator is 180 days, the common shorthand for "half a year." For May 13, 2026, that lands on November 9, 2026 — four days earlier than the six-calendar-months answer. Either method is reasonable depending on context. Contracts that say "six months" usually mean calendar months; statutes that say "180 days" mean exactly 180 days.
How many days is 6 months?
Six calendar months is not a fixed number of days. The answer ranges from 181 to 184 depending on which months are included. The minimum is 181 days, hit when the span starts in a 30-day month that runs into February (September through March in a non-leap year). The maximum is 184 days, reached over six summer months like March through September.
The two methods are 1 to 4 days apart. In most personal contexts the difference is irrelevant. In legal and financial contexts it matters. A statute that gives you "180 days" to file gives you exactly 180 days. A clause that says "six months" gives you six calendar months under the corresponding-day rule, which can mean one to four extra days.
Calendar months versus 180 days
US federal law spells out the difference. Under 29 CFR 4000.43, a period measured "in months" runs to the corresponding day of the target month — six months from March 15 is September 15, regardless of how many days that span actually contains. A period measured "in days" runs exactly that many days.
Some statutes use the day count specifically to remove ambiguity. The Equal Employment Opportunity Commission gives complainants 180 days — not "six months" — to file a discrimination charge under federal law. The deadline extends to 300 days where a state Fair Employment Practices Agency exists. The use of "180 days" instead of "six months" was deliberate; it eliminates the corresponding-day question.
US courts have long applied a 'corresponding-day rule' for six-month periods in real-estate contracts. State courts mostly follow the same convention, though a handful interpret "month" as 30 days when the contract is ambiguous.
The 6-month passport validity rule
More than 70 countries — including China, Thailand, Brazil, Indonesia, and most of the Schengen Area's external partners — require a visitor's passport to be valid for at least six months beyond the date of entry. If your passport expires sooner, the airline can refuse boarding at check-in and the border officer can deny entry on arrival.
The rule catches travellers off guard because the relevant date is the entry date, not the booking date or the return date. A passport that expires on November 1 stops you from entering a six-month-rule country any time after May 1, even if you plan to return well before the expiry. The US State Department recommends renewing passports nine months before expiry to stay comfortably inside the buffer.
The six-month clock starts at the date you enter the country, not the date you leave it. A passport that is valid through the entire trip but expires four months later still fails the rule. Use the calculator with your entry date as the start to find the earliest acceptable passport expiry date.
Probation, insurance, and employment
Six months is the most common length for an employment probationary period across the EU. In Germany the statutory maximum is six months. In France, the standard période d'essai for managerial roles is four months, renewable to eight in some cases. The UK has no statutory limit but most employers use either three or six months. In the US there is no federal rule on probation length — Montana is the exception, requiring at least six months before "good cause" protections apply.
US car insurance is mostly sold in six-month terms. GEICO, Progressive, and State Farm all default to six-month policies rather than annual ones. The shorter term lets insurers reprice on the basis of fresh driving history — a single ticket or claim can lift the next premium without waiting twelve months. It also lets drivers shop around more often.
- EU probation: six months is the maximum allowed in most member states
- Auto insurance: six-month terms are the US default at the largest carriers
- Dental check-up: every six months is the traditional ADA cadence
- Tire rotation: six months or 10,000 km, whichever comes first
- Smoke alarm test: NFPA recommends battery testing twice a year
- SNAP recertification: six months between paperwork cycles for most US recipients
- Lease renewals: 60 to 90 days' notice before the end of a six-month term is the common ask
- Mid-term rental: the three-to-six-month bucket is dominated by relocations and remote workers
Counting six months backward
To find a date six months earlier, switch the calculator to "Months before." Six months before October 15, 2026 is April 15, 2026 — the same calendar date six months back. The end-of-month rule applies in reverse: six months before March 31, 2026 is September 30, 2025, since September only has 30 days.
Backward counting matters whenever a known future date triggers a deadline. Visa applications, marriage banns, mortgage rate locks, and many medical follow-ups carry "six months prior" requirements. The US tax filing extension, for example, runs six months from the original April deadline to October 15.
For "six months ago" headlines, the calculator's backward toggle gives the exact corresponding-day date. May 13, 2026 minus six months is November 13, 2025. The day-of-week is shown so you can match the result against memories or records that reference the weekday.
End-of-month edge cases
Adding six months to a date near the end of the month occasionally produces a "day that does not exist." August 31 plus six months would notionally be February 31, but February has 28 days (29 in a leap year). The standard rule, used by US courts and the JavaScript Date API after clamping, is to roll back to the last valid day of the target month. August 31 plus six months is February 28 in a non-leap year and February 29 in a leap year.
Aug 31, 2026 + 6 months → Feb 28, 2027Aug 31, 2027 + 6 months → Feb 29, 2028 (leap)Mar 31, 2026 + 6 months → Sep 30, 2026May 31, 2026 + 6 months → Nov 30, 2026Dec 31, 2026 + 6 months → Jun 30, 2027The clamping rule applies in both directions. Six months before March 31 is September 30, not "September 31." The calculator handles this automatically, so the result is always a real calendar date.
Common 6-month mistakes
Treating "six months" as exactly 180 days. Six calendar months range from 181 to 184 days. The legal default is calendar months, not the day count. If a contract uses "180 days" specifically, take it literally; if it uses "six months," count by the calendar.
Forgetting the end-of-month rule. August 31 plus six months is February 28 or 29, not a calendar-overflow date. Some software libraries do not clamp automatically and silently roll the result into March.
Misreading the passport rule. The six months runs from the entry date, not the return date. A short trip with a passport that expires four months later still fails the rule for most six-month-validity countries.
Counting from the wrong end. "Six months ago" excludes today by convention. Six months before May 13 is November 13, not November 12, in the corresponding-day convention used by most US courts.