Months to Days

A Month's Notice and Thirty Days' Notice Are Not the Same Clause

Notice is the one part of a tenancy that both sides read carefully, usually on the evening it has to be served. The clause says one month, or two months, or thirty days, and the question underneath it is always the same: what date does the letter have to be dated, and what date does the tenancy actually end? Those are two different questions, and the difference between a month expressed as a corresponding calendar date and a month expressed as a fixed count of days is where deposits get argued over.

Conversion factor: this converter's month is a fixed 30.436875 days — one twelfth of a 365.2425-day mean year — so multiply months by 30.436875. Two months reads 60.87 d and three months reads 91.31 d. Those are averages for planning; a real two-month gap between corresponding dates is anywhere from 59 to 62 days.

The Three Ways a Clause Can Be Read

The corresponding-date reading

"One month" runs from a date to the same date in the following month. Serve on the 14th and it expires on the 13th or 14th of the next month, however many days that month happens to hold.

The fixed-day reading

"Thirty days' notice", the common wording in month-to-month agreements across much of the United States, is exactly thirty days counted forward. February and July give identical answers.

The whole-rental-period reading

Some periodic tenancies require notice to expire at the end of a period, so a letter sent mid-month does not start counting until the next rent day. In practice that can mean almost two months of rent.

Local law can override all three

Statutory minimum notice, prescribed forms and service rules differ by jurisdiction and frequently beat whatever the agreement says. The clause is the starting point, not the final word.

Checking a Notice Length Before the Letter Goes Out

The converter gives you the size of the period. The calendar gives you the date. Doing both, in that order, is what stops a notice being served a week too late.

Enter the notice length the clause states

Type 1, 2 or 3 into the left field and read the day figure beside it. Halves work too — 1.5 months comes out at 45.66 days — and a comma is accepted in place of the decimal point.

Count the same period on a real calendar

Mark the corresponding date in the target month and count the days between. If your count is materially below the converted figure — a January-to-March two-month gap is 59 days against 60.87 — you are in the short half of the range and should not be cutting it fine.

Read the clause wording, not the heading

"One month" and "30 days" behave differently in February, and "not less than two months ending on the last day of a period" is a third thing again. Whichever it is, add the time your method of service is deemed to take.

Swap when a statute quotes days

The swap button (↔) turns the page into d → mo, which is what you want when a rule is written as 90 days and the tenancy talks in months: 90 days is 2.96 months, so it is fractionally short of a full quarter.

Never serve a notice on an average: the 30.436875-day month here is a smoothed figure for comparing periods, not a legal date calculation. Calendar months run 28 to 31 days, service rules add their own time, and this page is general information rather than advice on your tenancy — count the actual dates, and check the statutory minimum for your jurisdiction.

Notice Clauses and the Days Behind Them

Each common notice length, the flat figure this converter returns, and the spread you get counting real calendar dates instead. The last column is the range between the shortest and longest possible run of months.

Clause	Months (30.436875 d)	Days	Real calendar span
Fourteen days for rent arrears	0.46 mo	14 d	14 d, fixed
One month's notice	1 mo	30.44 d	28–31 d
Thirty days' notice	0.99 mo	30 d	30 d, fixed in every month
Two months' notice	2 mo	60.87 d	59–62 d
A quarter's notice	3 mo	91.31 d	89–92 d
Six-month break clause	6 mo	182.62 d	181–184 d
Twelve-month fixed term	12 mo	365.24 d	365 or 366 d

The pattern worth remembering is that "one month" and "30 days" are only equal in a 30-day month, and they diverge in opposite directions either side of it: a January notice under a one-month clause gives the tenant 31 days, while the same clause served in February gives 28. Over two months the spread reaches three days and over six it is three again, always in the same direction: periods that run through the winter half of the year are the short ones — small numbers that stop being small when a deposit deduction or a possession date turns on them.

What This Pair Does Around a Tenancy File

Size up a clause while you read it

Both fields update as you type, so a notice period written in months turns into a day count you can hold against a diary without opening anything else.

Compare a statutory day figure with a contractual month

Reversing the pair puts a rule expressed in days on the same footing as a clause expressed in months, which is how you find out which of the two is actually longer.

Weeks for a weekly tenancy

Both dropdowns search every time unit, so a weekly periodic tenancy or a fortnightly rent cycle converts on the same page as a monthly one.

A plain number for the proration sheet

The copy control returns the digits alone, with no unit attached, ready for the spreadsheet cell where a part-month rent calculation lives. Ctrl + C in a field does the same.

Notice Questions Landlords and Tenants Argue Over

Does "one month's notice" mean thirty days?

Usually not. Where an agreement says "one month", the ordinary reading is a calendar month running to the corresponding date in the next month — serve on 14 February and it expires around 14 March, which is 28 days, while the same clause served on 14 July gives 31. Where the agreement says "30 days", the count is fixed and the calendar is irrelevant. The two wordings coexist because different jurisdictions grew different habits, so read the words in your own agreement rather than assuming the two are interchangeable.

What happens if I serve notice on the 31st and the next month is shorter?

There is no 31 February, so the corresponding-date rule falls back to the last day of the shorter month. A month from 31 January lands on 28 February, or 29 in a leap year — 28 or 29 days, the shortest month's notice anyone ever gets. The same applies to 31 March into April, and to 29, 30 and 31 running into February. If the timing matters, serve a day or two earlier and remove the argument entirely; a notice that is longer than required is almost never a problem, while one that is a day short can be invalid.

Does notice have to end on a rent day?

Under many periodic tenancies, yes — the notice must expire at the end of a rental period rather than at some arbitrary point inside one. The practical effect is severe: on a tenancy running from the 1st, a letter posted on the 3rd cannot expire on the 3rd of the following month, so the period does not begin until the 1st and the tenant pays almost two months. Other regimes have abolished that requirement and let notice run from the date it is given. Establish which applies before deciding when to post, because it is worth more than any arithmetic on this page.

How is rent prorated for a part month at the end of a tenancy?

Three methods circulate and they give different answers. Take a rent of 1,200 a month with 9 days occupied in a 31-day month. Dividing by the days in that actual month gives 38.71 a day and 348.39 owed. Annualising instead — twelve months of 1,200 is 14,400, divided by 365 — gives 39.45 a day and 355.07. A flat 30-day convention gives 40 a day and 360. The spread here is under twelve units on a small balance, but the same three methods applied to a large deduction produce a dispute, so agree which one the tenancy uses before anyone starts calculating.

Can I rely on the 30.44-day figure when I serve a notice?

Use it to compare periods, never to fix a date. The figure exists because a converter has to give a month one definite length, and the mean of 30.436875 days is the least misleading choice — it is the Gregorian year shared out evenly, so twelve of them come to exactly 365.2425 days with no drift. What it cannot do is tell you which side of that average your particular months fall on. A notice period is counted on a calendar, from the date of service under whatever rule governs service, and no average will match every instance of it.