Months From Today Calculator

Months are the messiest unit in calendar math, because they are not all the same length. This calculator uses the same rule contracts and banks use, so the answer matches what you would get from a lawyer or a billing system.

The month-end problem, and how this handles it

Adding a month usually means keeping the same day number and moving to the next month. March 15 plus one month is April 15. Simple enough until the day number does not exist in the target month.

January 31 plus one month is the classic case. February has no 31st. The convention almost everywhere, including in most legal and financial contexts, is to clamp to the last valid day, so you get February 28 or February 29 depending on the year. This calculator follows that rule.

The rounding is worth knowing about because it is not reversible. January 31 plus one month gives February 28, but February 28 minus one month gives January 28, not January 31. That is expected behaviour, not a bug, and it is how contracts are read too.

Where the month count actually matters

Leases and rental agreements are written in months almost without exception. A six-month lease starting on the 31st has a real end date, and that date is worth knowing before you sign.

Subscription billing works the same way. Anyone who has been charged on the 28th instead of the 30th has met the month-end rule without realising it.

Warranty periods, probation periods, and visa durations all get quoted in months. So do medical follow-ups, especially anything on a three or six month review cycle.

Loan terms and payment plans are month-based as well, which means the final payment date depends on this same arithmetic.

Frequently asked questions

What happens with January 31 plus one month?

You get February 28, or February 29 in a leap year. When the day number does not exist in the target month, the result clamps to that month's last day. This is the standard convention in contracts and billing systems.

Is 3 months the same as 90 days?

Not usually. Three months from January 1 is April 1, which is 90 days. Three months from March 1 is June 1, which is 92 days. If a contract says 90 days it means 90 days, not three months, and the difference can matter.

How many days are in 6 months?

Between 181 and 184 depending on which months you cross and whether a leap year is involved. There is no fixed answer, which is exactly why calendar-accurate calculation is needed.

Can I go backwards by months?

Yes. Set the operation to subtract to count back from your start date.