A year and a half is 18 months. One year has 12 months and half a year has 6 months, so 12 + 6 = 18. In other units, a year and a half is about 78 weeks or 547 to 548 days.
| Time | Months | Weeks (approx.) | Days (approx.) |
|---|---|---|---|
| Half a year | 6 | 26 | 182 to 183 |
| 1 year | 12 | 52 | 365 (366 in a leap year) |
| 1.5 years (a year and a half) | 18 | 78 | 547 to 548 |
| 2 years | 24 | 104 | 730 to 731 |
| 2.5 years | 30 | 130 | 912 to 913 |
How to work it out
Multiply the number of years by 12, because every year has 12 months.
- 1.5 years × 12 = 18 months
- 2.5 years × 12 = 30 months
- 0.5 years × 12 = 6 months
To go the other way, divide months by 12: 18 months ÷ 12 = 1.5 years. So “18 months old” and “a year and a half old” mean the same age.
Quick years and months converter
How long is half a year?
Half a year is 6 months. In days it is 182.5 days on average, or 183 days in a leap year. The exact number depends on which months you count: January to June has 181 days (182 in a leap year), while July to December has 184 days.
Is 6 months half a year?
Yes. A year has 12 months, so 6 months is exactly half of it. That is why a meio aniversário falls six months after your birthday, on the same day of the month.
A year and a half in other units
| Unit | A year and a half |
|---|---|
| Months | 18 |
| Weeks | about 78 |
| Days | about 547.5 (547 or 548, depending on leap years) |
| Hours | about 13,140 |
| Seasons | 6 |
| Quarters | 6 |
Common examples
- A baby who is a year and a half is 18 months old. Many parents switch from counting in months to years around age 2.
- An 18-month contract or lease runs for a year and a half. One starting 1 January 2027 ends on 30 June 2028.
- A year and a half from today: add 1 year and 6 months to the date. From 2 November 2026, that is 2 May 2028.
- Half birthdays: a child who turns 1 in March is a year and a half old in September. Find any date with the calculadora de meio aniversário.
Months to years chart
| Months | Years |
|---|---|
| 6 months | 0.5 years (half a year) |
| 9 months | 0.75 years |
| 12 months | 1 year |
| 15 months | 1.25 years |
| 18 months | 1.5 years (a year and a half) |
| 21 months | 1.75 years |
| 24 months | 2 years |
| 30 months | 2.5 years |
| 36 months | 3 years |
Year and a half questions
How many months are in a year and a half?
There are 18 months in a year and a half: 12 months plus 6 months.
How many weeks is a year and a half?
About 78 weeks. A year has about 52.18 weeks, so 1.5 years is about 78.3 weeks.
How many days is a year and a half?
About 547 or 548 days, depending on whether the period includes a leap day.
Is 18 months a year and a half?
Yes. 18 months ÷ 12 = 1.5 years.
How many months is half a year?
Half a year is 6 months, or about 182 to 183 days.
Related guides
- Half birthday calculator: find the date six months after any birthday
- Half birthday meaning
- What year will it be in 4 years?
Last updated: 2 November 2026. Weeks and days use an average year of 365.25 days.