If you leave UK on 8 dec what date will arrive in New Zealand?

To calculate the arrival date in New Zealand, you need to consider the time difference and the fact that you will be crossing the International Date Line (IDL).

The time difference between the UK (GMT) and New Zealand (NZST) is +13 hours. So, if you leave the UK on 8th December, you will arrive in New Zealand on 9th December (assuming a direct flight).

However, since you will be crossing the IDL, you will lose a day when flying from the UK to New Zealand. The IDL is an imaginary line that runs approximately along the 180th meridian. When you cross the IDL from east to west, you "lose" a day.

As you will be flying from west to east (from the UK to New Zealand), you will "gain" a day. Therefore, if you depart from the UK on 8th December, you will arrive in New Zealand on 9th December, not on the 10th December.