There are two sorts of first class stamps, the small ones are worth 41p. The big ones, for "large" letters are worth 66p.

Ok...thank you soo much ...

Hi,

The value of a 1st class stamp is 41p. Airmail up to 20grams to elsewhere in Europe is 60p, up to 40gms it is 88p. So, if you want to save money you could affix one 1st class stamp and make up the remainder by using 10p stamps.

To make it easier I would recommend to affix two 1st class stamps, however that means a loss of 22p.

It's up to you and hope that helps

I really need some help with this, so please, if somebody can...
My sister wrote me she bought me some UK 1st Class stamps. She asked for 60 p stamps, however a postman gave her these stamps and I really don´t know what is their value because she wrote me one stamp costs 41 p. However I was lookinh for some informations, but they are so contradictory...
I read that I can use one 1st class stamp for a small letter (to 20 grams) from UK to every country in Europe- so it would be like a one 60 p stamp. However, if I have a bigger and heavier letter, I have to use more of these stamps because then, they have a value 41 p.
So it is true? And possible?
However, thanks for any help..