A maths question...

because I'm being daft.... a group of us are going camping at the end August and I called the site to find out if we were allowed to put two tents on the pitches. The lady said that the pitches weren't very big, 21ft square which I have worked that out to be 6.3m square - is that right? (I'm a metric girl
)
If yes, then it probably will be quite a bit of a squeeze with two tents
but it would save a lot of money if my brother and his family and I can share a pitch as each one is £111 for the three nights.
but just wondering if I got my maths right?

If yes, then it probably will be quite a bit of a squeeze with two tents

but just wondering if I got my maths right?