it's hard to get a scale with my allowance
Right. Just for the record (since others may read this), SN is about 2g per ml.
So a rounded (not "levelled off") tablespoon, of around 15ml, will be about 30g of SN.
The heaped / levelled distinction is slightly confusing. Going to recheck some facts on that aspect of things; 17-18 g is also in a tablespoon, as stated by others.
But in general, a tablespoon is considered to be around 15ml, which will be about 30g of SN.