how much baking powder to change plain flour to SR?

[PeachyClair]

Title says it all really LOL!

Making the gorgeous storecupboard chocolate orange cake (nigella) but run out of SR flour, and can't be arsed to drive 7 miles for a bag just to make the PTA people happy.

Ta anyone

one level tsp per 100g of flour

Message withdrawn

Cd is right - used to do it all the time as in Switzerland they don't do self raising flour. Also using part cornflour for plain lightens the mix.

Thank you