SEP IRA contribution limit

I tried to set up my SEP IRA contribution for my wife's 1099 income.   All the information I found find by googling says 25% of net income (i.e. after cost and self employment tax deducted). The remaining net income (after removing all business cost) is about $32K.  Removing self employment tax by multiplying it with 92.35%.  That's about $29.5K.   25% of it is close to $7.5K.  But Turbo only calculated $5.5K, although I selected "maximize it".   Why?

 

Thanks