It doesn't matter. If you earned $500k we would facepunch you for saving "only" $250k. If you earned $20k we would say you are doing well saving $10k.
I get irritated with %'s, because of the way they can mislead. Starting from a high base, low base etc etc. Dollar values make more sense.
Save as much as you can and spend as less as you can.
If you really feel the need to calculate a %, then I suggest you include all income less tax in your denominator, and for the numerator use (denominator minus expenses).
Pretax retirement contributions are not expenses, mortgage interest is an expense, mortgage principle is not. $4k to spend on renovating the house is capex, not an expense. Meaning you have swapped cash for an asset and you are no better or worse off, unless the house has gone up in value by more than the $4k.
You would hope it doesn't go down in value because you chose granny's wallpaper from the 1930's that nobody finds attractive anymore :)