I calculated mine in weekly take-home pay. I accounted savings as mortgage payments (since I make a lot more than my minimum mortgage payment a week), RRSPs, and my two savings accounts for vacations and house repairs. I suppose the vacation account isn't a true 'savings' account, in the MMM sense though, since we do drain it periodically, for trips, and things like Christmas gifts for family members. But, on it's face value, I have a savings rate of 37% a week. The remainder, which I didn't add in, goes to insurance (house and vehicle), food, utilities, property tax, DH's beer and wine-making supplies and a few monthly payments towards DH's student loan.
I have two different thought processes for this:
1) Savings should be anything that you are removing from your chequing account that isn't being spent (such as debt repayments, RRSPs, investments etc).
2) Savings should be anything that, at the end of the year, increases your net worth. I could calculate this, but in 2012, we paid for things that weren't luxuries, but still didn't increase our net worth, such as about $20,000 out of my health care spending account (self-funded through my business). In that grain though, I'd have to somehow figure out what the increase in value of my house, because of the renovations we did last year. That would be tricky.