Every single person is going to answer this differently. I only know because it comes up a lot.
My answer: Use standard accounting!
(income - expense) / income
It's that easy! If you want percent, multiply by 100.
Now: You need to identify what is income and expense. I *always* used gross. If my employer put 3% into my 401k.. that's income. If money came out of my check for FICA or federal taxes, that's an expense.
Your problem is going to be the "spending: no clue". If you don't know your expenses, you don't know your savings rate, IMO. There are other really good reasons for tracking expenses. You can see things like "wow, my car is really expensive" or "you know, over the last 5 years, our grocery bill has increased a lot faster than the rate of inflation... what are we doing?"
Also: computers are handy. If you get 4 "good, but different answers" on how to compute savings rates... it's very simple to have the same sets of numbers spit out all 4 rates. Use something automated (or minimally a spreadsheet) and keep track of it over time.
Edit to add:
If I am to assume "money my wife and I saved" and "contributed by employers" is for the last year. And this is the sum total of what you have saved... That would put your expenses at: 150000-64750=85250
By my formula, that's 43% savings.
Now... you may have more or less expenses if you start really categorizing. For example, some portion of a house payment is expense (interest, insurance, taxes) and some part of a house payment is a reduction in liability (principle). If you put $700 into principle this month, sell your house next month, the check coming to you is presumably $700 bigger than if you sold it this month (all other things being equal). Probably overly semantics here but: It's not so much that the "principle is savings"... it's that the principle is an asset transfer from one asset (your checking account) to another (your home equity). But, in essence, you did retain that much of your assets, i.e. "saved" it.
I'll go the other way: You also might have expenses you are not counting. You may have a car you bought last year for $30,000. If you were to sell it this year, it might only sell for $25,000. That $5000 is a real expense. (You could take a $30k expense every 10 years... but that does not make your expenses very predictable and it is hard to really see over time the annual cost of the car.) Personally, I ding myself once a year for the depreciation expense... This gives me a better idea how expensive my car ownership is.
