I disagree with the selected answer. There's no one rule of thumb and certainly not simple ones like "20 cents of every dollar if you're 35".
You've made a good start by making a budget of your expected expenses. If you read the Mr. Money Mustache blogpost titled The Shockingly
Simple Math Behind Early Retirement, you will understand that it is usually a mistake to think of your expenses as a fixed percentage of your income. In most cases, it makes more sense to keep your expenses as low as possible, regardless of your actual income.
In the financial independence community, it is a common principle that one typically needs 25-30 times one's annual spending to have enough money to sustain oneself forever off the investment returns that those savings generate (this is based on the assumption of a 7% average annual return, 4% after inflation). So the real answer to your question is this:
- Calculate your annual expenses, say x
- Multiply by 25 (You can also use 30 instead of 25, if you want to be more conservative)
- Calculate your current annual savings, say y
- 25 * x / y is the number of years, call it z, you will take to save up enough money to retire
Keats brought to my attention that this formula doesn't work that well when the savings rates are low (20% range). This is because it assumes that money you save earns no returns for the entire period that you are saving. This is obviously not true; investment returns should also count toward your 25-times annual spending goal. For that reason, it's probably better to refer to the blog post that I linked to in the answer above for precise calculations. That's where I got the "37 years at 20% savings rate" figure from.
Depending on how large and small x and y are, you could have enough saved up to retire in 7 years (at a 75% savings rate), 17 years (at a 50% savings rate), or 37 years! (at the suggested 20% savings rate for 35-year olds).
As you go through life, your expenses may increase (eg. starting a family, starting a new business, unexpected health event etc) or decrease (kid wins full scholarship to college). So could your income. However, in general, you should negotiate the highest salary possible (if you are salaried), use the 25x rule, and consider your life and career goals to decide how much you want to save. And stop thinking of expenses as a percentage of income.