Consistently saving a small percentage of your salary is a simple way to ensure you’re prepared for retirement.

As a rule of thumb, most financial advisors suggest you save 10% to 15% of your earnings.

Here’s a case study assuming you start with no savings, plan to retire at 65 and have investments that earn 6% annually.

If you want to retire with $1 million, you’ll need to invest about 9% of a salary of $70,000 starting in your 20s. Waiting until you’re older will require a larger portion of your pay. If you wait until your 40s, then that number jumps to 25% of your salary. This does not account for variables such as a possible pay increase or decrease, employer match, inflation or any other of life’s curveballs.

Watch this video to find out how much money you will need to invest to save $1 million for retirement, broken down by age.