Dilution rates can range from .1% to 5% depending on what oil you’re using and for what purpose. Generally, for daily use, you'll want a lower ratio and for more acute situations a higher ratio is used.
This dilution chart from the Tisserand Institute shows how much variation can exist when it comes to using essential oils. Hence the line between science and art.
Just remember, you can always add more oil to your blend, but you can’t take it out. So start out with less and add more as you go.
Generally, a safe dilution for most aromatherapy and personal care applications is 2%. A maximum 1% dilution should be used on children, pregnant women, and elderly persons.