A commonly cited (if oversimplified) starting rule: subtract your age from 100 to get a rough equity percentage. At 30, that suggests roughly 70% equity; at 50, roughly 50%. It's a reasonable first approximation, not a precise formula — your actual risk appetite, income stability, and how many dependents rely on you all matter too.
What matters more than the exact split is the direction it should move: equity exposure should generally decrease as you approach a goal, not because equity becomes worse, but because you have less time to recover from a downturn right before you need the money. This is why the Goal Planner on this site automatically shifts toward safer instruments for goals under 3-5 years away, regardless of which investor profile you pick.
It's also worth allocating separately per goal rather than treating your entire portfolio as one blob. Money for a goal 25 years away (retirement) can reasonably carry far more equity risk than money for a goal 2 years away (a wedding, a car), even if both goals belong to the same person at the same age. Thinking goal-by-goal, rather than portfolio-by-age alone, usually leads to better-calibrated decisions.