Things vary wildly based on your personal situation.
Best thing to do, IMO, is run your situation through FIRECalc.
But, making massive assumptions based on what isn't known, 300k at a 4% SWR is 12k/yr, or 1k per month. If your spending is 1400/mo, you're 400/mo. short. You'd need a stache of 420k (so you'd be 120k short) to support 1400 per month.
(And, of course, all the unknowns I've mentioned, kids, college, healthcare, travel, whatever.)