If anyone says it will take a day, it actually means a month.
1week means 1month
1month means 3months
3months means 1year (will take some for the BA and Product Manager to realise actual the problem they are trying to solve)
1year means you won't be working on project, they'll outsource it.

The correct formula is:
Two times the amount using next higher unit.

5 minutes => 10 hours
1 hour => 2 days
1 day => 2 weeks
1 week => 2 months
1 month => 2 quarters
1 quarter => 2 half years = 1 year
1 half a year => 2 years
1 year => 2 decades
1 decade => your heir's heir might finish it...

Also: Software isn't finished. It is abandoned.

@Oktokolo don't neglect fortnight

@electrineer
The formula is for the average dev. Epic devs can be way faster - or slower - dpending on the circumstances...

@Oktokolo I guess the circumstances could include a hot rod near the ass 🤔

@iiii
Traditionally, oversportive cars where indeed huge factors both in slowing devs down and speeding them up.
But nowadays, cars seem to have lost a lot of their emotional and social status potentials. Other "gatgets" took their place...

Yes, think of an estimate then multiply by pi.

For a safe measure, add sqrt of that estimate.