I know it's a dumb trick but it works for me: I use the Fibonacci sequence. 3 miles? 5 km. 8miles? 13km. 33 miles? 55km.

My dumber version: Just multiply by 1.5. It's fine unless you are using a treasure map.

Same here. Usually it's x1.6 but 1.5 is easier to calculate and you add a teeny bit after.

	▲	alt227 12 hours ago \| parent [-]
		Mine is divide by 3, multiply by 5. Simple and quite accurate.

catoc 18 hours ago | parent | prev | next [-]

Ha! That’s nice.

I never realized 1.609 miles/km is close to the golden ratio (1.618)

	▲	donpott 16 hours ago \| parent [-]
		It is quite clever. My own rule of thumb is "add half of the amount in miles, then 10% of the (original) amount in miles". What's interesting is that it happens to be just as precise as the method shown above (ie. 1.6 v 1.609 v 1.618 )

mnaimd 14 hours ago | parent | prev [-]

Hey, this is very smart. The golden ratio... Wow!