This line jumped out at me: “Anyone who’s ever guesstimated the cost of anything knows to tack on an extra 15% for caution”. Struck me as amusing given that conservative estimating in software uses a factor of Pi, not 1.15.
I thought the rule of thumb is “double the number and switch to the next bigger unit of time”. 2 hours –> 4 days, 5 days –> 10 weeks, 3 weeks –> 6 months, etc. This is accurate surprisingly often. ;)
That’s one I’ve heard, another is “square it and then multiply by 3/multiply by Pi”. The lowest estimate method I know of is simply multiplying by Pi, which is why it was amusing to read civil engineers casually mentioning they add just 15%.
