It was 2 a.m. and I should’ve been asleep. Instead, I was lying in bed doing back-of-the-napkin calculations about whether Andy Dufresne could actually dig through that wall in 19 years with a tiny rock hammer. This is what happens when you spend years doing maths and still can’t turn off your brain at night.

This kicks off something new I’m trying: The Monthly Rabbit Hole. Every month I fall into one idea, a calculation, a book, a stray sentence, and write it up small. One month, one rabbit hole. This month’s started with a prison movie.

Turns out, the math checks out beautifully. And it taught me something I keep forgetting.

Let me walk you through it. The tunnel looked roughly 10 meters long and half a meter wide based on Andy’s shoulder width. Assuming a circular cross-section, that’s a volume of about 1.96 cubic meters. With a density of roughly 1,600 kg per cubic meter for concrete and sand, we’re talking about 3,136 kg of material to remove.

Nineteen years is 6,935 days. If Andy scraped out between half a liter and one liter per day, he’d remove about 5.2 cubic meters in that time. He only needed 1.96. The guy could’ve skipped every other day and still made it.

Over 19 years he could remove about 5.2 m³ but needed only 1.96. Barely 38% of his capacity.

Here’s what hit me: the dreams you think will take 600 years are hardly 20 years away. That’s a 30x gap. Even if real life isn’t a movie and the factor is only 5x or 3x, the thing you’re certain will take a decade? It might take three and a half years. My master’s advisor said something similar when I started: small extra effort every day compounds brutally over 150 to 200 weeks.

I wrote something on a sticky note a while back that still holds up: tiny steps taken consistently over a long period of time result in magic. The Shawshank math proves it.

So the next time you file a dream under “someday,” run the actual numbers first. The wall is usually thinner than the sentence makes it sound.