The Great Software Estimation Delusion: Why We’re Always Wrong

Ah, software estimation. The fine art of confidently guessing how long something will take, being wrong, and then pretending we’re surprised.

Here’s a wild idea: maybe we suck at estimating software delivery times because software isn’t construction. You can’t just say, “It’s like building a house!” and call it a day. No two codebases are the same. No two features are truly identical. Hell, even the same feature request can morph into a JIRA chimera halfway through development.

Here’s why we consistently screw it up:

1. Unknown Unknowns: The classic. You plan for what you know. Then Bob’s authentication middleware decides today’s the day it explodes. Now you’re spelunking into 2014-era spaghetti code.
2. Changing Requirements: Because nothing says “agile” like pivoting halfway through the sprint and pretending that doesn’t add time.
3. Optimism Bias: Developers are the only people who think “Yeah, this won’t take long” after discovering a 300-line method called processEverything().
4. Parallel Delusion: We plan like everyone works in parallel. Reality? It’s a dependency chain made of duct tape. One person’s blocker is another team’s vacation.
5. Meetings. So. Many. Meetings.: Half your sprint is burned syncing up, aligning, and circling back.
6. Tooling & Tech Debt: Your IDE crashes twice a day. Your CI/CD pipeline is powered by hope. But sure, that estimate was solid.
7. Definition of Done (DoD): What does “done” even mean? Merged? Deployed? Tested? Monitored in production for three days with no errors? Everyone’s got their own secret version of DoD—and they all take different amounts of time. Spoiler: only one of them actually includes the things users care about.

Add all that up, and of course we’re late. Every. Single. Time.

So what’s the fix? Stop pretending you’re a fortune teller. Instead:

• Break work down until it’s laughably small.
• Add buffer time, then double it, then add two more days.
• Plan for change, not perfection.
• Include the real Definition of Done in your estimates: deployed, verified, support docs written, telemetry added, champagne popped.

And stop punishing teams for bad estimates—they’re not failing, they’re just in software.

The truth is, we don’t need perfect estimates. We need realistic ones. We need transparency. We need teams that communicate and adapt when reality doesn’t match the slide deck.

We need to stop treating “done” like it’s a checkbox and start treating it like the finish line it actually is—with all the hurdles, sprints, and faceplants along the way.

And maybe, just maybe, we need to stop pretending that software estimation is anything more than educated guesswork wrapped in Post-Its and prayed over in sprint planning.

Because if we’re going to be wrong anyway, we might as well be wrong with style—and a better process.

So go ahead. Make your estimates. But this time, account for Bob, the CI pipeline, your cat walking across the keyboard, and the team’s mysterious Friday brain fade. And please—define “done” before you start. You’ll still be wrong. But you’ll be wrong smarter.