My wife got a hybrid role offer. Good job, real company, worth taking seriously. And almost immediately the conversation turned into: okay, but how do we actually compare this to what she’s doing now?

She’s remote. The new role is three days a week in office. Everyone acts like that’s a minor detail. It’s not.

The instinct is to think about gas. $80 a month, whatever, you factor it in and move on. But that’s not the cost. That’s the part of the cost you can see, and it’s also the smallest part.

The number you’re not thinking about

Here’s the thing about fuel costs: they feel real because you’re physically pumping gas. But run the math on 25 miles each way, three days a week, and you’re at about $950 a year. Yeah. Less than a grand.

The IRS mileage rate — $0.67 a mile, which folds in depreciation, maintenance, insurance, all of it — gets you closer to $4,500. That’s a more honest number. Still not the one that matters.

Your time matters.

At $110k, you’re making about $53 an hour. A 45-minute commute each way, three days a week, is 202 hours a year you’re not getting back. That’s $10,700. Not in gas. Not in wear on the car. In hours.

More than double the vehicle cost. Most people walk into a salary negotiation thinking about $950. They should be walking in thinking about $15,200.

The gross-up problem

Even $15,200 isn’t the right number to use at the table, because salary is pre-tax and commute costs come out of the other side.

You need to gross it up. Figure out how much pre-tax salary you’d actually need to earn to cover what the commute takes from you post-tax.

At a combined marginal rate around 28% — federal plus Colorado — that $15,200 in real post-tax cost turns into $21,100 in required pre-tax salary. That’s what the commute actually costs you in offer terms.

So the hybrid offer at $110k is equivalent to a remote job paying $88,900.

If the remote option is sitting there at $100k, the $110k hybrid isn’t $10k better. It’s $11,100 worse. You’d need them at $121k before you’re genuinely ahead.

That’s not a rounding error you shrug off. That’s a whole different answer to the question “is this offer worth it.”

So I asked Claude to build it

Doing this math by hand every time you tweak a variable is stupid. Change the days per week, adjust the salary, swap in a different commute distance — you’re redoing everything from scratch.

I described the problem to Claude. The inputs, the two modes (IRS rate versus actual fuel cost and MPG), the time cost calculation, 2025 federal tax brackets for the gross-up, hybrid days dialed in separately from total work weeks. It built a full-stack FastAPI backend and React frontend in a day.

This is the self-hosted AI stack doing actual work on an actual problem. Not a proof of concept. The calculator handles commute distance, days per week, salary, parking costs. Shows you the pay period breakdown — exactly how much more per paycheck you’d need. Has an e-bike ROI panel that tells you break-even in months if you can bike part of the route. Metric and imperial toggles.

We used it. That’s the whole point.

What the numbers said

Here’s what the calculator spits out for the scenario above — 25 miles each way, 3 days per week, $110k, 45-minute commute:

  Annual cost
Vehicle cost (IRS rate) $4,500
Time cost $10,700
Total commute cost $15,200
Gross-up to pre-tax (28%) $21,100
Equivalent remote salary $88,900

The offer letter says $110k. The number you’re negotiating from is $88,900.

Your numbers will be different. Shorter commute, two days a week, higher salary — the calculator takes all of it. The point isn’t the specific output. It’s that you run it before you walk in, not after.

The calculator doesn’t decide anything. It just makes sure you’re not negotiating against a number you made up in your head.

The repo is at github.com/mosburn/commute-calculator. Clone it, run make install && make run, put in your actual situation. Do it before you negotiate.