Category: Optimization

Operations research in practice — vehicle routing, staff and shift scheduling, project scheduling and resource leveling, and the free optimization tools I built out of twenty years of Excel models. How the math actually works, and where it breaks.

Retirement Withdrawal Tax Calculator: Your Real Rate

“How much tax will I pay if I take $30,000 out of my IRA?” sounds like it should have a one-line answer. It doesn’t. The withdrawal stacks on top of your other income, it can drag your Social Security into tax with it, and before 59½ there’s a penalty on top. I built a retirement withdrawal tax calculator to do that arithmetic properly for one year, and to show the number most people never see: what the next dollar costs.

It’s free, no signup, and it uses the 2026 federal brackets. I’m 58, single, retired early, and planning my own drawdown, so I use it too.

Retirement withdrawal tax calculator showing $3,226 of federal tax on a $30,000 IRA withdrawal for a single filer with Social Security, a 12% bracket and $222 of tax on the next $1,000
The example below: a 12% bracket, a 10.8% average rate, and $222 of tax on the next $1,000.
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IRMAA Calculator: What One Dollar Over the Line Costs

I’m 58, single, and Medicare is still seven years away. It already matters to me, though, because of one rule: the premium I’ll pay at 65 is set by the income on the tax return I file for the year I turn 63. Those are exactly the years I’d want to do Roth conversions. So I built a small IRMAA calculator that answers the narrow question first: given a year’s income, which Medicare surcharge tier does it land in, what does that cost, and how close is the next cliff?

It’s free, there’s no signup, and it runs in your browser. You enter three things and it answers right away.

IRMAA calculator showing a single filer with $140,000 of MAGI in tier 2 of 5: $2,885 a year extra, $240.40 a month, $31,000 of room before the next step
The example below: a single filer with $140,000 of MAGI lands in tier 2 of 5.
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A Roth vs Traditional 401k Calculator for Your Whole Career

I built a Roth conversion optimizer because retirement is the phase I’m in. That sounds reasonable until you notice what it leaves out: by the time anyone needs a conversion plan, the big decision (traditional or Roth, every paycheck, for decades) has already been made. So I built the piece I was missing: a Roth vs traditional 401k calculator that optimizes the working years and the retirement years together, as one plan.

It’s free and needs no signup. You enter your salary, when you plan to stop working, what you spend, which accounts you have, and how your employer matches. It tells you how much to put in each account this year, and every year after that.

Roth vs traditional 401k calculator results: this year's split between Roth 401(k) and Roth IRA, and the optimal mix compared with always-traditional and always-Roth
The sample plan: this year’s split, and what the optimal mix is worth against the two defaults.
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How to Make an Employee Schedule in Google Sheets

If you search how to make an employee schedule in Google Sheets, you’ll find a hundred templates: names down the side, dates across the top, colored cells. That works fine for a small team on weekdays. It falls apart the moment you run 24/7, with nights, rest rules and people who can’t work certain days. Now you’re counting cells by hand at 11 PM. So I built a free Google Sheets add-on, Shift Optimizer, that fills the schedule for you with a real optimization solver, right inside your sheet.

Below: the manual way first (it’s worth knowing, and for some teams it’s all you need), then the add-on, how I built it, how it’s going so far, and what’s next.

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AI Staff Scheduling in Claude: A Free Solver Connector

Most “AI staff scheduling” tools I tried do one of two things: they let a chatbot write a schedule that looks right and quietly breaks your rules, or they put a little AI button on top of a calendar you still fill in by hand. I wanted the opposite: you describe your team to an AI assistant in plain words, and a real optimization solver builds the roster, with the rules treated as rules. So I built a free connector for Claude that does exactly that. It’s called Shift Scheduler, there’s no signup, and it has been in the Claude directory since late September.

This post covers how to use it, how I built it (and what I broke along the way), what the first month of use looks like, and what I’m changing next.

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