Save Time with AI: Level up Excel skills with ChatGPT

Productivity & Problem-Solving
Written By Darren Mitchell

Not every AI project has to be flashy. Sometimes, it's about fixing something quietly but effectively.

A friend in HR reached out, overwhelmed by the complexity of tracking Paid Time Off (PTO) across employees with different titles, tenures, and promotion dates. They were doing it manually in Excel, and it was starting to break.

I offered to help—and brought ChatGPT along for the ride.

The Challenge

We needed to build a single formula that could:

  • Calculate total PTO days based on an employee’s role and time at the company

  • Account for mid-year changes in PTO (due to tenure milestones or promotions)

  • Be used in Excel, without needing any external tools

  • Keep the data private (no uploading spreadsheets)

The Process (with ChatGPT as Co-Pilot)

Step 1: Build the First Formula

I described the rules and assigned each factor to specific cells (e.g., hire date in A2, title in B2). ChatGPT generated a formula based on my explanation.

Step 2: Refine the Logic

I asked it to walk me through its own logic—then tweaked the rules. We adjusted the math to fix edge cases, like how to handle someone promoted in July.

Step 3: Modularize the Beast

Eventually, the formula got too long for one cell. So I asked ChatGPT to split it into multiple supporting formulas, each doing one job (e.g., prorating PTO, calculating months of tenure, adjusting for promotion).

Step 4: Final Assembly

With sub-formulas hidden in helper columns, I built a final column that delivered clean PTO totals, dynamically updated based on any inputs.

The Outcome

  • No more manual PTO math

  • Fully customizable for different departments or policy changes

  • No data sharing required—just smart formula logic

  • One happy HR partner

Why This Matters

This project wasn’t about building a product or launching a campaign. It was about solving a real problem with clear thinking and the right prompts.

It also showed me how powerful AI can be for non-technical users—when used intentionally. You don’t need to be a developer. You just need to know how to describe your problem and ask the right follow-ups.

If you’re drowning in spreadsheets or trying to automate the parts of work that drain your time, AI can help. You just have to start.

Darren Mitchell
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