How AI-Generated Excel Sheets Far Exceeded My Expectations

Excel x AI can be used for work. A 100-task x 26-week project Gantt chart. It moves smoothly when you touch it. This was made instantly with a single prompt. First, watch this 30-second video 👇

Everything moves smoothly when you interact with it.

(There's a note link at the bottom where you can download the Excel file!)

When you change the dropdown in the top left from "Standard Plan" to "Delay Recovery," thousands of cells are repainted at once, bars shift to the right, costs increase by 190 million yen, and the staffing graph grows. If you advance "Today" by one week, delayed tasks turn red.

This isn't just a table anymore.

It supports decision-making from various angles.

By the way, there are no macros or VBA. It was made with just one prompt.

Why can this be drawn with just formulas?

The mechanism is simple. Each square in the Gantt chart isn't a shape; it's just a cell. It contains a formula that determines "Is this date within the task period?" and conditional formatting just paints the color.

In other words, the bars aren't drawn; they are calculated.

So, if you switch scenarios, thousands of cells are recalculated, and the picture redraws itself. This is why macros aren't needed.

Prompt you can use by just copying and pasting

This is the actual prompt I used. It works as is in any environment that can generate Excel files, like ChatGPT or Claude (I ran it in Claude Code).

1# Task
2Build an "Integrated Project Board" in a single Excel file.
3Do not use macros or VBA; use only formulas and conditional formatting.
4Success is defined as the entire board redrawing when scenarios are switched.
5
6## Premises (Replace this with your own project)
7- Project: Core System Renewal (ERP Implementation) *Example: New factory launch / Product launch
8- Period: 26 weeks (182 days) *Can be 12 or 52 weeks
9- Teams: PMO / Business / Development / Data Migration / Infrastructure / Education *Your departments
10- Scenarios: Standard Plan / Delay Recovery / Accelerated *Plans you want to compare
11- Tasks: Automatically generate about 100 tasks assigned to the teams above *Paste real tasks if you have them
12
13## Sheets to Create
141. Project Gantt (Main): 1 row per task x daily grid. Color-coded by team, shading for completed/remaining, ◆ milestones, red vertical line for reference date.
152. Task Data: Start date, duration, personnel, and progress for each scenario.
163. Resource Loading: Heatmap aggregating daily concurrent personnel.
174. Cost Summary: Team unit price x man-days compared by scenario.
185. Delay/Risk: "Delay" judgment if actual is 10pt behind plan, auto-extract Top 10.
196. Sensitivity Analysis: Matrix showing how completion date moves with staffing rate x duration compression rate.
20
21## Operation Mechanism (The key part)
22- 3 dropdowns at the top of the Gantt: Scenario / Team Filter / Reference Week.
23- Changing any of these updates bars, KPIs, charts, and delay judgments via formulas.
24- Gantt bars are drawn using cell formulas + conditional formatting (no shapes or images).
25
26## Constraints
27- No macros, VBA, or external add-ins. Formulas only.
28- KPI cards in the header: Working days / Total man-hours / Total cost / Peak staffing / Progress / Number of delays.
29- Sample data is fine, but numbers must link consistently.
30- Finally, recalculate all formulas and confirm zero errors before delivery.
31
32## Output
33- One .xlsx file (ready to work when dropdowns are touched).

When you want to make it for other tasks

This prompt looks specific to project schedules, but it actually works for other tasks if you just swap the content. You only need to touch the 5 lines under "## Premises."

For a new factory launch, set the period to 52 weeks and teams to Equipment / Production Tech / QA / Hiring.

For a new product launch, 20 weeks with Product Dev / Marketing / Sales / SCM. For a hiring plan, 26 weeks with HR / each department.

Just replace the scenarios with plans you want to compare, like "Standard / Reduced Applicants / Increased Agency Support."

You don't need to touch anything below "## Sheets to Create."

That part describes how to build the Excel sheet, so it works even if the theme changes.

3 tips for successful generation

**1. Explicitly state "No macros"

**If you don't, it will try to use VBA. Macro-enabled files trigger warnings when shared, and people won't open them. By restricting it to "formulas and conditional formatting only," the AI starts getting creative with conditional formatting instead.

**2. Provide the success condition in one sentence

**"Success is defined as the entire board redrawing when scenarios are switched." Whether this sentence exists or not makes a world of difference. Write how it should look when you "win," not just what to make. This is the most effective tip.

**3. Write "Recalculate and check for zero errors" at the end

**Without this, formulas might be delivered broken. You can include the inspection process in just one line.

Applying the same logic to other tasks

The interesting part isn't the Gantt chart itself, but the framework where everything is redrawn when premises change.

So, using the same framework, I tried it for completely different tasks.

**24-Hour Shift Board

**A shift table for 42 people x 28 days. When you switch the scenario to "Peak Season (1.4x volume)," days with labor shortages turn red, and violations of the 6-day work limit or rest intervals are automatically flagged. The task of staring at a shift table to find legal violations becomes just looking at colors.

**Equipment Loss & Improvement Effect Board

**15 machines x 3 shifts x 42 days color-coded by loss type. Switching the scenario to "Enhanced Preventive Maintenance" turns the bars green, OEE rises from 64.0% to 72.9%, and an annual effect of "73.41 million yen" is calculated. The numbers needed for an improvement proposal are all gathered on this one sheet.

Conclusion

Excel has changed from something you "make" to something you "have AI make." Our remaining job is just to determine the direction and see what success looks like.

For more, please check the note.

• Two prompts for the shift board and equipment loss board
• Excel data for the three tables (I want you to touch and move them)

Check it out here ↓↓

https://note.com/uchita_success/n/n693b5dd68246

Thank you for reading to the end.