# Get up to speed on an inherited workbook before you let AI change it

> Work on a copy, inspect connections and named ranges, trace backwards from the outputs you need, and only then ask Copilot to describe what a sheet does.

- **Category:** [Excel](https://stepgleam.com/categories/excel)
- **Difficulty:** Beginner
- **Time:** ~45 minutes
- **Tools:** Excel (Microsoft 365), Copilot in Excel
- **Reliability score:** 80/100
- **Steps:** 6
- **Last updated:** 2026-10-26
- **Published:** 2026-10-26

## Tools used

- [Excel (Microsoft 365)](https://support.microsoft.com/en-us/excel) — Formula auditing tools and Inspect Workbook
- [Copilot in Excel](https://support.microsoft.com/en-us/excel/copilot/get-started-with-copilot-in-excel) — Describes what a sheet is trying to do

## What you'll get

A copy of the workbook with your own notes on how the sheets connect, checked against the actual formulas.

## Who this is for

Anyone handed a big workbook with no documentation.

## Before you start

When someone on r/excel asked how to learn a large workbook they had been handed, the answers were consistent: copy it, ask the author if you can, inspect what is connected, and trace backwards from the outputs. A later thread adds that Copilot can describe what a sheet is trying to do. This guide puts those in order.

## Steps

### Step 1: Make a copy and ask the author for a walkthrough

**Tool:** Excel (Microsoft 365)

Work on a copy: *"I'd first make a copy and work on that one in case you mess something up."* If the person who built it is reachable, ask for a walkthrough; the top reply says to phone the creator, or whoever sent it or uses it most.

[Open step 1](https://stepgleam.com/guides/get-up-to-speed-on-an-inherited-excel-workbook#step-1)

### Step 2: Inspect what is connected

**Tool:** Excel (Microsoft 365)

Use the **Inspect Workbook** features for an overall picture, then *"Look for evidence of VBA, data connections / Power Query, and named ranges."*

**Why this works:** Hidden queries and macros change numbers without any formula showing it.

[Open step 2](https://stepgleam.com/guides/get-up-to-speed-on-an-inherited-excel-workbook#step-2)

### Step 3: Find every formula cell at once

**Tool:** Excel (Microsoft 365)

Go to **Home → Find & Select → Go to Special → Formulas** to highlight every formula cell. **Ctrl+`** switches to formula view, though one user warns it can make Excel *"grumpy"*.

[Open step 3](https://stepgleam.com/guides/get-up-to-speed-on-an-inherited-excel-workbook#step-3)

### Step 4: Trace backwards from the outputs you need

**Tool:** Excel (Microsoft 365)

*"Start at the end result(s) of the doc, particularly the parts that you need directly for your job functions, and walk backwards through the formulas and datasets."* Use **Formulas → Trace Precedents** (click again to go more levels) and **Ctrl+[** to jump to the cells a formula reads.

[Open step 4](https://stepgleam.com/guides/get-up-to-speed-on-an-inherited-excel-workbook#step-4)

### Step 5: Ask Copilot what a sheet is doing, then check its answer

**Tool:** Copilot in Excel

Once you know where to look, ask Copilot to describe a sheet's purpose. A user in the large-workbook thread: *"Copilot can also be used if you ask it to describe what a spreadsheet is trying to do."* Check each claim against the formulas you traced.

**Why this works:** An AI description is a starting point; the traced formulas are the evidence.

**Prompt:**

```
Describe what the Summary sheet calculates and which sheets feed it.
```

[Open step 5](https://stepgleam.com/guides/get-up-to-speed-on-an-inherited-excel-workbook#step-5)

### Step 6: Write your own notes as you go

**Tool:** Excel (Microsoft 365)

*"If there is no documentation then start creating it yourself. This will help you in truly understanding how and why the spreadsheet works."*

[Open step 6](https://stepgleam.com/guides/get-up-to-speed-on-an-inherited-excel-workbook#step-6)

## Pro tips

- Colour the cells that hold typed values, not formulas, so you can see inputs at a glance; one r/excel user suggests exactly that.
- FORMULATEXT shows a formula next to its result.

## Common mistakes

- Changing anything in the original file.
- Starting at the first tab instead of at the output you need.
- Trusting an AI summary without tracing the formulas.

## FAQ

### What if it has circular references?

Trace from the output first, running Trace Precedents several levels deep.

### Can AI read the whole thing for me?

It can describe sheets, but people in these threads still trace the formulas themselves.

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Canonical guide: https://stepgleam.com/guides/get-up-to-speed-on-an-inherited-excel-workbook
Read this guide as Markdown: https://stepgleam.com/guides/get-up-to-speed-on-an-inherited-excel-workbook.md