excel-model-builder

Excel Model Builder

Overview

Creates structured spreadsheets and financial models with formulas, formatting, and clear documentation. Outputs ready-to-use Excel files or Google Sheets templates.

Workflow

Step 1: Define the Model

Ask the user:

1. Purpose: What decisions will this model inform?
2. Type: Financial projection, budget, tracker, calculator, or dashboard?
3. Inputs: What data will be entered?
4. Outputs: What numbers/insights do you need?
5. Time horizon: Monthly, quarterly, annual?
6. Format: Excel (.xlsx) or Google Sheets formula format?

Step 2: Design the Structure

Standard model layout:

Tab	Purpose
Dashboard	Summary view with key metrics
Assumptions	All inputs in one place (change here, model updates)
Revenue	Revenue projections and breakdowns
Costs	Cost structure and projections
P&L	Profit & Loss statement
Cash Flow	Cash flow projections (if needed)

Step 3: Build with Formulas

Rules for good models:

1. Inputs highlighted (yellow cells = editable)
2. No hardcoded numbers in formulas — reference the Assumptions tab
3. Clear labels for every row and column
4. Consistent formatting (currency, percentages, dates)
5. Error handling with IFERROR()
6. Named ranges for key assumptions

Step 4: Create the Spreadsheet

Use openpyxl (Python) to generate .xlsx files with:

• Multiple tabs
• Formulas (not just values)
• Conditional formatting
• Number formatting
• Headers and borders
• Print-ready layout

Output

Generate actual .xlsx file with:

• All formulas intact
• Formatting applied
• Sample data that can be replaced
• Instructions tab explaining how to use it

Quality Checklist

• [ ] All inputs on one tab (Assumptions)
• [ ] No hardcoded numbers in formulas
• [ ] Yellow highlighting on editable cells
• [ ] Dashboard shows key metrics at a glance
• [ ] Formulas use cell references (not typed values)
• [ ] Error handling on division formulas
• [ ] Instructions included