🧾 Extract PDF invoice data from Gmail into Google Sheets using OpenAI GPT-4o-mini
⚡ 94 views · 🧾 Invoice Processing
Description
Quick overview
This workflow polls Gmail for unread emails with PDF attachments, extracts invoice text, uses OpenAI to pull key invoice fields, and appends the results as a structured row in a Google Sheets “Invoices” ledger.
How it works
- Polls Gmail every 5 minutes for unread emails that include a PDF attachment and downloads the attachment.
- Extracts text from the attached PDF file.
- Sends the extracted text to OpenAI (gpt-4o-mini) to extract vendor, invoice number, dates, amounts, and currency in a strict schema.
- Appends a new row to the Google Sheets “Invoices” tab with the extracted fields plus email metadata (received date, sender, and filename).
Setup
- Connect Gmail, OpenAI, and Google Sheets credentials in n8n.
- Create or choose a Google Sheets document with an “Invoices” sheet and columns like ReceivedDate, FromEmail, Vendor, InvoiceNumber, InvoiceDate, DueDate, Net, Tax, Total, Currency, and FileName.
- Replace YOUR_GOOGLE_SHEET_ID in the Google Sheets append step with your target spreadsheet ID and confirm the sheet name is set to “Invoices”.
Requirements
- Gmail, Google Sheets and OpenAI accounts (credentials connected in n8n); works with born-digital PDFs that have a text layer
Customization
- Narrow the Gmail search query (sender, label, subject) or add fields to the extraction schema (PO number, line items) - both are single settings
Additional info
The extraction prompt is strict by design: the model never invents values - absent fields come back empty, amounts come back as plain numbers. Parsing a typical invoice with gpt-4o-mini costs well under $0.001. Need scanned-PDF OCR, rows posted into QuickBooks/Xero, duplicate detection or an approval step? I build extended versions with async delivery - contact links in my creator profile.
🔗 Nodes Used
Google Sheets, Gmail Trigger, OpenAI Chat Model, Extract from File, Information Extractor
📥 Import
Download workflow.json and import into n8n:
Workflow menu → Import from File