How to Compare Contract Versions and Spot Changes

Why compare instead of rereading?

When a contract goes back and forth between parties, each new version can include small but crucial changes: a 30-day deadline becomes 60 days, "may" becomes "must," a penalty percentage changes, or an entire clause disappears. Rereading the whole document to find these changes is tedious and unreliable because your brain tends to see what it expects.

The comparison automatically highlights every difference between the original and the new version. You can keep reading, but focus only on what changed.

Compare PDF contracts

1. Open Compare PDF.
2. Select both files: first, the original version (the one you already approved or sent), then the new version.
3. Choose to compare page by page (best when the layout hasn’t changed) or the entire document (better when adding a paragraph pushes the rest of the text onto following pages).
4. Click Compare PDFs. Removed and added content will be highlighted.
5. Download the report to save it or send it to your lawyer.

The comparison uses the text in the PDF. If either file is a scan, run it through PDF OCR first. Without that, there’s no text to compare.

Contracts in Word or Google Docs

• Word: On the Review tab, click Compare › Compare. Choose the original and revised documents. Word creates a third document with the changes marked, similar to Track Changes.
• Google Docs: With the new version open, go to Tools › Compare documents and choose the original from Drive. The result is a new document with suggestions showing what changed.
• Text excerpts: To compare just one clause or text you received by email or message, paste both versions into Compare Text.

If one version is in Word and the other is a PDF, extract the PDF text with PDF to Text, then compare the two texts.

What to review extra carefully

Not all differences matter equally. When reviewing the results, focus on:

• Amounts, percentages, and rates for increases, penalties, and interest.
• Deadlines: contract term, notice period, and payment and delivery dates.
• Words that express obligations: “may” and “must,” or “optional” and “required,” can change the meaning of an entire clause.
• Parties and identifying details: company name, registration number, address, and representative.
• Jurisdiction and termination: where potential disputes will be resolved and the conditions for ending the contract.
• Attachments: changes often appear in an attached price list or scope of work, not in the contract itself. Compare the attachments, too.

Limitations and precautions

• Formatting: These tools compare text. Changes to bolding, color, or spacing may not show up, and usually don’t matter.
• Line breaks: If text has been rearranged into columns or tables, the comparison may flag changes that are only due to positioning. Compare the entire document instead of page by page to reduce this noise.
• Correct versions: Make sure the “original” really is the latest version you approved. Comparing against an old draft can mix previously discussed changes with new ones.
• Not a substitute for legal advice: The comparison shows what changed. For important contracts, a lawyer should assess whether the changes are acceptable.

Example: lease renewal

You receive a lease renewal draft from your property manager, described as “the same as before, just with a new date.” When you compare the old lease with the draft, the tool highlights:

• the effective date, as expected;
• the rent adjustment rate, which changed from one index to another;
• a new sentence in the maintenance clause, making the tenant responsible for repairs that were previously the landlord’s responsibility.

Without the comparison, the last two changes could easily slip past in a quick read. With the report in hand, you can bring up those specific points and request corrections before signing.

Frequently asked questions