Comparing NatSheets, ChatGPT, and Claude for Advanced Data Analysis
Have you ever struggled to quickly and accurately analyze data across multiple spreadsheets and complex datasets? You're not alone! Today, we're comparing our newly launched platform NatSheets with two established AI assistants—ChatGPT and Claude—by using a challenging real-world example: calculating the Extended Internal Rate of Return (XIRR) for a stock portfolio. Let's see how they stacked up!
The Challenge
We presented each platform with identical spreadsheet files:
- Vested_Holding.xlsx: Current US stock portfolio holdings
- Vested_Transactions.xlsx: Complete transaction history (purchases, sales, dividends, etc.)
And gave them all the same prompt:
Based on my US Stocks Holdings and Transactions, calculate the XIRR for each ticker, add it as a new column in the holdings sheet, and sort them by XIRR in descending order.
Why XIRR Makes a Perfect Test Case
XIRR (Extended Internal Rate of Return) measures investment performance accounting for all cash flows at their specific dates. It's an excellent benchmark for AI analysis platforms because it:
- Requires working with multiple files simultaneously
- Demands precise handling of various transaction types
- Involves complex date-based cash flow calculations
- Tests error-handling capabilities
- Challenges the platform's ability to present results clearly
Here's how each platform performed:
| Feature | ChatGPT Free | ChatGPT Plus | Claude Pro | NatSheets Free |
|---|---|---|---|---|
| File Processing | Server | Server | Local (Browser-only) | Local (Browser-only) |
| Calculation Accuracy | Errors Out | Incorrect (6-digit XIRRs) | Mostly Correct | Highly Accurate |
| Export Capability | No | Yes (Incorrect Data) | Manual Copy-Paste | Direct Download |
| Processing Time | N/A (Failed) | Several Minutes | ~7-8 Minutes | ~25 Seconds |
| Data Privacy | Low (Uploaded) | Low (Uploaded) | High (Local) | High (Local) |
| Visualization Included | No | No | Requires Extra Prompt | Yes |
Platform-by-Platform Breakdown
ChatGPT
ChatGPT Free
The free version uploaded files to OpenAI's servers and attempted to process them using Python. Unfortunately, it hit multiple errors while parsing the data and eventually reached its processing limit without completing the analysis. See the chat.
ChatGPT Plus ($20/month)
The premium version (using GPT-4o) initially showed promise. However, after processing the files, it produced wildly inaccurate XIRR values—some impossibly high at six digits! A second attempt using GPT-4.1 yielded similarly incorrect results. See the chat.
Verdict: ✗ Slow processing with inaccurate results despite the premium price tag.
Claude
Claude Free
The free version doesn't support Excel file uploads, so it couldn't attempt the task.
Claude Pro ($20/month)
Claude took a privacy-conscious approach by analyzing the files locally with JavaScript instead of uploading data to external servers. After working through some initial challenges, it produced mostly correct XIRR values. The main drawbacks were the 7-8 minute processing time and the cumbersome export process, which required manually copying and pasting CSV data. See the chat.
Verdict: ✓ Produces generally correct values with good privacy protection, but the process is slow and exporting results is awkward.
NatSheets
NatSheets Free
NatSheets handled the task differently. After quickly importing the files (which never left the browser), it completed the entire XIRR analysis in approximately 25 seconds. It automatically created an updated spreadsheet with the sorted XIRR values and included a visualization chart for immediate insights.
When checking accuracy, NatSheets couldn't compute XIRR for four stocks with extreme negative returns (around -80%), which Claude managed to calculate. For one stock (AXP), NatSheets calculated a 690% XIRR while Claude showed 99%. After manual verification, NatSheets proved accurate (689% when calculated by hand) due to the short holding period (44 days) and substantial returns.
For the stocks NatSheets skipped, further research confirmed that XIRR calculations often struggle with extreme negative returns or unusual data patterns.
Verdict: ✓ Fast, accurate, user-friendly, and completely privacy-focused.
Why NatSheets Wins This Challenge
- True Privacy Protection: Your spreadsheet data never leaves your browser - only metadata (column names and data types) is transmitted, unlike other platforms that require uploading your financial information.
- Superior Speed: From import to results in under 30 seconds, compared to several minutes with other platforms.
- Better Accuracy: Results closely matched manual verification where it mattered most.
- Complete Solution: Provides direct file downloads and automatic visualizations without extra steps.
- Free Tier Advantage: Accomplishes what premium subscriptions on other platforms struggle to do, at no cost.
Final Thoughts
While ChatGPT and Claude excel as general-purpose AI assistants, NatSheets demonstrates clear superiority for specialized spreadsheet analysis. Its unique design allows you to transform how you interact with and analyze spreadsheet data through natural language conversation, regardless of your technical background. The combination of speed, accuracy, privacy protection, and intuitive results presentation makes it the standout choice for financial and data analysis tasks.
Try NatSheets today at natsheets.com/new and see how it can transform your approach to spreadsheet analysis!