I Tested ChatGPT vs. Accurate Digits for Financial Accuracy—Here’s What Happened

Introduction: AI is Advancing – But Can it Really Be Trusted With Your Numbers?

AI has come a long way—astonishingly fast. A little over two years ago, ChatGPT 3.5 burst into mainstream consciousness and transformed how millions of us think about productivity, creativity, and knowledge work. Since then, we’ve seen a steady parade of increasingly sophisticated models (from o1 to GPT-4.5, and the powerful new "Deep Research" mode) offering better reasoning, multimodal capabilities, and even the ability to dynamically execute code.

I started Accurate Digits precisely because—despite these amazing advancements—I knew general-purpose AI still wasn't reliably equipped to verify numerical accuracy in critical reports. Recently, I decided it was time to clearly demonstrate this point. Could today's best ChatGPT models effectively handle something as precise, detailed, and high-stakes as checking an 88-page Annual Financial Report for calculation errors?

To illustrate the difference, I put the latest ChatGPT models head-to-head against Accurate Digits, the specialised tool I designed explicitly for ensuring calculation accuracy. The results, as you'll see, were insightful, surprising, and a strong reinforcement of why specialised tools are crucial for tasks demanding precision and trust.

Why Calculation Errors Matter More Than You Think

Every professional deals with numbers that matter. Whether you're preparing a critical financial report, a sales proposal, or internal metrics for the monthly board meeting, accuracy isn't optional, it's essential. Errors in these documents don't just cause headaches; they lead to incorrect decisions, breakdowns in trust, wasted meetings, and sometimes much bigger problems.

Take accountants, for instance. They're often tasked with preparing high-stakes financial statements—annual reports that investors, regulators, and markets rely on. Even monthly management accounts that summarise financial and operational performance for senior leadership or the board are critical. Yet despite using best-in-class systems like Enterprise Resource Planning Systems (ERPs) and Customer Relationship Management systems (CRMs), gaps in processes and last-mile manual adjustments often allow errors to creep in unnoticed.

But it's not just accountants. The issue extends across virtually every department. Human Resource teams provide key data like employee retention rates, payroll details, and salary information. Errors here can distort budget forecasts, salary reviews, misinform leadership, or derail strategic workforce planning. Sales and Marketing teams present sales funnel metrics, pipeline conversion rates, and forecasting data regularly. A single incorrect calculation can lead to inaccurate forecasting, misguided investment, or misallocation of critical resources.

Consider another high-stakes scenario: complex, manual sales proposals or quotes. These documents often contain dozens, even hundreds, of line items detailing products and services. Even a minor calculation mistake—like a subtotal misalignment or an incorrect total—can lead to underquoting, committing your business to low-margin or loss-making contracts, or at the very least, an embarrassing and potentially damaging conversation with a client about repricing.

The reality is simple: every professional who creates important numerical reports faces these risks daily.

In my experiment, I focused specifically on the accountant’s problem—evaluating how ChatGPT’s latest models and Accurate Digits handled verification of numerical accuracy in an annual financial report. It’s a perfect real-world example that clearly illustrates why specialised tools matter: despite AI’s remarkable versatility, professionals who truly depend on numerical accuracy still need tools explicitly built for the task, like Accurate Digits.

The Experiment: Putting ChatGPT’s Best Models to the Test

To properly evaluate how ChatGPT's advanced models compared to Accurate Digits, I set up a practical, realistic test designed to reflect exactly how most professionals might approach this challenge in real life.

The task: verifying numerical accuracy in an 88-page annual financial report from an Australian-listed company, fully audited and publicly available. For the test, I focused specifically on ChatGPT's latest models—including GPT-4o-mini, GPT-4o, GPT-4.5, GPT-o3-mini-high, GPT-o1, and even the specialised "Deep Research" mode—comparing their performance directly against Accurate Digits.

Prompting matters enormously when using ChatGPT, and initially, I thought my first prompt was straightforward:

“You are an auditor. Review the financial statements attached and document any inaccuracies found. Be sure to show full audit trail behind each number checked including numbers which are errors and those that are correct.”

However, responses quickly revealed significant practical challenges. The models consistently misinterpreted the request. For example, GPT-4o-mini inexplicably delivered an analytical review rather than checking calculations. GPT-o1 returned a narrative response without clear calculation verification. The Deep Research model was better clarifying what I needed but still proceeded to provide a response outside of the table structure we landed on.

Realistically, how many professionals crafting such prompts would get them exactly right on the first attempt? And even after clarifying follow-ups, ChatGPT models still showed considerable inconsistency and confusion.

Recognising these practical difficulties, I refined the prompt significantly for a second, clearer attempt:

“Conduct a comprehensive financial audit of all numerical data in the attached annual report. Verify all reported figures against their implied calculations to ensure accuracy. This includes all financial data contained in the report, such as financial statements, notes, segment reporting, key metrics, remuneration, and any other numerical disclosures. For each calculation, document the findings in a structured CSV format with the following columns:

• Page Number
• Description
• Reported Figure
• Calculated Figure
• Full Workings for Calculated Figure (break down all components)
• Variance (difference between reported & calculated figures)
• Correct? (Yes/No)
• If any discrepancies are found, highlight them with a clear explanation. Ensure that all results are exported to a CSV file for review.

Yet, even with this explicitly detailed instruction, ChatGPT's advanced models struggled. GPT-4o returned mostly extracted text marked "pending calculation" without actual verification. GPT-o3-mini-high admitted outright the request was beyond its practical capabilities:

“This is a massive audit of all figures in the report covering everything. A full audit would require a huge number of CSV rows, which would go beyond the scope here. However, I can produce a sample CSV with key checks like revenue growth, EBITDA margins, cashflow and net assets.”

To give ChatGPT the best possible chance, I even simplified the task at one point, asking models just to verify a single page—the profit and loss statement. Yet even this less realistic scenario, isolating just one of 88 pages, produced surprisingly incomplete and unreliable results.

By contrast, Accurate Digits didn't require complex prompting or adjustments—it was specifically designed for precisely this kind of task. I simply uploaded the report, and Accurate Digits rapidly processed and highlighted calculation errors clearly and consistently on the original document itself.

ChatGPT is Great at Many Things - But Not This

1 Summary analysis of Accurate Digits versus ChatGPT when reviewing financial accuracy.

What the Data Reveals: How ChatGPT Really Verify Your Numbers?

After thoroughly testing ChatGPT’s latest models head-to-head against Accurate Digits, the results were clear—and very revealing. Here are the key insights distilled into practical terms:

1. Accuracy: Precision Matters

ChatGPT Struggled With Frequent Errors and Hallucinations
Despite their sophistication, ChatGPT models consistently produced unreliable and misleading results. Even when dynamically running code to verify calculations (the "operator" feature), these models frequently hallucinated outcomes or made basic calculation errors.

For example, GPT-4o-mini incorrectly calculated a percentage change as -44.8% instead of the correct -44.7%. Admittedly a slight error, but an error a calculator would never make. Worse, this metric wasn't even in the original report. ChatGPT confidently generated a non-existent calculation. 

1 GPT-4o-mini incorrectly calculated a percentage change as -44.8%. When verified with a calculator, the actual calculation was -44.675...%—which rounds to -44.7%, not -44.8%. This is a hallucination. A calculator would never make this error.

2 Worse still, this percentage change of -44.8% doesn't even exist in the original report.  ChatGPT created and confidently asserted accuracy for a number that was never there to begin with.

Accurate Digits Found Real Errors That Others Missed
In stark contrast, Accurate Digits identified and verified 716 calculations in under four minutes, pinpointing critical errors even within previously audited financial statements:

• Miscalculated Underlying EBITDA margins
• Balance Sheet discrepancies affecting key Parent Entity disclosures
• 16 separate instances of subtle rounding and signage mistakes (negative vs positive numbers)

Because Accurate Digits evaluates formulas exactly like a calculator, results are repeatable, structured, and trustworthy—with zero hallucinations or guesswork.

1 This analysis from Accurate Digits, generated after reviewing the annual report, highlights a miscalculated Underlying EBITDA margin for FY23. The review confirms the correct figure should be 28%, not the reported 30%, demonstrating how Accurate Digits detects critical financial discrepancies with precision.

2 This screenshot from Accurate Digits highlights Total assets is miscalculated for 30 June 2024. The analysis reveals the correct figure should be $29,794,000 not the reported $29,974,000.

3 This screenshot from Accurate Digits highlights Assuming the reported Total assets value is correct, Net assets is miscalculated for 30 June 2024. The analysis reveals the correct figure should be $29,966,000 not the reported $29,786,000.

4 This screenshot from Accurate Digits report highlights Software at 30 June 2024 has a rounding difference of $1,000 (rounded to closest $1,000). It should calculate to $71,000 not the reported $72,000.

2. Speed & Efficiency: Why Wait?

Accurate Digits verified 716 calculations across an 88-page report in 3 minutes and 58 seconds—that’s more than 3 calculations checked per second.

ChatGPT’s best attempt was significantly slower and incomplete at only 0.11 calculations checked per second only.

1 Accurate Digits outpaces AI models by a wide margin, performing financial checks 30x faster than ChatGPT best performing models. While ChatGPT struggles with complex calculations, Accurate Digits delivers rapid, precise results in real time.

In practical terms:

• Accurate Digits: Complete accuracy check in under 4 minutes.
• ChatGPT: Partial, inconsistent, and largely unusable results even after 17 minutes.

3. Prompting: Complexity vs. Simplicity

ChatGPT Required Endless Prompt Refinements
No matter how clear or precise the instructions, ChatGPT repeatedly misunderstood even straightforward requests. Models often produced entirely unrelated outputs—such as GPT-4o-mini delivering analytical reviews instead of verifying calculations, and GPT-o1 returning lengthy narrative responses without structured calculation verification.

Professionals don’t have time for endless tweaking, revising, and troubleshooting just to get basic calculations checked.

Accurate Digits Needs No Prompting at All
Simply upload your document, and Accurate Digits automatically reviews it—no instructions required. The process is seamless, repeatable, and consistently accurate from the very first use.

4. Consistency: Predictability Matters

ChatGPT’s Wildly Unpredictable Methods & Results
ChatGPT models produced highly inconsistent outcomes—even when given identical data and instructions. Their approaches varied dramatically:

• Sometimes they relied on built-in OCR, other times dynamically generated Python code.
• Calculation verification methods constantly shifted—from direct AI evaluation, to Python-based verification, then back to AI-generated text summaries, frequently reintroducing hallucinations.

Results were equally unpredictable, ranging from structured lists, narrative summaries, markdown tables, to incomplete CSV files—often without clear references back to the original document. For professionals, these shifting responses mean confusion, wasted time, and lack of trust.

1 Here is an extract of a response from ChatGPT 4o-mini. Its evident that this response is more like an analytical review of balances movements rather than verifying the underlying numbers for inaccuracies.

2 ChatGPT 4o provided a table of data that can be downloaded as a CSV. Its a step in the right direction, but the data is incomplete to allow thorough review of the checks performed.

3 ChatGPT 4.5. generated a response in the canvas mode (not in the normal chat window). The response was a list of the checks performed, though a closer look reveals that the last couple aren't actually conducting a check.

4 ChatGPT o1 delivers a narrative-style response, grouping multiple calculations into a single paragraph rather than presenting them in a structured format. 

5  ChatGPT 4o's Deep Research mode outputted to a CSV, but in a different format from the table based CSVs provided by other models - highlighting inconsistencies in structured data generation.  

Accurate Digits Delivers Consistency & Clarity
Every time you run Accurate Digits, you get the same clear, structured output—verified calculations and potential errors directly annotated on the original document. It also summarises checks performed, making review effortless.

For an interactive demo showcasing the clear and consistent outputs provided by Accurate Digits, check out this interactive demo.

5. Ability to Handle Large Reports: Built for Real-World Use

ChatGPT: Clearly Overwhelmed by Complex Documents
ChatGPT models struggled significantly with larger documents. Most could identify fewer than 8 calculations across the entire 88-page financial report. Even Deep Research mode, the most sophisticated available, took between 9–17 minutes per run and produced mostly unusable results.

One advanced model (GPT-o3-mini-high) openly admitted these limitations, stating transparently:

“This is a massive audit of all figures in the report covering everything. A full audit would require a huge number of CSV rows, which would go beyond the scope here. However, I can produce a sample with key checks like for revenue growth, EBITDA margins, cashflow and net assets.”

Accurate Digits: Scalable, Fast, Reliable
Accurate Digits effortlessly handled the entire 88-page report, identifying 716 calculations in under 4 minutes. It scales easily—whether your document is one page or hundreds, Accurate Digits maintains speed, reliability, and ease-of-use.

6. Privacy & Data Security: Keeping Your Information Safe

1 Privacy Comparison: ChatGPT requires opt-out to prevent data sharing, while Accurate Digits never uses customer data for AI training and deletes uploads within one business day.

* Refer to our privacy policy to see the full details. 

7. Cost & Value: Paying Less, Getting Much More

1 Pricing Comparison: ChatGPT Plus costs $31 AUD per month with low accuracy and slow performance, while ChatGPT Pro is significantly more expensive at $318 AUD, yet still incomplete. In contrast, Accurate Digits starts at $25 AUD, delivering high accuracy, speed, and consistency for financial checks.

Accurate Digits doesn’t just deliver superior performance—it does so at significantly lower cost compared to even basic ChatGPT subscriptions, let alone premium AI packages.

The Verdict: General AI is Great at Many Things – But Not This

1 Accurate Digits vs. ChatGPT: For financial accuracy, speed, and consistency, Accurate Digits delivers where AI models fall short. Choose the right tool for reliable financial analysis.

The results of this test clearly underline one of the most critical lessons for professionals relying on numerical accuracy: general-purpose AI, no matter how powerful or versatile, is simply not yet suited to reliably verify calculation accuracy in critical documents.

1 An optional caption for the image that will be added to the gallery. Enter any descriptive text for this image that you would like visitors to be able to read.

ChatGPT’s latest and most sophisticated models showed significant and practical limitations when tested against Accurate Digits. Specifically:

• Inconsistent Results: Each ChatGPT model approached the same task differently, sometimes producing useful responses, but more often returning confusing, incomplete, or inaccurate results.
• Frequent Errors and Hallucinations: Even advanced models struggled to verify calculations correctly, often confidently providing incorrect information.
• Impractical for Real-World Use: The time, cost, and complexity of prompting ChatGPT effectively make it an impractical solution for busy professionals who need quick, trustworthy results.

In contrast, Accurate Digits clearly demonstrated the value of specialised tools:

• Reliable Accuracy: It found genuine calculation errors missed by standard audit processes.
• Speed and Efficiency: It delivered consistent, precise verification of 716 calculations in under 4 minutes.
• Ease-of-Use: Accurate Digits needed no complex prompting, just upload your document and receive immediate, actionable results.
• Cost-Effective: At just A$25/month, Accurate Digits provides exceptional value, significantly outperforming even the premium ChatGPT offerings.

The key insight is simple yet powerful: when accuracy truly matters, general-purpose AI tools alone can't guarantee the results professionals need. Specialised tools like Accurate Digits exist precisely because these high-stakes numerical tasks require dedicated solutions built explicitly to handle them with precision and reliability.

For an interactive demo showcasing Accurate Digits, check out this interactive demo.