--- title: "How much faster do people finish writing tasks with AI, and is the work better? (25–40%) | The AI at Work Fact Book" description: "With AI, professionals finished defined writing tasks 25 to 40 percent faster and graders rated the work 18 to 34 percent better. Experiments, the field-trial contrast and misquoted figures." url: "https://evy.so/facts/ai-writing-speed-and-quality/" last_updated: "2026-10-16" --- F-09 · What AI Saves # How much faster do people finish writing tasks with AI, and is the work better? In controlled experiments, professionals using ChatGPT or GPT-4 finished defined writing and consulting tasks 25 to 40 percent faster, and graders rated the work 18 to 34 percent better. In a six-month field trial of everyday work, time spent writing documents did not change measurably. 25–40% less time on a defined writing or consulting task, with quality up 18 to 34% - Medium confidence - 3 primary sources - 2023 to 2026 - Last checked October 14, 2026 ## Cite this EVY (2026). How much faster do people finish writing tasks with AI, and is the work better? The AI at Work Fact Book, F-09. https://evy.so/facts/ai-writing-speed-and-quality/ (last checked October 14, 2026). CC BY 4.0. Copy citation [Data as JSON](https://evy.so/facts/ai-writing-speed-and-quality.json) [Markdown](https://evy.so/facts/ai-writing-speed-and-quality.md) ## How to read it Both experiments time one well-defined task, chosen to suit the AI, in a single session. Noy and Zhang's task took people without AI about 27 minutes; the BCG tasks were longer, multi-part consulting exercises. Quality was graded on different scales (1 to 7 and 1 to 10). The six-month field trial found no change in time in Word, though its authors say too few people used Word regularly to detect small effects. ## Every study on one scale Shaded: 25–40% One figure A range in one study Chart values as text - Scale: % less time on the task. Shaded range: 25–40%. - Noy and Zhang (2023): 40% less time - Dell'Acqua et al., BCG (2026): 22.5–27.6% less time **Why medium confidence:** Two independent teams with different designs agree on direction and roughly on size. Both time one-off tasks chosen to suit the AI, and the one long-run field trial finds no measurable change in document time. Studies without a figure on this scale are listed in the table only. ## Sources Sources for F-09 | Study | Creator | Year | Sample | Method | Figure | Link | | --- | --- | --- | --- | --- | --- | --- | | Experimental evidence on the productivity effects of generative artificial intelligence (Science) | Shakked Noy and Whitney Zhang (MIT) | 2023 | 453 college-educated professionals: marketers, grant writers, consultants, data analysts, HR professionals and managers | Preregistered online randomized experiment on a 20 to 30 minute writing task, graded blind by people in the same occupation. Minute figures from the authors' MIT working paper. | 40% less time and 18% higher quality; in the working paper, 27 minutes without ChatGPT and 17 with it “The average time taken decreased by 40% and output quality rose by 18%.” | [science.org ↗](https://www.science.org/doi/10.1126/science.adh2586) | | Navigating the Jagged Technological Frontier (Organization Science) | Fabrizio Dell'Acqua, Ethan Mollick, Karim R. Lakhani and colleagues (Harvard Business School, Wharton, MIT, Warwick, Boston Consulting Group) | 2026 | 758 BCG consultants, about 7% of its individual-contributor consultants | Preregistered randomized experiment on 18 realistic consulting tasks, graded by humans | 25.1% faster on average (22.5% and 27.6% in the two AI groups), 12.2% more tasks done, quality up 29.9% to 33.9% “completing 12.2% more tasks and completing them 25.1% more quickly on average” | [doi.org ↗](https://doi.org/10.1287/orsc.2025.21838) | | Shifting Work Patterns with Generative AI (NBER Working Paper 33795) | Dillon, Jaffe and Immorlica (Microsoft Research) and Stanton (Harvard Business School) | 2025 | 7,137 knowledge workers at 66 large firms | Randomized field experiment over six months, timed with Microsoft 365 usage data | No significant change in time spent writing in Word, and the same number of documents completed “no significant average changes in total time spent in video meetings or writing documents” | [nber.org ↗](https://www.nber.org/papers/w33795) | Quality ## Is writing done with AI better? Graders rated it higher in both experiments: 18% higher in Noy and Zhang's study, graded blind by professionals in the same occupation, and 29.9% to 33.9% higher in the BCG study, graded by humans (about half that when GPT-4 did the grading). In Noy and Zhang's study, 68% of people with ChatGPT handed in its first draft without editing it. When it flips ## What happens on tasks the AI handles badly? The gain can turn into a loss. On a business problem chosen so that GPT-4 would give a plausible wrong answer, BCG consultants without AI were right 84.5% of the time, against 60% and 70.6% in the two AI groups, even though the AI groups spent less time on it. F-13 covers this in more detail. ## Numbers you may have seen These figures circulate widely. Here is what the original source says. - **ChatGPT makes workers 40% more productive (Noy and Zhang).** The study found 40% less time and 18% higher quality, on one 20 to 30 minute writing task. A 40% cut in time is a different number from a 40% rise in output. - **AI raised BCG consultants' quality by more than 40%.** That comes from the 2023 working paper. The peer-reviewed 2026 version reports human-graded gains of 29.9% to 33.9%. - **Consultants using AI were 19% less likely to be correct.** The paper's tables give 84.5% correct without AI and 60% and 70.6% with it: a drop of 14 to 25 percentage points, 19 on average, on one task chosen to sit outside the AI's abilities. ## More from What AI Saves - [F-08**3–5.4%**How much time does AI save knowledge workers?](https://evy.so/facts/time-saved-by-ai-at-work/) - [F-10**14–15%**How much more do customer support agents get done with AI?](https://evy.so/facts/ai-customer-support-productivity/) - [F-11**21–26%**How much faster do developers code with AI assistants?](https://evy.so/facts/ai-coding-speed/) - [F-12**27–46%**Does AI help less-experienced workers more than experienced ones?](https://evy.so/facts/ai-helps-less-experienced-workers-more/) - [F-13**14–25%**When does AI make work slower or worse?](https://evy.so/facts/when-ai-makes-work-worse/) [The whole chapter](https://evy.so/facts/what-ai-saves/) · [Chapter poster](https://evy.so/facts/what-ai-saves/sheet/) · [All of The AI at Work Fact Book](https://evy.so/facts/)