ChatGPT reached 900 million weekly active users (WAU) by February 2026, making it one of the fastest-scaling consumer products in history. OpenAI stopped reporting monthly active users (MAU) in early 2023, strategically switching to WAU as its primary metric — a move that complicates direct comparison with competitors. Based on third-party engagement data, that 900 million WAU figure translates to an estimated 1.1–1.2 billion monthly active users, putting ChatGPT in the same tier as Instagram and WhatsApp. The trajectory from 100 million WAU in November 2023 to 900 million in February 2026 — a 9x increase in 27 months — represents growth without precedent for a non-preinstalled application.
OpenAI has disclosed WAU milestones with increasing frequency, typically timed to funding rounds, product launches, or keynote events. Every figure below comes directly from OpenAI executives or official company communications:
| Date | WAU | Source |
|---|---|---|
| Nov 2023 | 100M | Sam Altman, DevDay keynote |
| Aug 2024 | 200M | OpenAI statement to Axios |
| Oct 2024 | 250M | CFO Sarah Friar, Bloomberg TV |
| Dec 2024 | 300M | Sam Altman, NYT DealBook Summit |
| Feb 2025 | 400M | COO Brad Lightcap on X |
| Mar 2025 | ~500M | OpenAI (confirmed by TechCrunch, CNBC) |
| Aug 2025 | ~700M | Nick Turley, VP of Product, on X |
| Oct 2025 | 800M | Sam Altman, DevDay keynote |
| Feb 2026 | 900M | OpenAI blog post, $110B funding round |
The growth pattern reveals two distinct phases. From November 2023 through December 2024, WAU tripled from 100 million to 300 million — roughly 25% growth per quarter. Then growth exploded: WAU jumped from 300 million to 800 million between December 2024 and October 2025, driven by GPT-4o's image generation going viral in late March 2025. Sam Altman captured the intensity on X: "The ChatGPT launch 26 months ago was one of the craziest viral moments I'd ever seen, and we added one million users in five days. We added one million users in the last hour." COO Brad Lightcap reported that 130 million users created over 700 million images in just days after the Ghibli-style image generation feature launched.
Growth then decelerated — from 800 million in October 2025 to 900 million in February 2026 represents only 12.5% in four months, signaling potential saturation. Analyst Eric Seufert of Mobile Dev Memo noted this slowdown, observing that OpenAI fell short of its internal goal of 1 billion WAU by end of 2025.
OpenAI last reported an official MAU figure in January 2023, when ChatGPT crossed 100 million monthly active users (per UBS/Similarweb data), becoming the fastest consumer application to reach that milestone. The switch to WAU at DevDay in November 2023 was deliberate. Seufert argues the decision serves three strategic purposes: it makes ChatGPT's user base incomparable to competitors who report MAU, it obscures potentially weaker per-user economics, and it masks the churn dynamics inherent in a freemium AI product.
The critical question is the WAU-to-MAU ratio — how many additional people use ChatGPT at least once per month but not every week. Two credible data sources offer estimates:
These two independent sources converge on a 1.1–1.2 billion MAU estimate for early 2026. Cross-referencing with web traffic data (5.35–5.84 billion monthly visits divided by an estimated 5 visits per unique user) produces a roughly consistent ~1.07 billion figure. Some third-party aggregators like Textero.io and Resourcera cite figures near 1 billion MAU as of January 2026, though their methodologies are less transparent.
Notably, ChatGPT's WAU:MAU ratio has improved dramatically — from approximately 50% in mid-2023 to 82% by early 2026, according to Sensor Tower data. This 30+ percentage-point improvement is exceptional. Most apps see engagement ratios plateau or decline as user bases expand. ChatGPT's ratio now approaches Instagram (~92%) and exceeds Gmail (~78%) and Spotify (~79%), suggesting the product has transitioned from novelty to daily utility for most of its user base.
Raw user counts tell only part of the story. OpenAI's internal data, disclosed through an NBER working paper co-authored with Harvard's David Deming and published in mid-2025, reveals that per-user engagement is intensifying, not just expanding.
Message volume provides the clearest signal. Daily messages grew from 1 billion (December 2024) to 3 billion (August 2025) — a 3x increase while WAU roughly doubled from 300 million to 700 million. This means average messages per user per day rose by roughly 50% in that period. By October 2025, OpenAI was processing 6 billion tokens per minute on its API alone. Nick Turley disclosed that ChatGPT handled 18 billion messages per week as of August 2025, implying approximately 25.7 messages per WAU per week.
The NBER study analyzed 1.5 million conversations and found a striking cohort pattern: every signup cohort from Q1 2023 through Q4 2024 showed the same behavior — flat usage through most of 2024, then substantially increasing engagement in late 2024 and early 2025. Early adopters from Q1 2023 were sending 40% more messages per day in July 2025 compared to two years earlier. The researchers concluded this was a "time effect, not a cohort effect" — product improvements (Advanced Voice Mode, o1 reasoning models, image generation) drove increased usage across all cohorts simultaneously.
Session duration averages 13–14 minutes per visit on web, longer than Amazon (8–10 minutes) and most social media platforms. The bounce rate sits at 37–41%, and users average 3.7–4.5 pages per visit. Week 4 retention for new users has improved from ~40% to ~66% over three years — an almost unheard-of trajectory. For comparison, Character AI retains 48%, Gemini 44%, Claude 41%, and Perplexity just 24% at the four-week mark. ChatGPT also exhibits a rare "smile curve" in retention (dips then recovers), a pattern previously observed only in Gmail and Chrome.
OpenAI's leadership has grown increasingly explicit about growth ambitions and financial trajectory. At the December 2024 DealBook Summit, Altman disclosed that more than 10 million users were paying for ChatGPT and that the company was internally targeting 1 billion active users within the next year. CFO Sarah Friar revealed that 5–6% of free users convert to paid, with subscriptions generating 75% of revenue.
By February 2026, the subscriber picture had evolved substantially: 50 million consumer subscribers and 9 million paying business seats, up from 5 million business users in August 2025. OpenAI's blog post accompanying the $110 billion funding round stated that "subscriber momentum accelerated meaningfully to start the year, with January and February on track to be the largest months for new subscribers in our history."
The revenue curve mirrors user growth: $2 billion ARR in 2023, $6 billion in 2024, $20+ billion in 2025, and $25 billion annualized run rate by February 2026 — 3x year-over-year growth that CFO Friar called "never-before-seen growth at such scale." By March 2026, OpenAI was generating roughly $2 billion per month in revenue, and an advertising pilot had already achieved $100 million ARR in just six weeks.
The ambition goes further. At a reporters' dinner in August 2025, Altman stated: "You should expect OpenAI to spend trillions of dollars on data center construction in the not very distant future," and described plans for "billions of people using ChatGPT daily." He noted ChatGPT was already the fifth-largest website globally and aimed to overtake Instagram and Facebook to become third. However, Deutsche Bank analysis projects cumulative losses before profitability could reach $143 billion, with the company not expected to turn cash-flow positive until 2029.
For researchers or analysts attempting to derive MAU from OpenAI's reported WAU figures, the most defensible methodology combines multiple approaches:
The key caveat is that OpenAI defines a weekly active user as anyone who "sent at least one message in the last week." The relationship between this low-threshold metric and meaningful engagement varies — some fraction of monthly users may send only one or two messages before lapsing. Seufert's contrarian position suggests MAU could be as high as 1.8 billion if churn is high and many users cycle in and out monthly, though this scenario is not supported by the Sensor Tower or Similarweb panel data.
ChatGPT's user trajectory from launch to 900 million WAU in just over three years defies conventional scaling patterns. The most significant finding is not the headline user number but the simultaneous improvement in engagement depth: rising per-user message volume, improving retention curves, and a WAU:MAU ratio that strengthened from ~50% to ~82% even as the user base grew 9x. This combination — growing both wider and stickier — is extremely rare in consumer technology.
The best current estimate for ChatGPT's MAU is 1.1–1.2 billion as of early 2026, based on converging evidence from Sensor Tower and Similarweb panel data. OpenAI's strategic choice to report WAU rather than MAU remains a deliberate opacity that serves fundraising narratives while complicating competitive benchmarking. With the 1 billion WAU milestone likely within reach in 2026 and an advertising business already generating revenue, the next inflection point will test whether ChatGPT can sustain engagement growth against an increasingly capable competitive field — or whether it is approaching the natural ceiling of global internet users willing to engage with AI weekly.