12tldr is a free AI article summarizer. Paste any article URL and get a structured summary with TL;DR bullet points, context, key details, and why it matters — all in seconds.

How does 12tldr work?

Paste an article URL into the input field and click Summarize. Our AI reads the article and generates a clear, structured summary. No signup or account is required.

Is 12tldr free to use?

Yes, 12tldr is completely free. No account, no subscription, no tracking required.

Which websites does 12tldr support?

12tldr works with articles from most major publications including The Economist, New York Times, Bloomberg, BBC, Reuters, The Guardian, Wired, and thousands of other websites.

What does the AI summary include?

Each summary includes a TL;DR with three bullet points, a 'What it's about' section, 'The details' with key facts, and 'Why it matters' — giving you a complete picture without reading the full article.

Should you track your VO2 max?

Source: economist.com

The article questions whether people should track their VO2 max, a measure of how much oxygen your body uses during intense exercise.
Devices like smartwatches now estimate VO2 max easily, but accuracy varies and it mainly predicts health risks for fit people.
Tracking it might motivate some to exercise more, yet it can also discourage others if scores drop.

The article explores the trend of consumer gadgets tracking VO2 max, debating its value for everyday fitness enthusiasts. It involves scientists, athletes, and companies like Apple and Garmin that build these features into watches. The core finding is that while VO2 max reliably signals heart disease risk in healthy people, casual tracking often lacks precision and may not improve habits. Readers care because millions use these devices daily, hoping for better health insights.