About Longlevity

Most of us have no real sense of how much time we have left. So we put off the walk. Grab whatever's easy for dinner. Let months slide by without calling the people who matter most. Not because we don't care, because none of it feels urgent.

Then you see a number. Your number. Not a vague "live healthier" nudge, but an estimate grounded in CDC life tables and decades of mortality research. If you're 40, that's roughly 15,000 days. Maybe 400 more visits with your parents. That kind of clarity doesn't create anxiety. It creates intention. That's the entire idea behind Longlevity.

The engine is the product

Anyone can get a lifespan number today. A quiz will give you one, and so will a chatbot. What neither gives you is a model, and the model is the whole difference between a number you can act on and a number that changes with the weather.

Longlevity is an engine, and this is what is in it. The baseline is the CDC's own life table (United States Life Tables 2024), conditional on the age you have already reached, with a cohort adjustment so younger people are not undercounted by frozen mortality rates. Ten factors are layered on it, each anchored to a named study and applied at the conservative end of its evidence. Habits overlap in their biology, so gains are discounted rather than added up, with the whole-lifestyle ceiling anchored to the best combined-lifestyle study we have.

Every result carries a version number (engine 2.2.3, calibration 2026.10.1 today), every saved estimate records the version that produced it, and when the engine improves your history is re-scored from your original answers.

The habit library behind the report has a graded primary source on 99 of 167 actions, and every one of them is safety-screened. Each release is swept across 648 combinations of age, sex, weight and habit profile, and about two thousand complete reports are rendered and checked for contradictions before it ships.

Then we read the research again, every month, and publish every review and release, including the ones that changed nothing and the mistakes we found in our own work. That is the work you are not doing when you take the assessment, and it is the reason to use Longlevity instead of prompting your way to a guess.

Why we built this

We went looking for a longevity tool we could trust, and couldn't find one.

The free calculators were mostly quizzes with no research behind them, or funnels for supplements. The rigorous versions sat behind $2,000 memberships at private longevity clinics. Nothing in between translated the actual mortality literature into a personal estimate you could act on today.

So we read the key studies behind each habit, built a calculator that weights every answer by the effect sizes those studies found, kept every number deliberately conservative, and made it free. The whole method is public, down to the version number of the model that produced your result.

What you get

Your age, then a dozen questions. Your sex, the nine habits with the strongest mortality evidence, your body weight and your family history. It takes about two minutes. You see your estimated lifespan and how it compares against the average. You can share your result, compare with the people you love, and read the research behind the habits in the free library.

All of that is free, always, along with a free account and unlimited re-measuring. Save your results and once a year we'll invite you back to re-measure and see how the year treated you. Think of it as an annual longevity physical.

Everything is free for everyone, including the Longlevity Report, which turns your results into a plan. It holds your biological age, your potential and your biggest lever by name, with every habit ranked by the years on the table, how each habit impacts your biological age, your three priorities with evidence behind each, science-backed actions picked for you, your projection with and without the changes, and a 90-day plan you can print and follow. Nothing is for sale and nothing is locked. If a report was worth something to you, there is a support line at the end of it, and it unlocks nothing.

What we believe

Generic health advice rarely moves anyone. A concrete number does. When you see that your trajectory is 79, and you could be at 85 if you fixed two specific things, the math has a weight the slogans don't.

The habits that extend life aren't dramatic. The research keeps pointing at the same unglamorous things: sleep, movement, food that isn't ultra-processed, people you trust, a reason to get out of bed. Longlevity's job is to show which of those matter most for you, based on where you are today.

And the point of living longer isn't the number. It's the shared time it buys: more trips home, more dinners with your kids, more of the people who make it worth being here. That's why the calculator has a Compare feature, so you can see how many years you have left with the people you love and let that shape what you do with them.

What we will never do

• Sell your data. Your answers produce your results and nothing else.
• Push supplements, protocols, or products. We have nothing to sell you.
• Charge you. Everything is free. A support payment is voluntary, never renews, and is refundable for 30 days, no questions asked.
• Inflate a number to motivate you. We do not round up, and the combined size of the adjustments is calibrated to a study that measured the habits together. We would rather you be pleasantly surprised than misled.
• Pretend to be your doctor. Longlevity is an educational tool. It doesn't diagnose or treat anything.

The science

Every adjustment in the calculator maps to a specific published study: randomized trials where they exist, the largest recent meta-analyses otherwise, with Li's combined-lifestyle study as the calibration anchor and CDC national life tables as the baseline. Habits overlap in their biology, so we discount for interactions rather than adding gains up, and younger users get a cohort adjustment so frozen mortality tables don't undercount them.

We re-read the research every month. When the evidence moves, the model moves with it, and every change is versioned so you can see what shifted and why. The full study list, the effect sizes, and an honest account of what Longlevity can't tell you are on the methodology page.

Who runs this

Longlevity is built and operated by Citron Labs LLC. We are not medical professionals, and Longlevity is not a medical device or a substitute for professional medical advice. Use it to inform conversations with your healthcare provider, not to replace them.

Every claim on this site traces to a primary study, never to another blog. There is no sponsored content. Our editorial standards are public.

Contact

A question, a correction, a study you think we should cite? Email contact@longlevity.ai. We read everything. The FAQ covers most common questions; press and partnerships reach us at the same address.

Go deeper: how the estimate is calculated, the seven longevity archetypes, or the blog.