The Speed of Years

How much of your life have you already felt?

I'm and expect to live to .

My earliest memory is from age .

How it works

A year feels as long as the share of your life it makes up. At 5, a year is a fifth of everything you've lived. At 50, it's a fiftieth. The philosopher Paul Janet described this in 1877.

Add up a lifetime of shrinking years and you get a logarithm. The count starts at your earliest memory, because that's where the life you can look back on begins:

felt so far = ln(age ÷ first memory) ÷ ln(lifespan ÷ first memory)

Everything is calculated in your browser. Nothing you enter is sent anywhere. A simple visitor counter (GoatCounter) counts page visits without cookies or personal data.

How accurate is this?

Treat the percentage as a thought experiment, not a measurement. Here's what the evidence does and doesn't support.

It's a hypothesis
Janet's idea is almost 150 years old, and no study has measured how long a whole life feels. The number shows what follows if the idea is right.
Surveys only partly support it
People of all ages say days and weeks pass at about the same speed. Older people do say years and decades go faster, but the effect is modest and levels off around middle age. How busy people feel predicts it better than their age does.
The exact curve is unknown
Other versions of the idea bend less. A square-root version (Lemlich, 1975) would put you at 52% instead of 70%.
Memory doesn't follow the curve
The model gives your earliest years the most weight, but most people remember little from before about age 7, and the most from their teens and twenties.
The advice rests on mixed evidence
The link between routine and time shrinking in hindsight is the most direct. The relationship findings come from long observational studies, which show association rather than cause. The awe and meditation results come from small experiments.

The research in more detail

Something new
Looking back, we judge how long a stretch of time was by how many distinct memories it left. Routine makes time shrink in hindsight, and new experiences stretch it. A new trip flies by while you're on it, then feels long when you remember it. Most people remember their teens and twenties best, when so much happened for the first time.
What matters to you
Absorbing, meaningful activity ("flow") is one of the most studied sources of wellbeing. In small experiments, moments of awe made people feel they had more time available.
Other people
The Harvard Study of Adult Development has followed its participants for more than 85 years. The quality of their relationships predicted health and happiness later in life better than anything else the study measured. Emotional moments are also remembered more strongly.
Being present
In one large study, people's minds wandered during nearly half of their waking hours, and they were less happy when that happened. People who had just meditated judged time intervals as longer.

Sources

  1. Janet, P. (1877). Une illusion d'optique interne. Revue Philosophique, 3, 497–502.
  2. Wittmann, M. & Lehnhoff, S. (2005). Age effects in perception of time. Psychological Reports, 97, 921–935.
  3. Friedman, W. J. & Janssen, S. M. J. (2010). Aging and the speed of time. Acta Psychologica, 134, 130–141.
  4. Avni-Babad, D. & Ritov, I. (2003). Routine and the perception of time. J. Exp. Psychology: General, 132, 543–550.
  5. Hammond, C. (2012). Time Warped. Canongate.
  6. Rubin, D. C., Rahhal, T. A. & Poon, L. W. (1998). Things learned in early adulthood are remembered best. Memory & Cognition, 26, 3–19.
  7. Csikszentmihalyi, M. (1990). Flow. Harper & Row.
  8. Rudd, M., Vohs, K. D. & Aaker, J. (2012). Awe expands people's perception of time. Psychological Science, 23, 1130–1136.
  9. Waldinger, R. & Schulz, M. (2023). The Good Life. Simon & Schuster.
  10. McGaugh, J. L. (2004). The amygdala modulates the consolidation of memories of emotionally arousing experiences. Annual Review of Neuroscience, 27, 1–28.
  11. Killingsworth, M. A. & Gilbert, D. T. (2010). A wandering mind is an unhappy mind. Science, 330, 932.
  12. Kramer, R. S. S., Weger, U. W. & Sharma, D. (2013). The effect of mindfulness meditation on time perception. Consciousness and Cognition, 22, 846–852.
  13. Lemlich, R. (1975). Subjective acceleration of time with aging. Perceptual and Motor Skills, 41, 235–238.
  14. Rubin, D. C. (2000). The distribution of early childhood memories. Memory, 8, 265–269.
  15. Urban, T. (2014). Your Life in Weeks. Wait But Why.
  16. Kiener, M. (2015). Why Time Flies, interactive visualization.