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How Sandglass calculates your time lived and remaining

Published on 17 October 2026 · Updated on 28 October 2026 · Sandglass Team

Sandglass is a tool for reflection, not prediction. Here we explain transparently how its calculations work, where the data comes from and what its limits are.

The three starting inputs

1. Your region: you choose from nine large regions of the world. Each has an associated indicative life expectancy, rounded from public statistics.
2. Your date of birth: it is used to calculate your exact age in years, days and hours.
3. Life expectancy: it starts with your region's value, but you can adjust it between 55 and 95 years with a slider, for example if you want to use a more optimistic or more cautious scenario.

How the remaining time is obtained

The calculation is a subtraction: the chosen life expectancy minus your current age. If your age is above the life expectancy on the slider, the tool tells you and shows you which life expectancy you would need to keep seeing results. From the remaining time, the equivalents in months, weeks and days are obtained.

The breakdown of your time

Next you can turn on activities such as sleeping, working, using your phone, personal care, transport, eating and cooking or household chores, and even add your own. For each one you enter how many hours a day you spend on it and Sandglass multiplies them by the remaining days of life. The chart shows what part of your future time each activity takes up and how much is left free. If you add up more than 24 hours a day, the tool warns you so you can adjust the values.

The time "Wrapped"

At the end, the "Discover my Wrapped" option generates a sequence of curious facts about your own time, different each time, and lets you download a card with the summary to keep or share.

Privacy: everything happens in your browser

Calculations are carried out entirely on your device. Your date of birth and your daily hours are not sent to any server or stored in a database: there are no accounts or sign-up. The only thing your browser may remember is your language preference. You can read more in the privacy policy.

Limits worth knowing

• Life expectancies are rounded regional averages; within a region there are large differences between countries and people.
• The tool does not predict how long you will live and has no medical purpose.
• Activities are added up independently; in real life some overlap.
• The results are illustrative and meant for gaining perspective, not for making health decisions.

The formulas we use

All the calculation is based on simple arithmetic operations, which you can reproduce with a calculator:

• Age in years: full years elapsed between your date of birth and today.
• Remaining time: chosen life expectancy minus your age.
• Remaining days: remaining years × 365.25 (the average value includes leap years).
• Remaining weeks: remaining days ÷ 7. Remaining months: remaining years × 12.
• Hours spent on an activity: daily hours × remaining days.
• Share of your time: hours of the activity ÷ total remaining hours (remaining days × 24).

A worked example step by step

Imagine a 36-year-old person who chooses a life expectancy of 82 years and spends 8 hours a day sleeping and 3.5 hours a day on their phone.

1. Remaining years: 82 − 36 = 46 years.
2. Remaining days: 46 × 365.25 ≈ 16,802 days, that is, about 2,400 weeks or 552 months.
3. Hours of sleep: 8 × 16,802 ≈ 134,400 hours, about 15.3 years of full days.
4. Hours on the phone: 3.5 × 16,802 ≈ 58,800 hours, about 6.7 years of full days.
5. Share of their remaining time: sleeping takes up 33.3% and the phone 14.6% (3.5 ÷ 24).

With the same numbers, that person can see how the figure would change if they spent one hour less on their phone: they would save about 16,800 hours, about 700 full days.

What data we do not use

Sandglass does not ask for or use your sex, your health condition, your lifestyle habits, your name or your exact location. It does not use artificial intelligence models to estimate your longevity, does not call any external database during the calculation and does not store your data. That simplicity is deliberate: the less personal data we need, the lower the risk to your privacy.

How the figures are reviewed and updated

Regional life expectancies are rounded and reviewed periodically from the statistical publications of the United Nations, the WHO and the World Bank. If you spot a figure you think is out of date or a calculation error, you can let us know from the contact page; every notice is reviewed and, where appropriate, corrected.

Other Sandglass tools

Besides the time breakdown, you can use the exact age calculator, the Your life in weeks calendar, the sleep calculator and the screen time calculator.