Age Calculator

About Age Calculator

How Age Calculation Works

Calculating age sounds simple, but calendars are surprisingly tricky. Months have different lengths (28, 29, 30, or 31 days), leap years add an extra day every four years (mostly), and the rules for "how old are you" differ across cultures.

This calculator uses the most common Western convention:

1. Count the complete years from your birth date to today
2. Count the remaining complete months
3. Count the remaining days

Example: If you were born on 15 March 1990 and today is 6 April 2026, your age is 36 years, 0 months, and 22 days. The total days lived would be approximately 13,171 days.

The calculator correctly handles leap years. A leap year occurs every 4 years, except for years divisible by 100, unless also divisible by 400. So 2000 was a leap year, but 1900 was not. The next exception won't matter until 2100.

Your Life in Numbers

Beyond years and months, the calculator shows some interesting statistics about your time alive:

Age	Days Lived	Weeks Lived	Hours Lived
1 year	365	52	8,760
10 years	3,652	521	87,648
18 years	6,574	939	157,776
25 years	9,131	1,304	219,144
30 years	10,957	1,565	262,968
40 years	14,610	2,087	350,640
50 years	18,262	2,608	438,288
65 years	23,741	3,391	569,784
80 years	29,220	4,174	701,280

A popular personal milestone is reaching 10,000 days alive, which happens at about age 27 years and 4 months. Some people celebrate their 1,000-week birthday (around age 19 years and 2 months) or track round numbers of days as personal markers.

When Does Age Matter Legally?

Age thresholds are used for all sorts of legal and practical purposes. Here are some common ones:

Age	UK Milestone	US Milestone
5	Compulsory school age	Kindergarten entry (varies by state)
16	Can leave school, consent to medical treatment	Can drive in most states
17	Can learn to drive a car	-
18	Legal adult, can vote, drink alcohol, get a tattoo	Legal adult, can vote, join military
21	-	Can drink alcohol
25	Car insurance typically drops	Can rent a car without surcharge
55	Can access pension (minimum pension age rising to 57 in 2028)	Can withdraw from 401(k) early (with penalty)
59.5	-	Can withdraw from 401(k) penalty-free
66	State Pension age (rising to 67 by 2028)	Full Social Security retirement age (67 for those born after 1960)

Age Calculation Across Cultures

Not everyone counts age the same way. In the traditional Korean system, a baby is 1 year old at birth and gains a year every 1 January. This means a baby born on 31 December would be considered 2 years old the very next day. South Korea officially switched to the international age system for legal and administrative purposes in June 2023, but the traditional counting is still used socially.

In China, the traditional age counting (xu sui) is similar. A child is 1 at birth and gains a year at Chinese New Year. The international system (shi sui) is used for official purposes.

Fun Age Facts

• The average life expectancy in the UK is about 81 years (79 for men, 83 for women), according to the ONS. That is roughly 29,500 days.
• If you are 30, you have already lived through about 37% of your expected lifespan.
• The oldest verified person ever was Jeanne Calment of France, who lived to 122 years and 164 days (44,724 days).
• Your "golden birthday" is when your age matches the day of the month you were born (turning 15 on the 15th).
• People born on 29 February technically only have a birthday every four years. They are sometimes called "leaplings."

Age in Different Calendar Systems

The Gregorian calendar is not the only system in active use. If you deal with international dates, these are the major alternatives:

Calendar	Year Length	Used By	Current Year (approx.)	Age Difference from Gregorian
Gregorian	365.2425 days	Most of the world	2026	Baseline
Islamic (Hijri)	354.37 days (lunar)	Saudi Arabia, Iran (partially), religious dates worldwide	1447-1448 AH	~3% more years (a 30-year-old in Gregorian is ~31 in Hijri years)
Hebrew	353-385 days (lunisolar)	Israel (alongside Gregorian), Jewish religious observance	5786-5787	Nearly identical to Gregorian over a lifetime
Ethiopian	365.25 days	Ethiopia, Eritrea	2018-2019 EC	Same year length, but 7-8 years behind Gregorian
Thai Solar	365.2425 days	Thailand (official)	2569 BE	Same year length, 543 years ahead of Gregorian

The practical impact: someone born on 1 January 1990 is 36 years old in Gregorian years (as of 2026) but about 37 in Hijri years, because the Islamic lunar year is roughly 11 days shorter than the solar year. Over a lifetime, this gap widens. A person who has lived 70 Gregorian years has lived about 72 Hijri years.

Biological Age vs Chronological Age

Your chronological age is the one on your birth certificate. Your biological age reflects how your body is actually ageing, and the two do not always match.

Research from the Dunedin Study (a longitudinal study of 1,037 people born in Dunedin, New Zealand in 1972-73, published in PNAS by Belsky et al. in 2015) found that by age 38, participants had biological ages ranging from 28 to 61. Some people were ageing nearly three years for every chronological year, while others were ageing slower than average.

Factors that accelerate biological ageing (supported by peer-reviewed research):

• Smoking: Adds roughly 4-10 years of biological age. The British Medical Journal reports smokers lose an average of 10 years of life expectancy.
• Chronic stress and poor sleep: Telomere shortening is accelerated by chronic stress (Epel et al., PNAS 2004).
• Sedentary lifestyle: The WHO estimates physical inactivity contributes to 3.2 million deaths per year globally.
• Heavy alcohol use: More than 14 units per week (UK Chief Medical Officers' guideline) is associated with faster ageing markers.

Biological age testing is still an emerging science. Epigenetic clocks (like GrimAge and PhenoAge, developed by Steve Horvath and Morgan Levine respectively) measure DNA methylation patterns and are currently the most validated approach. Commercial tests are available but vary in accuracy.

Retirement Age by Country

State pension ages vary widely and many countries are raising them as life expectancy increases:

Country	Current State Pension Age	Planned Changes	Source
United Kingdom	66	Rising to 67 by 2028, then 68 between 2044-2046	gov.uk
United States	67 (born 1960+)	66-67 depending on birth year. No current legislation to increase further.	ssa.gov
Germany	66 (rising)	Rising gradually to 67 by 2031	Deutsche Rentenversicherung
France	64 (from Sep 2023)	Raised from 62 to 64 under the 2023 pension reform	service-public.fr
Japan	65	Employers must offer employment until 70 (since April 2021)	Ministry of Health, Labour and Welfare
Australia	67	Reached 67 on 1 July 2023. No further increases legislated.	Services Australia
Canada	65	Can take CPP early at 60 (reduced) or delay to 70 (increased)	canada.ca
Italy	67	Linked to life expectancy changes	INPS
Netherlands	67	Linked to life expectancy from 2025	SVB
South Korea	63 (rising)	Rising to 65 by 2033	National Pension Service

The trend is clear: retirement ages are going up almost everywhere. Planning for retirement earlier gives you more flexibility. The retirement calculator estimates how much you need to save based on your target age.

Life Expectancy by Current Age

Life expectancy at birth is the headline figure (81 years in the UK per ONS, 78.4 in the US per CDC NCHS (2023 data)), but your life expectancy actually increases the longer you have already lived. This is because you have already survived the risks of childhood, accidents, and early disease. The data below is from the UK ONS National Life Tables (2020-2022) and US Social Security Administration (SSA) actuarial tables (2023):

Current Age	UK Male - Expected Additional Years	UK Female - Expected Additional Years	US Male - Expected Additional Years	US Female - Expected Additional Years
30	49.5	53.1	47.6	52.2
40	39.9	43.3	38.3	42.7
50	30.7	33.8	29.3	33.3
60	22.1	24.8	21.2	24.4
65	18.4	20.9	17.5	20.3
70	14.9	17.1	14.1	16.5
80	8.8	10.1	8.3	9.8
90	4.4	4.9	4.1	4.7

Notice that a 65-year-old UK male is expected to live to 83.4 (65 + 18.4), not 79. The at-birth figure of 79 includes people who died young. If you have made it to 65, your expected lifespan is longer than the headline number suggests. This matters a lot for pension and savings planning.

Key Age Milestones for Insurance and Legal Purposes

Beyond the basic legal ages, there are several practical thresholds that affect your finances and daily life:

Age	What Changes	Where
17	Can apply for a provisional driving licence	UK
25	Car insurance premiums typically drop significantly (end of "young driver" risk band)	UK and US
25	Can rent a car without a "young renter" surcharge ($10-30/day extra)	US (most companies)
26	Removed from parents' health insurance plan (ACA provision)	US
40	Life insurance premiums start increasing more steeply	UK and US
50	AARP membership eligible, 401(k) catch-up contributions ($7,500 extra/year)	US
55	Can access private pension without unauthorised payment tax charge (rising to 57 in 2028)	UK
60	Free prescriptions	England
62	Earliest age for Social Security retirement benefits (at reduced rate)	US
65	Medicare eligibility begins	US
66	State Pension age (rising to 67 by 2028)	UK
75	Car insurance premiums often increase again	UK and US

Need to find the exact number of days between two specific dates? Use the date difference calculator. For counting down to events, try the countdown timer. If you are checking age for health purposes, the BMI calculator uses age as one of its context factors. Planning for retirement? The retirement calculator estimates the savings you need based on your target retirement age.

Your date of birth is never sent anywhere. All calculations happen locally in your browser.

Sources

• ONS - National Life Tables, UK (2020-2022)
• CDC NCHS - US Life Expectancy 2023
• SSA Actuarial Life Table
• GOV.UK - State Pension Age
• PNAS - Belsky et al. 2015 (Dunedin Study on Biological Ageing)
• WHO - Physical Activity Fact Sheet