Age Calculator — Years, Months, Days & Next Birthday

Enter your birth date to see exact age, days lived, and countdown to your next birthday—calculated locally in your browser.

Select your date of birth to see your age, next birthday, and more.
By Muhammad Abdullah Rauf · Founder, EverydayTools.proUpdated 2026

What is an age calculator?

An age calculator computes the exact age between two dates — typically a birth date and today — returning years, months, days, and sometimes hours and minutes.

An age calculator determines the precise elapsed time between a birth date (or any start date) and a target date. The calculation correctly handles leap years, varying month lengths (28, 29, 30, 31 days), and the difference between calendar years and elapsed years.

Beyond personal age, age calculators are used to verify eligibility (minimum age for legal purposes), calculate ages as of a historical date, determine how many days until a birthday, and answer questions like 'how old was Person X when Event Y happened?' The tool removes date arithmetic errors that are easy to make manually.

Quick answers

Concise answers for common searches — definitions, steps, and comparisons.

How does an age calculator handle a February 29 birthday in non-leap years?

People born on February 29 (a leap day) have a birthday that only exists in leap years. Age calculators use one of two conventions: (1) The most common convention: treat March 1 as the legal birthday in non-leap years — the person turns N years old on March 1. Many countries' legal systems (UK, Hong Kong, New Zealand) use this rule explicitly. (2) Alternative convention: treat February 28 as the birthday in non-leap years — the person turns N years old on February 28. The difference is one day. For most practical purposes (age verification, eligibility checks), either convention gives the same year count. The legal convention matters for borderline cases like turning 18 or 21.

What is the difference between calendar age and total elapsed days?

Calendar age counts completed years, months, and days since birth using the Gregorian calendar's structure — it advances by one year on each birthday, regardless of how many days that year contains. Total elapsed days is a raw count of all calendar days between birth date and today. The two measures diverge because of leap years: a person born on March 1 in a non-leap year has the same calendar age as someone born on March 1 in a leap year at the same point in time, but their total elapsed day counts differ by 1 for every leap year in between. Calendar age is what people mean by 'how old are you'. Elapsed days is used in medical contexts (gestational age, drug study duration), legal eligibility calculations, and financial day-count conventions (actual/actual).

How do you calculate a historical figure's age at a specific event?

To calculate a historical person's age at a specific event: (1) Enter the birth date in YYYY-MM-DD format. For dates before 1582 (before the Gregorian calendar reform), be aware that the Julian calendar was in use — some dates may differ from the proleptic Gregorian calendar by 10–13 days. (2) Enter the event date as the target date. (3) The result in years, months, and days is the person's age at that moment. Example: Shakespeare (born April 23, 1564) at the first Globe Theatre performance (1599): age 35 years. Note: for dates before year 1 (BCE/BC dates), most calculators use the astronomical year numbering where 1 BC = year 0 — adjust accordingly if the tool requires positive years only.

How to use Age Calculator — Years, Months, Days & Next Birthday

  1. Enter your date of birth

    Select or type your birth date using the date picker. The calculator accepts dates in any standard format (MM/DD/YYYY or YYYY-MM-DD).

  2. Optionally set a target date

    By default the calculator uses today's date. Change the target date to calculate your age on any past or future date — useful for legal or document purposes.

  3. Read your age breakdown

    Results show your age in years, months, days, hours, and minutes. You also see the day of the week you were born and how many days until your next birthday.

  4. Share or copy results

    Use share link or copy formatted age text for forms, messages, or records.

Who uses Age Calculator — Years, Months, Days & Next Birthday?

Common real-world scenarios where this tool saves time.

Document and form completion

Quickly verify your exact age in years and days for government forms, visa applications, insurance documents, and legal contracts that require a precise age.

Medical age requirements

Check whether a patient or individual meets minimum age thresholds for medical procedures, clinical trials, or age-restricted medications.

Retirement and milestone planning

Calculate exactly how many years, months, and days remain until you reach a milestone age — 65 for retirement, 25 for car insurance discounts, or 18 for legal adulthood.

Genealogy and historical research

Determine the age of a historical figure at a specific date — useful for family history research, academic papers, and biography writing.

Age Calculator — Years, Months, Days & Next Birthday examples

Personal age calculation

Input

Birth date: March 15, 1990 · Target date: May 2, 2026

Output

Age: 36 years, 1 month, 17 days · Total days lived: 13,197

The calculator counts full years first (36), then remaining months (1), then remaining days (17) after the last monthly anniversary. The leap year in 2000, 2004, etc. adds a day to the total day count.

Legal age verification

Input

Birth date: May 3, 2008 · Target date: May 2, 2026

Output

Age: 17 years, 11 months, 29 days — not yet 18

The 18th birthday is May 3, 2026. On May 2, the person is still 17 years old — one day short of the threshold. Useful for precise eligibility checks where exact date matters.

Historical age research

Input

Birth date: April 15, 1452 (Leonardo da Vinci) · Target date: August 2, 1519

Output

Age at death: 67 years, 3 months, 17 days

Age calculators work for any historical dates, not just modern ones — useful for biographical research, genealogy, and historical writing.

Reference tables

Calendar age vs total days lived

MeasureWhat it showsTypical use
Years, months, daysCalendar age since last birthdayHow old am I?
Total days livedRaw day count including leap daysMedical or research contexts
Next birthday countdownDays until upcoming birthdayPlanning and milestones

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Frequently Asked Questions

How does the age calculator work?

The calculator subtracts your birth date from today's date (or any date you choose) and returns the precise difference in years, months, and days. It accounts for leap years and varying month lengths — for example, February and months with 30 days are handled correctly.

Why does my age show differently than I expected?

If your birthday hasn't occurred yet this calendar year, the calculator shows your current age (one year less than the upcoming year). For example, if today is March 1 and your birthday is April 15, the calculator shows your age as of the previous April 15.

Can I calculate age in months and days?

Yes. The calculator breaks down your age into years, months, and remaining days. For example, if you are 30 years and 4 months old, it shows 30 years, 4 months, and the exact number of days since your last birthday.

Can I use this to check if someone is 18?

Yes. Enter the birth date and today's date. The calculator shows the exact age in years — if it shows 18 or more, the person has reached legal adulthood (in most countries). For precise eligibility checks, verify the birthday has passed today.

Is my date of birth uploaded?

No. Age math runs locally in your browser. Your birth date and target date are not sent to EverydayTools servers.

Privacy, accuracy, and trust

Privacy

Date of birth and target dates are processed in your browser—they are not uploaded to EverydayTools servers.

Accuracy

Uses Gregorian calendar rules including leap years; Feb 29 conventions may follow local legal rules.

For personal and planning use—not legal, medical, or official identity verification.

Part of Date & Time Tools

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Reviewed by EverydayTools Editorial Team on 2026-05-20.