🎂Age Calculator
Calculate a person's exact age in calendar years, months and days from their date of birth, plus total days lived. Reference date defaults to today (UTC).
Worked examples
Born 1990-06-15, age at 2026-09-01
GET /api/v1/calculators/age-calculator?birth=1990-06-15&on=2026-09-01
Result: 36 years, 2 months, 17 days
Born 2000-02-29 (leap), age at 2026-09-01
GET /api/v1/calculators/age-calculator?birth=2000-02-29&on=2026-09-01
Result: 26 years, 6 months, 3 days
Born 1975-11-30, age at 2026-01-01
GET /api/v1/calculators/age-calculator?birth=1975-11-30&on=2026-01-01
Result: 50 years, 1 months, 2 days
Machine API (x402)
$0.001 / callThis tool is also a JSON API for AI agents. Requests without payment receive 402 Payment Required plus instructions; agents pay USDC on Base via the x402 protocol — no accounts, no API keys.
GET /api/v1/calculators/age-calculator?birth=1990-06-15&on=2026-09-01 HTTP/1.1
Host: agenttools-hub.vercel.app
→ 402 (payment required, instructions in headers)
→ 200 (after X-PAYMENT header; JSON body below)
{
"tool": "calculators/age-calculator",
"input": {"birth":"1990-06-15","on":"2026-09-01"},
"result": { "value": 36, "answer": "36 years, 2 months, 17 days" }
}Agent docs: /llms.txt · OpenAPI spec · integration guide
About this tool
Enter a date of birth to get the exact age in calendar years, months and days, total days and weeks lived, and a countdown to the next birthday. Omit the reference date to use today (UTC).
age = full calendar years, then remaining months, then remaining days between birth and reference date
Frequently asked questions
How does a Feb 29 birthday count?
Feb 29 birthdays advance to Mar 1 in non-leap years for 'days since' counting; the calendar year count still increments on Mar 1.
Which time zone is used?
Both dates are treated as midnight UTC, so the age is the same no matter where the request comes from.