Kazoedoshi (数え年): Japan's Traditional Age Counting Explained

Definition

Kazoedoshi (数え年 かぞえどし) is a traditional Japanese age system where:

1. You are counted as 1 at birth, and
2. You add one year on New Year’s Day (Jan 1)

In modern Japan, the standard “official” age used in legal and administrative contexts is mannenrei (満年齢 まんねんれい, full age)—the age that increases on your birthday.

Key Points

1) Kazoedoshi vs Mannenrei: the core difference

That is why kazoedoshi is usually 1–2 years higher than full age.

2) The simplest way to calculate kazoedoshi (fast)

Two practical methods are widely used (including by shrines):

Method A (by birth year):

Kazoedoshi = current year − birth year + 1

This follows directly from the “1 at birth + 1 each New Year” rule.

Method B (from your full age):

3) Why kazoedoshi still appears in Japan today

Even though modern society typically uses full age, kazoedoshi remains common in traditional rites of passage, especially:

• Yakudoshi (厄年): ages are “usually counted by kazoedoshi”
• Shichi-Go-San (七五三): traditionally celebrated by kazoedoshi, though many families now use full age

A helpful mental model: kazoedoshi fits traditions that treat “age” as a year-based milestone, not a birthday-based milestone—so people born in the same year “move together” at New Year.

Comparison

Quick table: which age system should you use?

Timeline example (why people get confused)

If someone is born Dec 31, kazoedoshi jumps quickly:

This looks strange if you only know full age—but it matches the “New Year milestone” logic.

Practical Examples

Example 1: “What is my kazoedoshi in 2026?”

If you were born in 1990:

2026 − 1990 + 1 = 37 → kazoedoshi is 37 in 2026

If you only know your full age:

• Birthday already passed this year → full age + 1
• Birthday not yet passed → full age + 2

Example 2: Why this matters for yakudoshi (厄年)

Shrine guidance explains that yakudoshi ages are usually counted by kazoedoshi and lists common ages:

So if a shrine asks your yakudoshi, they may expect your kazoedoshi, not your passport age.

Also, because kazoedoshi “updates” at New Year, people often do yakubarai (厄祓い) around the time the age changes.

Example 3: Shichi-Go-San (七五三)

Shichi-Go-San celebrates children at ages 3, 5, 7, traditionally on Nov 15.

• “Originally it is by kazoedoshi, but now it is often done by full age.”

Practical tip for parents:

• If your child is small/young for their cohort, using full age can be more comfortable
• If you want to align with the “same birth-year cohort” concept, use kazoedoshi
• When in doubt: check the shrine/temple’s FAQ or ask directly

Why Japan moved to full age (but kept kazoedoshi in tradition)

After 1950, a law recommending full age contributed to full age becoming the norm. In legal contexts, “age” means full age.

At the same time, shrine practice and traditional rites still use kazoedoshi—explicitly so for yakudoshi.

The result is a practical split:

Copy/Paste Templates

Short explanation (for a non-Japanese friend)

“In Japan there’s a traditional age system called kazoedoshi. You’re counted as 1 at birth and you add a year on New Year’s Day. It’s still used for traditions like yakudoshi and sometimes Shichi-Go-San.”

Clarifying question (when a form/event says “age”)

“Do you mean full age (mannenrei) or traditional age (kazoedoshi)?”

Website-friendly notation block

• 数え年（かぞえどし, kazoedoshi）: 1 at birth, +1 on Jan 1
• 満年齢（まんねんれい, mannenrei）: age that increases on your birthday

Glossary

Related Pages

• Unlucky Ages (Yakudoshi)
• Shichi-Go-San (七五三)
• Chinese Zodiac (Eto)
• Japanese Era Names (Gengō)
• Fiscal Year (Nendo)
• Age Reference Chart