Family train tickets in Japan aren't complicated once you know the buckets — but the defaults trip people up, and a couple of small mistakes (buying a ticket a toddler didn't need, or reserving a seat that flips a free child to a paid one) quietly cost you. Here's the math, minus the guesswork.
Japan Railways and most private railways use the same age groups. What matters is the child's age (and, for the school-age band, elementary-school status), not their height.
| Age | Japanese term | Train fare |
|---|---|---|
| 0 (under 1) | 乳児 (nyūji) | Free* |
| 1–5 (pre-school) | 幼児 (yōji) | Free* (up to 2 per adult) |
| 6–11 (elementary) | 小児 (shōni) | Half of the adult fare |
| 12 and over | 大人 (otona) | Full adult fare |
*Free for base fare when the child does not occupy their own reserved seat. The half fare for ages 6–11 applies to the base fare, limited-express/Shinkansen surcharges, and seat reservations — each is roughly half the adult amount, rounded per the operator's rules.
This is the one that surprises families. A child under 6 rides free — but that's for riding on a parent's lap or in an unreserved seat. The moment you reserve a dedicated seat for that under-6 (common on the Shinkansen for a long trip), they're treated as a child and you pay the child fare, including the reserved-seat surcharge. There's also a headcount rule: each paying passenger can bring up to two under-6s for free; a third under-6 pays the child (half) fare.
For kids aged 6–11, a child IC card (a "Kodomo" Suica or PASMO) automatically deducts the half fare at the gate — much simpler than buying paper tickets each ride. The catch for visitors: a child IC card usually can't be bought from a machine. You get it at a staffed ticket counter, and you'll need to show the child's passport (age verification). Children under 6 don't need a card at all — they just walk through with you. When the child turns 12, the card must be switched to an adult card.
Multi-day passes have their own child pricing. The nationwide Japan Rail Pass, for example, offers a child pass (ages 6–11) at half the adult price, while under-6s travel free under the same lap/no-reserved-seat rule. Whether a pass beats point-to-point child fares depends on your route — the same break-even math as adults, just halved. Run the JR Pass math →
Don't overbuy for little kids, and don't get caught by the reserved seat. Under-6s are free — so skip the ticket unless you want a guaranteed seat on a long Shinkansen leg (then it's a child fare, by choice). For ages 6–11, grab a child IC card at a staffed counter with their passport and let it charge the half fare automatically. For 12 and up, they're adults in the eyes of the fare table — budget accordingly. The rules are simple; the money leaks come from not knowing them.
Mio