Can a watch or a ring replace the phone at a terminal?
Both can carry a credential, and what separates them is whether the object can say anything about who is wearing it. A watch is unlocked once and knows it has stayed on the wrist; a passive ring has no sensor, no screen and no way to ask, so it behaves like a piece of plastic.
What the object can verify
The reason a phone is treated differently from a card is that it checks who is holding it before it presents anything, which the limits page explains is the missing step contactless ceilings compensate for.
Every wearable sits somewhere on that line. The question is never how the object looks or what it costs, it is what it can establish about its wearer at the moment of the tap.
Answer that and the rest follows: what it may be allowed to spend, whether a terminal asks for anything else, and what happens when it is lost.
What a watch actually does
A watch is unlocked once, when it is put on, and it can detect that it has stayed on the wrist since. That continuity is what stands in for a check at each payment, and it is why a watch is usually treated like a phone rather than like a card.
Take it off and the chain is broken: the watch locks and has to be unlocked again before it will present anything. That behaviour is the security property, and it is also the source of the familiar annoyance of a watch asking for a code after it was removed for a minute.
It carries its own credential, as the two cards page sets out, so it is revoked on its own and appears on its own in an account.
A ring is closer to a card
A passive ring, of the kind the wearables page describes, has no battery, no sensor and no way to know whose finger it is on. It presents what it holds to any reader that powers it.
That is the property of a card, and it brings the consequences of a card: the ceilings exist for it, the issuer decides whether to allow it at all, and a lost ring is a lost card rather than a locked device.
It also cannot tell you anything. No screen, no confirmation, no way to see which credential it holds or whether a payment went through, which the contents page makes plain for every passive object.
None of that makes a ring a bad object. It makes it a card in a different shape, and the decision should be taken on that basis rather than on the assumption that a wearable behaves like a phone.
Choosing between them
For paying, a watch replaces a phone in practice and a ring replaces a card. That is the whole comparison, and everything else follows from it.
For access and transit, the same question applies with different stakes: an object that cannot verify its wearer is a token that anybody holding it can use, which the credential page takes up for badges.
And for anything carried all day, the hardware constraints in the wearables page matter as much as the credential: a small antenna at an awkward angle is a tap that needs two attempts, which is a worse experience than the card it replaced.
Frequently asked questions
Why does a watch not ask for a code every time?
It was unlocked when it was put on and can tell it has stayed on the wrist. Taking it off breaks that and it locks again.
Can a payment ring be used by someone else?
A passive ring presents what it holds to any reader that powers it, so it behaves like a card. That is why the usual contactless ceilings apply to it.
Do wearables have their own credential?
Yes. Each device is provisioned separately, so it appears separately on an account and is revoked on its own.
Is a wearable as reliable as a phone at a terminal?
The antenna is smaller and the angle is often awkward, so expect more second attempts than with a phone or a card.