Is a race timing chip an NFC tag?
No, although both are RFID. Timing has to read hundreds of tags at several metres while people run past without cooperating, which is what UHF RFID exists for. NFC couples over centimetres and reads one tag at a time, deliberately, which is the opposite requirement.
What timing has to do
A field crosses a mat several abreast, at speed, and every one of them has to be recorded to the second. Nobody stops, nobody presents anything, and nobody is aiming at a reader.
The tag is in a bib or on a shoe, at whatever height and angle the runner happens to be, and the mat has to catch it from a metre or more away while several others are in range at the same instant.
That is the specification, and it is what decides the technology before anyone thinks about cost.
Why NFC cannot do it
Range. NFC works by magnetic coupling at 13.56 MHz, which exists only over a few centimetres, as the frequency page and the range page both set out. A runner would have to brush the reader.
One at a time. A phone or a reader that finds two tags in its field selects one and rejects the rest, which the anticollision page explains and the two tags page demonstrates. A finish line is nothing but collisions.
Deliberateness. NFC is designed around a person choosing to present something, which is a feature everywhere else on this site and a disqualification here.
UHF RFID was built for the opposite case, many tags at metres in a sweep, which the UHF comparison covers for inventory and which timing uses for the same reason.
Both are RFID, hence the confusion
RFID is a family of technologies across several frequency bands, and NFC is one corner of it, which the comparison page untangles. Calling both of them chips hides a difference of two orders of magnitude in range.
The practical consequence is the question people actually arrive with: a phone will not read a race bib tag, ever, because phones have no UHF radio. Nothing is broken and no application will fix it.
The same applies in reverse. A timing mat will not see an NFC tag in a pocket, which is worth knowing before anyone tries to improvise a checkpoint with stickers.
Where NFC does appear at a race
At the registration desk and the bib collection, where a card or a wristband identifies a person who is standing still, which is the event badge case exactly.
At the expo, on stands and product displays, where a visitor taps because they want to.
And after the finish, where a finisher's medal, a bib or a card can carry an address to the results page, a photograph or a certificate, since that tap is deliberate and happens at rest.
What all three have in common is a person who chose to present something. That is the line between the two technologies, and it holds everywhere.
Frequently asked questions
Can my phone read my race chip?
No. Timing tags are UHF and phones have no UHF radio, so there is nothing for the phone to talk to. It is not a setting or an application.
Are timing chips and NFC tags both RFID?
Yes, which is the source of the confusion. They sit in different frequency bands with ranges two orders of magnitude apart.
Could a small race be timed with NFC?
Only by making each runner stop and present a tag, which is a queue rather than a timing system.
Why do some chips get returned and others not?
That is a choice of system: some use a disposable tag in the bib, others a reusable transponder collected at the finish.