Guide
Race timing accuracy: RFID, photocells or manual timing and the errors to expect
· 6 min read
In short
- Resolution—how many decimal places a time displays—is not the same as accuracy, which describes how closely the recorded time matches the actual moment.
- Manual timing depends on human reaction time. For track records in events up to 800 metres, athletics therefore requires fully automatic timing; statistical comparisons between hand and automatic times use conversions of approximately 0.14 to 0.24 seconds.
- Standard UHF RFID chips are suitable for results recorded in whole seconds. The antenna detects a chip within a zone, not at the exact moment it crosses the line.
- Photocells, decoders, touchpads and photo-finish systems can measure to hundredths, thousandths and beyond, but they are more expensive and require experienced operators.
When someone says that a timing system is accurate to one hundredth of a second, several different concepts are often being mixed together. Separating them will help you choose the right technology.
Resolution and accuracy
Resolution indicates how many decimal places are displayed. Accuracy describes how closely the displayed time matches the actual moment. A stopwatch showing hundredths is accurate only to about tenths when operated by a person. A decoder displaying thousandths can produce meaningless data if its clock is set incorrectly. Accuracy must therefore be assessed across the entire chain: the sensor, device, clock and procedure.
Manual timing
A person presses the button only after registering the event, which takes a fraction of a second. Athletics accounts for this effect: hand times are stated in tenths and are typically faster than automatic times in sprints, which is why only fully automatic timing is accepted for records. We discuss the conversion in Athletics: false starts and manual timing. Manual timing is acceptable for races timed in whole seconds if the operators can keep up with finishers.
RFID chips
An antenna detects a chip when it enters its reading zone, which may extend for several metres. The software estimates the crossing time from multiple reads. Its accuracy is therefore suitable for whole-second results and crowded finishes, but not for hundredths. How an RFID chip works in running races explains how RFID performs during a race.
Photocells and decoders
A light beam or loop records the moment it is broken or crossed. These devices achieve accuracy measured in hundredths or thousandths of a second and are used in motorsport and skiing; swimming uses touchpads. They are more expensive and require experienced operators, as described in How Formula 1 timing works and Timing in enduro.
Photo finish
A camera records a narrow strip of the finish line as many as 10,000 times per second. It is the most reliable way to decide close finishes, but it is used mainly at elite events. We described the technology’s story in Photo finishes in horse racing.
Errors often come down to preparation and operation
Across all technologies, common causes of errors include incorrect clocks, poorly positioned chips, missing backups and incorrectly assigned bib numbers. See The most common race timing mistakes for an overview.
What this means in practice
Choose the required accuracy according to the rules of the discipline, not simply according to what is technically possible. For most running and cycling events, RFID or well-managed manual timing to whole seconds—as used by TAQIO—is sufficient. Official competitions with close finishes require certified automatic timing.
Frequently asked questions
What is the difference between race timing resolution and accuracy?
Resolution is the level of detail displayed, such as thousandths of a second. Accuracy is the deviation from the actual moment. A device may display thousandths yet still be inaccurate if it is configured or synchronized incorrectly.
How accurate is manual timing?
Times are recorded to tenths of a second and depend on the timekeepers’ reactions. In sprints, a hand time is typically faster than a fully automatic time, so a conversion of approximately 0.14 to 0.24 seconds is used for statistical comparisons. Manual timing is therefore not used to ratify records in track events.
Is RFID accurate to hundredths of a second?
Standard UHF RFID is not designed for hundredths. It is suitable for whole-second results and crowded finishes because the antenna detects the chip within a zone rather than precisely on the line. Hundredths require a system prescribed for the discipline, such as photocells, a photo finish, touchpads or professional decoders.
When is whole-second accuracy sufficient?
At mass-participation running races, cycling marathons and most amateur events. The published time is given in whole seconds, while close finish-line sprints are decided using a finish-line recording.