How accurate are timing systems?

It used to be that sports timing systems were only for dedicated professionals to generate precision race results. Thousands of dollars needed to be invested into that equipment. Today, with everything from apps in the palm of your hand to rental systems that almost anyone can use, it’s more important than ever for NGBs to train their officials to understand the limitations of different systems.

Timing is simple, but it’s not easy.

What do we mean by this? Let’s examine. At its core, timing is math. The first thing that most people don’t realize is that you are working in base 60 and not base 10. So “carrying” time in addition and subtraction is not about carrying a one, it’s about carrying 60. (One minute = 60 seconds.)

Inherent Inaccuracy of Systems

The other thing to consider is that there is error built into every system, so whether you are using a stopwatch, or a $20,000 photo finish camera, the maximum precision of that device should never be used because of the inherent error built into the system. Even if an operator tells you that their system is accurate to the 1/1,000,000,000 of a second – and those systems are out there – it’s important to come up with a protocol for all systems to avoid these inaccuracies and potential podium errors.

How the options were tested:

It took my partner and I almost 10 years to settle on a transponder system. We did not buy into the ‘our system is the best and only one you need to use’, because we had seen several of these systems fail. Weather, power supply issues, networking, and just plain non-functioning equipment, scared the crap out of us. We rented and tested many systems comparing the results of the transponder system with one of the most accurate system that we currently use and is recognized by the sporting industry as the Gold Standard – a high speed, line scan camera.

The variations we found within these systems was staggering. We found that some transponder systems varied by almost a full second based on the placement of the transponder by the athlete.

The critical thing that we found is that placement of the transponder can have a significant effect on the result. Mountain bike plates with passive transponders that are angled give a slower reading that plates that are at a 90-degree angle to the ground. The results varied by almost a full second.

Active transponders that are mounted even a fraction of an inch in a different location on a bicycle can change the outcome of a sprint finish or time trial by almost one half (.5) of a second.

Options to consider when generating results


One of the most common problem that beginners often don’t realize is that spreadsheets often see time as a date. When using these solutions, there is quite a lot of ‘stuff’ that needs to happen in the background to extract hours, minutes, and seconds to generate a final time. And while there are programs out there that do handle this better than others, you are still working in base 60. This makes it important for the official to proof times to make sure precision is correct.


Apps are great, but they have their limitations. Typically, you are working with a button press. And while we’ve seen people that can match an electronic system with the push of a button, these folks are rare. The “usual” maximum precision that we have studied that can be expected from someone pushing a key or a stopwatch is about 1/10th of a second (.1). By the way, if you can garner folks who have been the manual timers at swim meets, these are the people you want as timing volunteers or running your app or keyboard.


Here’s where the rubber starts to hit the road and is what most folks know as ‘chip timing’. Transponders are becoming more and more affordable and more and more accurate, but they still have their limitations. Let’s compare:

Passive transponders for running:

Example: the throw away ones on the back of a bib
These are averaging around 1/10th of a second accuracy. For mass start events, these are just fine. But if you have an elite category in your race, or a measured course where you expect records to be set, you are going to want those athletes wearing active transponders or backing up your finish with an approved photo system.

Passive transponders for cycling: 

These can vary from from 1/10th (.1) of a second to 2/100th (.02) accuracy. They are typically used for mass start events at slower speeds (less then 15mph). Again, fine for mass start events, but not accurate enough for time trial events. What we mean by time trial events are events where the rider is racing against the clock where a measured start time happens such as on the road, a downhill mountain bike race, or an enduro type event.

Active transponders:

There are several of these available and their accuracy is averaging around 1/100th (.01) of a second. These are the ones that you wear on an ankle or attached to a bike frame. They are also more accurate at higher speeds (around 45mph). You might see these more in time trial type events or at multi stage or multi sport events.

Moto transponders:

These are active transponders that work at much higher speeds with higher accuracy. These average around 1/1000 (.001) of a second at speeds averaging up to 150mph. These are typically found in race cars or motorcycles but are finding their way more and more into road bicycling events because of their accuracy.

With transponders, it’s still critical to have some type of back up system. Even something as easy as a person with a clipboard writing numbers down or reading them into their phone or a tape recorder is better than nothing if the elements conspire against you.

Determining result precision.

Based on the above datum, it is becoming critical that NGBs recognize what system limitations are and apply limits to those for scoring purposes. We have seen timing companies who don’t understand the limits of their system, apply a maximum accuracy to their results – even when it is not possible.

Why not use the maximum accuracy of my system?

Quite simply, it’s because it is a man-made system There is enough variance in that last digit that it makes it impossible to accurately use the complete precision of your timing system. So even though sports like ski racing and bob sleigh utilize precision quartz clocks that can time to the 1/10,000 (or better), these sports realize the variability and only time to the 1/100th or 1/1000th as their precision.

Where should we go from here?

Maximum precision of results should be enacted as a fair way to generate results so that event promoters, officials, and especially athletes, know what to expect. This leaves the responsibility of understanding the limits of every system to the the NGB that determines the maximum precision and makes it easier for the folks on the ground. Since we are not recommending a brand, we feel that this is an unbiased and fair recommendation to take into consideration.


• Hand timing: no greater than 1/10th (.1) of a second
• Passive transponders: no greater than 1/100 (.01) of a second. Not recommended for time trial events without an approved photo system
• Active transponders: no greater than 1/100 (.01) of a second. Photo system suggested for mass start events.
• Moto Transponders: no greater than 1/1000 (.001) of a second.
• Line Scan Camera Systems: no greater than 1/1000 (.001) of a second
• Other Camera systems: no greater than 1/100 (.01) of a second
• Photocells at the start and finish: No greater than 1/1000 (.001)
• Photocells at the finish only: No greater than 1/100 (.01) if used at the finish only

Questions or Comments? Go ahead and drop us a line info at cjtiming dot com or give us a call. 970.728.0251. We’ve got 25 years of timing experience from fun runs to the Olympic Games. Check out some of the technology we use HERE.