Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchPC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Some links on this page are affiliate links: if you buy through them we may earn a commission, at no extra cost to you.
A tachymeter bezel is a numbered scale used with a chronograph seconds hand to convert elapsed time into an approximate hourly rate. Time how long a moving object takes to cover a known distance—normally one kilometer or one mile—and the hand points to the speed in kilometers per hour or miles per hour. The same scale can work backward to estimate distance at a constant speed, or measure how many identical tasks can be completed in an hour.
The scale is normally calibrated for events lasting 60 seconds or less. It may be printed on a fixed outer bezel, an inner ring, or the edge of the dial; despite the name, it is not necessarily a rotating bezel. Correct distance markers, accurate start-and-stop timing, and a functioning chronograph determine how useful the result is.
As an Amazon Associate I earn from qualifying purchases.
What does a tachymeter bezel measure?
A tachymeter measures a rate, expressed as units per hour, by using the relationship between elapsed time and a known distance or repeated output. On a conventional watch, the scale is synchronized with the chronograph’s seconds hand. If one kilometer takes 30 seconds, the hand aligns with 120, meaning approximately 120 kilometers per hour. If one mile takes 30 seconds, the same reading means approximately 120 miles per hour.
The distance unit sets the output unit. Timex explains that a tachymeter can express miles per hour, knots, or kilometers per hour; the unit you use for the timed distance determines the corresponding hourly unit. A scale does not identify the unit by itself, so check the watch’s markings and use one consistent distance system.
Popular on Amazon
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
What the printed numbers mean
The numbers are not minutes or seconds. They are hourly-rate values calculated from the time needed to cover one distance unit. Higher numbers appear near the shorter-time end of the scale because a faster event covers the distance in fewer seconds. Lower numbers correspond to slower events and are reached later by the seconds hand.
How do you use a tachymeter to measure speed?
Use a measured course and the chronograph together. The ordinary scale is intended for a single event completed in 60 seconds or less.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →- Choose two markers. Set the start and finish exactly one kilometer or one mile apart, depending on the unit you want to report. A surveyed road, track marker, or other known-distance course is preferable to an estimate.
- Reset the chronograph. Press the reset control so the chronograph seconds hand returns to zero. Identify which hand is the chronograph hand; a small running-seconds hand is often separate from it.
- Start at the first marker. Press the start/pusher as the moving object crosses the first marker. Begin timing as consistently as possible with the chosen reference point.
- Stop at the second marker. Press the stop control when the same reference point crosses the finish marker. Do not stop at a convenient visual point after the object has passed.
- Read the scale. Find the tachymeter number aligned with the chronograph seconds hand. That number is the approximate hourly speed for the distance unit you timed.
Casio describes this method as timing, within 60 seconds, the time needed to cover one kilometer and then using the result to determine approximate average hourly speed. For example, 30 seconds over one kilometer produces a reading of 120, or approximately 120 km/h. Citizen’s official example uses 45 seconds over one kilometer and gives approximately 80 kph (50 mph). TAG Heuer’s guide, published November 28, 2023, gives the equivalent one-mile example: 30 seconds for one mile produces approximately 120 mph.
What if the event takes less than 15 seconds?
Many tachymeter scales become crowded or difficult to read at very short intervals, even though the mathematical rate is higher. Read the closest graduation available and treat the result as approximate. For a very fast event, a longer measured distance can produce an easier-to-read time, then you can adjust the result for that distance.
How do you adjust a tachymeter reading for a different distance?
The printed scale assumes one distance unit. Multiply or divide the reading in proportion to the actual distance, provided the complete event still falls within the scale’s timing range.
Also popular on Amazon
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Use hourly rate = tachymeter reading × actual distance in scale units. Thus, a two-kilometer course doubles the one-kilometer reading, while 500 meters (half a kilometer) halves it. Timex gives a 1.2-mile example: a reading of 80 becomes 96 mph, calculated as 80 × 1.2, when the course is completed within the timing range.
Recommended Free Tools
| Timed distance | Chronograph time | Scale reading | Adjusted result |
|---|---|---|---|
| 1 kilometer | 30 seconds | 120 | Approximately 120 km/h |
| 1 kilometer | 45 seconds | About 80 | Approximately 80 km/h (about 50 mph) |
| 1.2 miles | Time corresponding to 80 | 80 | 96 mph (80 × 1.2), Timex example |
| 2 kilometers | Any reading within range | For example, 60 | 120 km/h (60 × 2) |
| 500 meters | Any reading within range | For example, 120 | 60 km/h (120 × 0.5) |
Do not mix units during the adjustment. A reading taken over one kilometer cannot be relabeled as miles per hour without converting the distance and applying the conversion separately.
Can a tachymeter measure distance?
Yes, but only when the object’s speed is constant and known. This is the reverse-tachymeter method documented by Garmin and Timex. Instead of timing a known distance, you use the known speed to identify when one distance unit has passed.
- Establish a steady speed in the same unit system as the scale, such as 60 km/h on a kilometer-calibrated scale.
- Start the chronograph as the object reaches the reference point.
- Stop when the chronograph seconds hand reaches the number matching the speed—in this example, 60.
- The elapsed sweep represents one kilometer. At 60 km/h, the hand reaches 60 after one minute, so the distance is one kilometer.
The method is sensitive to speed changes. Acceleration, braking, hills, traffic, or an imprecise speed indication make the distance estimate less reliable. It is a practical approximation, not a substitute for surveying equipment or a calibrated distance meter.
How can a tachymeter measure production rate?
A tachymeter can time repeated, identical work rather than travel. Start when one unit begins, stop when it is complete, and read the scale as units per hour. Orient’s manual describes this use and limits the measurement to one minute or less.
Also popular on Amazon
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
For example, if one item takes 30 seconds, the scale reads 120 units per hour. That result assumes every unit takes roughly the same time and that setup, pauses, rejects, and changeovers are not included in the timed cycle. If those factors matter, a longer observation and separate calculation will give a more realistic production rate than a single tachymeter reading.
Why is the tachymeter limited to 60 seconds?
The normal scale is mathematically tied to a one-hour rate and a one-unit distance. A one-unit event lasting more than 60 seconds would place the chronograph hand beyond the useful part of a standard scale. Orient’s manual states, “The measurement time of the tachymeter is 1 minute or less,” and notes that an average speed or hourly production rate cannot be read when the measurement exceeds one minute.
If your event is slower, measure a longer distance so the event finishes within 60 seconds, then multiply the reading by that longer distance in scale units. If no practical distance adjustment is possible, use the chronograph to record the full time and calculate the rate with a calculator instead of forcing a tachymeter reading.
Where is a tachymeter scale placed on a watch?
Manufacturers use several layouts:
- Fixed outer bezel: The numbers surround the crystal and are usually easiest to see while operating the pushers.
- Inner bezel or flange: The scale sits inside the crystal, protecting it from knocks but sometimes reducing contrast or usable space.
- Dial-edge scale: The markings are printed around the dial perimeter and may share space with minute or telemeter markings.
These layouts are fixed scales unless the manufacturer specifically provides a rotating bezel. A rotating dive bezel and a fixed tachymeter scale serve different purposes; turning a non-rotating scale will not change the chronograph calculation.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
What should you compare when choosing a tachymeter chronograph?
The scale itself is only one part of a useful watch. Compare the following features rather than assuming every numbered bezel works identically.
Also popular on Amazon
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Widely Compatible: Transform any USB-C port into a USB-A port and USB-A port into a USB-C port, and connect up a wide range of USB-C(including MacBook, iPad Pro/Air/Mini, iPhone models with USB C ports, Samsung Galaxy series, and Google Pixel series. ) and USB A devices(including external hard drives, phones, mice, printers, and more)
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
| Comparison point | Why it matters | Questions to ask |
|---|---|---|
| Scale placement | Determines viewing angle, glare, and protection. | Is it on the outer bezel, inner ring, or dial edge? Can you read it while pressing the pushers? |
| Legibility | Closely spaced numbers can make short-time readings difficult. | Are the numerals high contrast? Are graduations visible between major numbers? |
| Chronograph layout | You must identify the timing hand and operate start, stop, and reset controls accurately. | Are the pushers distinct? Is the chronograph seconds hand clearly separated from running seconds? |
| Unit system | The distance unit determines whether the result is km/h, mph, knots, or another rate. | Does the printed scale or manual specify the intended unit? |
| Timing range | Standard tachymeters are useful for events up to 60 seconds. | Does the manual state a different range or provide a special scale? |
| Design purpose | Some watches include the scale mainly for motorsport styling. | Is the scale practical to read, or primarily a historical or racing-inspired design element? |
TAG Heuer describes the tachymeter’s historical association with aviation and racing. That heritage explains its frequent appearance on sport chronographs, but a racing-inspired design does not guarantee better measurement visibility or timing precision.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What can make a tachymeter result inaccurate?
Official guides describe the result as approximate and do not establish one universal accuracy tolerance. The main sources of error are procedural:
- Distance error: If the markers are not exactly one unit apart, the calculated rate is proportionally wrong.
- Reaction time: Delays when pressing start or stop add or remove seconds, especially over short events.
- Hand identification: Reading the small running-seconds hand instead of the chronograph hand produces a meaningless value.
- Scale resolution: The hand may fall between graduations, so interpolation is an estimate.
- Changing speed: The result is an average over the timed section, not the instantaneous speed at every point.
- Chronograph operation: A hand that does not reset to zero, a pusher that fails to start or stop, or a movement that is not running properly invalidates the reading.
For a repeatable result, mark the course carefully, use the same reference point on the moving object, and repeat the timing when conditions permit. Report the result as approximate and include the distance and unit used.
What does a tachymeter bezel not tell you?
It does not provide a direct digital speed display, store a route, compensate for acceleration, or establish a legally certified measurement. It also cannot produce a valid reading for an event longer than the scale’s stated range without changing the setup. The number is a rate derived from one timed interval, so it should not be treated as a precision instrument reading.
How do you troubleshoot a tachymeter reading?
The hand does not return to zero
Do not use the reading. Reset the chronograph according to the watch manual; if the hand remains offset, the movement may require adjustment by an authorized service professional.
Also popular on Amazon
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
The event lasts more than one minute
Measure a longer known distance so the interval falls within 60 seconds, then multiply by the distance factor. Otherwise record the elapsed time and calculate the rate directly.
The scale number is hard to read
Improve the viewing angle and lighting, and identify the exact graduation before stopping the chronograph. If the scale is persistently obscured by glare or crowded printing, use the chronograph time with a calculator rather than implying greater precision than the dial supports.
PC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteThe result seems implausible
Check the distance unit, confirm that you used the chronograph seconds hand, verify the start and stop markers, and recalculate with rate = reading × distance. A unit mismatch—kilometers timed but miles reported—is a common cause of an apparently wrong result.
Frequently Asked Questions
Can I use a tachymeter at walking or running speed?
Yes, if the course is long enough for the event to finish within the scale’s 60-second window. For a slow pace, measure a longer distance and multiply the reading by that distance in kilometers or miles.
Do all chronograph watches have a tachymeter bezel?
No. A chronograph measures elapsed time, while a tachymeter is an additional scale or function. Some chronographs use a telemeter, pulsometer, or no calculation scale at all.
Why does my tachymeter scale start at 60 or 100 instead of zero?
The scale displays hourly rates, not elapsed seconds, so zero is not needed. Values near the 60-second end represent slower rates, while values toward the short-time end represent faster rates.
Can I read a tachymeter at night?
Only if the scale and the chronograph hand remain visible in the available light. Luminous hands do not necessarily make printed bezel numerals luminous, so low-light legibility depends on the specific watch design.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
