If you’ve ever shopped for a mount for a ham radio, a Garmin GPS, a police scanner, or a Sirius radio, you’ve probably run into the term “AMPS pattern” without much explanation of what it actually means. It’s one of those pieces of mounting jargon that gets assumed rather than explained — but understanding it makes finding compatible hardware a lot easier.
The short version: the AMPS pattern is a standard four-hole bolt pattern that appears on the back of hundreds of different electronic devices and on thousands of mounts. If your device has AMPS holes and your mount has AMPS holes, they connect. It’s the closest thing the consumer mount industry has to a universal standard, and knowing how to spot it saves a lot of guesswork.
What the AMPS Pattern Actually Is
The AMPS pattern consists of four threaded holes arranged in a rectangle, spaced 1.188 inches wide by 1.813 inches tall (center to center). That’s it. Those specific dimensions are what define the pattern. As long as the hole spacing matches, any AMPS-compatible device will bolt to any AMPS-compatible mount — regardless of brand.
Some manufacturers only use two of the four holes, typically the diagonal pair. That diagonal measurement is 1.912 inches center to center. Many mounts accommodate both the full four-hole pattern and the two-hole diagonal, so compatibility is rarely an issue even when a device only has two holes.
The pattern is sometimes called the “4-hole AMPS pattern” to distinguish it from the two-hole variant. If a product listing says it supports AMPS, it supports both unless otherwise specified.
4-hole rectangle: 1.188″ × 1.813″ (center to center)
2-hole diagonal: 1.912″ (center to center)
Screw size: typically M4 or 8-32, varies by manufacturer — always check before ordering hardware
Where the Name Comes From
AMPS stands for Advanced Mobile Phone System — the original analog cellular network that launched in North America in the early 1980s. The pattern was developed as a mounting standard for early mobile phones and car phone equipment. The cellular industry has moved on entirely, but the hole pattern stuck around and got adopted by the broader consumer electronics mount industry. Today the name is essentially a legacy term; most people who use AMPS mounts have never thought about where the name came from.
Devices That Use the AMPS Pattern
The AMPS pattern shows up across a surprisingly wide range of devices. Here’s where you’re most likely to encounter it:
Ham Radio Control Heads
This is where the AMPS pattern is most deeply embedded. Yaesu, Icom, and Kenwood all use AMPS-spaced holes on their head mounting plates. Icom’s MB-63 control head mounting plate and Yaesu’s YK-8900 bracket both follow the pattern. Because ham radio operators frequently build custom mobile installations, AMPS compatibility matters — it means a head bracket can bolt to a seat bolt mount, a flat surface mount, a cup holder mount, or any other AMPS-compatible base without needing a proprietary adapter. You can read more about the full range of mounting options in our ham radio car mount guide and our article specifically on RAM Mounts for ham radios.
Garmin and TomTom GPS Cradles
Garmin motorcycle GPS cradles — including those for the Zumo series — use the AMPS pattern on the back of the powered cradle. This is what allows a Garmin Zumo cradle to bolt directly to a RAM Mounts handlebar base or mirror mount without any special adapter. The AMPS holes on the cradle line up with the AMPS holes on the RAM plate, and the screws that came with the GPS hardware hold it together. TomTom Rider cradles use the same pattern. Car GPS cradles from Garmin generally use a 17mm ball socket rather than AMPS, but motorcycle cradles are almost universally AMPS.
Visit our Motorcycle GPS Mounts Hub for more information.
Sirius and XM Satellite Radio Docks
After the Sirius/XM merger, the combined company standardized on the AMPS pattern for satellite radio docks. Almost every powered Sirius cradle made in the past fifteen years has four AMPS holes on the back. This is useful because it means a Sirius dock can use the same seat bolt mount, suction cup mount, or cup holder mount as a ham radio head — the hardware is completely interchangeable as long as the weight rating is appropriate.
Police and Handheld Scanners
Many Uniden and other scanner cradles use the AMPS pattern, which is part of why scanner mounting options are so plentiful despite scanners being a niche product. A standard AMPS seat bolt mount handles a scanner head just as well as it handles a ham radio head.
Some Smartphone Cradles
A number of aftermarket phone cradles — particularly older Arkon and Bracketron models — are built around the AMPS pattern. The cradle itself holds the phone, and the back of the cradle has AMPS holes to attach to any compatible mount base. This approach is less common now that most phone mounts use integrated ball-and-socket designs, but you still see it on heavier-duty cradles designed for extended use.
Mount Types That Support AMPS
Because the pattern is so widely used, there are AMPS-compatible versions of almost every mount base type. The most common:
Seat Bolt Mount
The most popular base for ham radio and scanner installations. The mount clamps to the seat bolt on the vehicle floor, and an 18-inch flexible gooseneck arm positions the device at console level. The top of the arm has an AMPS plate. Installation takes about five minutes with a wrench. The Arkon Seat Bolt Mount is a fine example of this type of mounting accessory.
Flat Surface Mount
Bolts or adheres to a flat section of dashboard or console. A short rigid arm with ball-and-socket adjustment holds the AMPS plate at the tip. Good for permanent installations where you want a low-profile setup. RAM’s flat surface mount with AMPS adapter is one of the most widely used options in this category.
Cup Holder Mount
An expandable base fits into a standard cup holder, with a gooseneck or rigid arm and an AMPS plate at the top. No tools required. Works well in fixed cup holders; less stable in pull-out or sliding designs. The easiest installation option for any AMPS-compatible device.
Suction Cup Mount
Attaches to the windshield or dashboard. Useful for temporary installs or for moving a device between vehicles. Most suction cup mounts with AMPS adapters include a ball-and-socket adjustment for angle. Make sure to check your state laws — some states restrict objects mounted on the windshield.
Handlebar and Mirror Mounts (Motorcycle)
A lot of companies manufacture handlebar bases and mirror stem bases that terminate in an AMPS plate, which is what allows a Garmin Zumo cradle or TomTom Rider cradle to bolt directly to a motorcycle without any brand-specific adapter. This is one of the most practical applications of the AMPS standard — it lets a GPS manufacturer focus on making a good cradle without having to design their own mounting system from scratch. Garmin offers an AMPS pattern mount. It’s included with their Zumo line of GPS devices.
4-Hole vs. 2-Hole: What to Watch For
Most AMPS mounts support both the full four-hole pattern and the two-hole diagonal. But a few things are worth knowing:
When a device only uses two holes, it’s typically the diagonal pair — top-left and bottom-right, or top-right and bottom-left. The mount’s AMPS plate will have all four holes, and you simply use the two that align with your device’s holes. The other two stay empty.
Screws are not always included or universal. Garmin cradles come with their own screws sized for their specific mounting plates. Ham radio head brackets often come with screws too, but the thread size can vary (M4 metric and 8-32 imperial are both common). If you’re building a custom installation with mismatched components, have a small assortment of M4 and 8-32 screws on hand before you start.
Standoff height occasionally matters. If a device’s AMPS holes are recessed or the back of the housing protrudes, a standard flat AMPS plate may not sit flush. In those cases, a mount with short standoff posts — or adding small nylon spacers — solves the problem.
AMPS vs. VESA: Knowing the Difference
AMPS is for small electronics — phones, GPS units, radio heads, scanners. Once you get into larger displays, monitors, and televisions, the AMPS hole spacing is too small and a different standard takes over: VESA. VESA patterns are specified in millimeters — the most common are 75×75mm and 100×100mm, meaning the holes are 75mm or 100mm apart. If you’re mounting a tablet or larger display and the mount mentions VESA, that’s a different world from AMPS entirely.
Why It Matters in Practice
The practical value of the AMPS standard is that it breaks the link between device brand and mount brand. You don’t need a Garmin mount for a Garmin GPS or an Icom mount for an Icom radio — you need an AMPS mount, and those are made by dozens of manufacturers at every price point. It also means hardware is reusable across devices: the seat bolt mount you bought for your scanner will work just as well for your ham radio head when you upgrade. The arm, the base, and the plate all stay; only the device changes.
For anyone building a mobile installation — whether it’s a ham radio shack in a truck, a GPS setup on a motorcycle, or a scanner mount in a patrol car — the AMPS pattern is the foundation everything else is built around.
