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How to Measure for Trailer Hitch Drop

How to Measure for Trailer Hitch Drop

For safe and comfortable towing, your trailer should always be as level as possible. A level trailer handles well, promotes even tire wear, and minimizes strain on both the trailer and tow vehicle. However, with the many different tow vehicles and trailers out there, it's rare that any vehicle and trailer line up perfectly for towing. This is why ball mounts are made in a variety of sizes and come with what's known as rise and drop — to compensate for the height difference between your trailer and vehicle and allow for safe, level towing.
In this article:
Learn how to measure for ball mount rise and drop with our expert Jake in this video!

What are Rise and Drop?

Rise is the distance from the top of the shank to the top of the ball platform when the ball mount is oriented for greater coupler height.Drop is the distance from the top of the shank to the top of the ball platform when the ball mount is oriented for lower coupler height.
Measuring Drop Hitch Rise
Measuring rise on your drop hitch
Measuring drop hitch drop
Measuring drop on your drop hitch
Keeping a trailer level
Your tow vehicle and trailer should be level when towing

How Do I Measure for Rise and Drop?

To choose a ball mount with the correct rise and drop, you'll first need to take two measurements: your hitch height (Measurement A) and coupler height (Measurement B). The difference between them will be your rise or drop.
Step 1: Find your hitch height
Measure trailer hitch height
Measurement A: With the tow vehicle parked on level ground, measure from the ground to the top of your hitch receiver opening.
Step 2: Find your coupler height
Measure coupler height
Measurement B: With the trailer level, measure from the ground to the bottom of the coupler.
Step 3: Find the differenceFind the difference between the two measurements. Determine which has a greater height—your hitch or coupler—and find the difference between the two measurements. This is the amount of rise or drop you'll need. Hitch Height (A) - Coupler Height (B) = Rise/Drop (C) If your hitch height is greater, use a ball mount with a drop. If your coupler height is greater, use a ball mount with a rise. You can flip your drop hitch upside down to use it in either the rise or drop position as needed. Example: (15" Hitch Height) - (10" Coupler Height) = (5" Drop Needed) (12" Hitch Height) - (13" Coupler Height) = (1" Rise Needed) Examples: Measuring for rise and drop on a fixed vs adjustable ball mount:
Measuring for trailer hitch rise or drop (fixed hitch)
Measuring for rise or drop on a fixed ball mount
Measuring for trailer hitch rise or drop (adjustable hitch)
Measuring for rise or drop on an adjustable ball mount

What If I Tow Multiple Trailers?

If you need to tow multiple trailers, you should consider an adjustable ball mount. While fixed ball mounts have a set rise and drop, the rise and drop on adjustable ball mounts can be altered to accommodate different coupler heights. Adjustable models can save you the trouble and expense of using a separate ball mount for each trailer. Simply slide the ball mount platform up or down the shank and secure it in place with the locking pin to achieve the necessary rise or drop.
Adjustable Trailer Ball Mount

How Do I Choose an Adjustable Ball Mount?

To choose the best adjustable ball mount for your towing needs, first you'll need to determine the tongue weight of the heaviest trailer you want to tow. Make sure your adjustable ball mount has the weight capacity to support the loaded weight of the trailer. Also make sure the ball mount you choose has the correct size shank to fit your hitch's receiver (for instance, use a 2-inch ball mount with a 2-inch hitch receiver). Next, determine the tallest rise and deepest drop you'll need using the guidelines above—this will be the range you'll need in your ball mount. Finally, determine which hitch ball diameter you will need. Adjustable ball mounts usually come with at least one ball, and most come with two or three balls of different sizes for towing different trailers.
Adjustable Trailer Hitch Ball Mount
Still have questions?Give our experts a call at 800-298-8924, or contact us online. We're happy to assist any way we can!
Amber S.
About the AuthorAs a content writer for etrailer, I might spend my morning loading and unloading a bike on five different bike racks to figure out which is easiest to use. I might be in the parking lot, taking pictures of an impressive RV battery setup our techs came across in the shop and discussing the benefits of the setup with the owner. I might spend an afternoon in a manufacturer training classes for some hands-on experience with new products, and then sit down to assemble all this information into a coherent article.At etrailer, one of our core values is that we are always learning, and I learn something new every day. I start each morning with the goal in mind of taking all of this information and figuring out the best way to answer the questions people ask us (and the ones they don’t know to ask yet), and helping people get the solutions they need to make their lives easier, safer, and more fun. I’m a DIYer at heart, so it brings me great joy to help a fellow DIYer find what they’re looking for, whether that’s a product, an answer, or a community.
Related ContentRelated ProductsWritten by: Amber S.Updated on: 11/25/20

Terry Y.


Great article! I may be over thinking this, but if I take my measurements and adjust the ball hitch accordingly to have them level, won’t the weight of the trailer push the bumper height down when the trailer weight is applied? It seems that if they line up level when not attached, they are both going to dive down (the front of the trailer and rear of the truck) once connected. I am new to this and may not be looking at it correctly. Thanks in advance!

Etrailer Expert

Mike L.


@TerryY When choosing the height of your trailer ball, you'll want to allow 1-2 inches for the rear suspension squat caused by the trailer's tongue weight. You're definitely on the right track!



How does this math get affected by a vehicle that sags when not driven for a while due to air bags, or in this case nivomat self leveling shocks? Should you drive around for a mile or two loaded without the trailer, have it level out and then measure? Or do you measure while squatted and add a certain amount?

Etrailer Expert

Mike L.


@Nivomat Good question. You'll want to have the vehicle level itself before measuring. Or, if you know how much the suspension lifts, add that measurement into the mix. Borrow a ball mount from somebody if you don't already have one, and see how much squat that causes and how the air suspension compensates for that. Use the hitch height measurement you get once the suspension adjusts to the trailer's tongue weight. If you have any questions, let us know!



Excellent article, very detailed, simple to understand, and likely helped lots of people.

Etrailer Expert

Mike L.


That's awesome, we're glad you found the article helpful!



I bought a stealth hitch and tow package which says the top of the ball measures 18" but my light (~1500lbs loaded) trailer specs read the top of the 2" ball should sit about 15" from the ground, are there any drops that are compatible with the stealth hitch?

David B.


Is it 15 inches with the loaded trailer coupled? Or is it 15" up to the coupler while on level ground? There will always be some sag in suspension when you load up a trailer. What year/make/model is your BMW? If your trailer is completely level from the ground up to the coupler at 15 inches and your car is 18 inches that is a tolerable difference. We always want the trailer to be "level" but it will never be perfect. 3 inches up or down is going to be ok. I wouldn't go past 3 inches though.

Rick Z.


When you hook the trailer to the vehicle, the vehicle drops almost 2 inches. Doesn't this change the height of the hitch measurement?

David B.


Nope, you measure the hitch receiver while unloaded and the coupler on the trailer while it is level. The difference between the two measurements is the drop/rise that you will need. If the hitch drops 2 inches once coupled that means the the trailer tongue is dropping 2 inches and they will still be level. Let me know if you have any more questions Rick!



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