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:

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 rise on your drop hitch

Measuring drop on your drop hitch

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

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

Measurement B: With the trailer level, measure from the ground to the bottom of the coupler.

Step 3: Find the difference

Find 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.

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.

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As 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.

Questions and Comments about this Article

Karl 7/11/2021

If I’m within 1.75” of being level with a straight lock n roll hitch, do I need to buy the 2 1/2” drop receiver, or am I ok with the straight receiver that comes with my trailer? Taxa Trailer height is 21” and my 4Runner is 19.25”. Thanks.

Reply from Jon G. 7/12/2021

I would get the drop receiver so that you're within 1" of level instead of almost 2".

Nima 7/11/2021

My trailer (magic tilt) sits at 14 and the hitch (Mercedes 2018 gle350) sits 15.5". I can't decide what drop I should get. the Minimum is 2" but with extra tongue weight not sure if BM20 or BH20 would be the right fit.

Reply from Jon G. 7/12/2021

Either one would work just fine for you. The main difference between the 2 ball mounts is that one of them has a 1" diameter hole for the shank of the hitch ball while the other has a 1-1/4" diameter hole for the shank of the hitch ball.

Fabio S. 5/28/2021

Muy interesante el tema. Gracias me ha servido mucho para mi proyecto.

Roy 5/10/2021

I'll be towing a 2021 Nucamp tag xl boondock (teardrop) with a 2012 Kia Sportage which I believe the hitch receiver is at 13". Per manufacturer the trailer tounge height at level is 21 inches. Which type of ball mount do you recommend?

Reply from Jon G. 5/10/2021

From what you said that means you need a ball mount with an 8" rise. You could use part # C45112 or one of the adjustable options in the selection that I've linked for you.

Helpful Links

dept-pg-trailer_hitch_ball_mount-sf-adjustable_ball_mount-pc-rise_~_8_inch.aspx

Kevin S. 4/22/2021

i will be towing a 2014 spark with a tow bar behind my 2015 Itasca sonova class a motorhome do you have any reference and how much of a drop down reciever i will need???

Reply from Jon G. 4/22/2021

I honestly have no idea. I do have a different help article that you can check out though which I am attaching. This is geared more towards the measurements needed for a tow bar setup as opposed to the ball mount setup that you're looking at with this article.

Helpful Links

faq-high-low-adapter.aspx

Stephen P. 3/24/2021

Ken, Sorry, but I meant the adjustable part to be a given, but would I likely need a 6" or 10" drop?

Reply from Kef G. 3/25/2021

There are several heights of trailer tongues, so recommending a specific drop would be difficult. You should try to find a ball mount that has a sizeable range to account for those differences.

Stephen P. 3/20/2021

I just bought a 2021 Silverado 2500 with the Z71 package. This truck sits higher than most 1500's I've seen. The top of the receiver is 23 inches off the ground. I believe I need a drop hitch, but don't have anything to compare to yet. I expect to rent a trailer in a month or so and want to be prepared. I also plan to buy a camper 3-4 years down the road. Is there an 'average'? I'm guessing a 6' adjustable drop, but don't want to buy one, then something else later because this didn't work.

Reply from Kef G. 3/23/2021

You could get an adjustable ball mount. They give you a couple of positions so you can match them with a variety of trailer heights. I've linked to a list of them below. You'll just need to match what size hitch you have and what size ball you're expecting to use.

Helpful Links

dept-pg-trailer_hitch_ball_mount-sf-adjustable_ball_mount.aspx

Aaron C. 3/18/2021

How does this take into account for the weight of the trailer weighing down the tow vehicle. Would make since that you would need to measure with the trailer with a slight decline front to back as when the hitched the tow vehicle will dip a bit. Maybe not significant enough to make a difference. Thoughts?

Reply from Jon G. 3/18/2021

While it is true that there will be a slight decrease in the height of the nose of the trailer, it really shouldn't be that significant to make a difference. Also, if your trailer weighs at least half the curb weight of your tow vehicle you should really be using a weight distribution system anyways which would keep everything level.

Reply from Aaron C. 3/18/2021

@JonG Ok. I don’t think I’ll have an issue but it’s a good suggestion to check curb weight. Thanks for your help.

Reply from Jon G. 3/18/2021

@AaronC Happy to help!

Erica 3/16/2021

My trailer sits at 18.25 and my hitch sits at 18.75 does a half inch difference matter?

Reply from Jon G. 3/18/2021

If you're already within 1/2" of being level then I wouldn't worry about that. In all actuality your setup will probably be level once you hook up since the back of your vehicle will likely have a little bit of sag to it with the weight of the trailer tongue weight pushing down on it.

Reply from Erica 3/18/2021

@JonG that's what I thought but just wanted to check! Thanks for answering

Rick L. 1/12/2021

Do these measurements also apply for an RV and TOAD?

Reply from Jon G. 1/18/2021

Yes and no. A recreational towing setup is a little different because the tow bar is going to connect straight to the base plate kit as opposed to a hitch ball sitting inside the coupler. The same principle will apply for a recreational towing setup though. You will want to take these measurements and make sure that your tow bar is within 3" of being level. Here is an FAQ about the tow bar side of things that you can check out.

Helpful Links

faq-high-low-adapter.aspx

Dave G. 12/12/2020

If the drop is 7" should I choose a 6" or 8" drop?

Reply from Jon G. 12/14/2020

I'd go with a 6" because your tow vehicle will naturally have a little drop once the tongue weight is applied.