Free tool
Hitch drop calculator
Two tape-measure numbers and you know exactly what size drop hitch you need — the drop in inches, the ball mount size to actually buy, and whether your trailer ends up level, nose-high or nose-down.
Drop ball mount
Rides level — this is the setup you want.
| Measurement | Height |
|---|---|
| Receiver, as measured | 21" |
| Rear squat allowed | −1" |
| Receiver while towing | 20" |
| Coupler, trailer level | 17" |
| Difference to close | 3" drop |
What this means before you buy
- You need a ball mount that moves the ball 3" down. The closest stock size is a 3" drop mount.
- Most 3" ball mounts are reversible — flip the same part over and it becomes a 3" rise, which is worth knowing if you tow a second trailer.
- This allows 1" of rear squat, so the numbers describe the trailer while you are towing, not while it sits in the driveway. Expect it to look slightly nose-up before you hitch up.
- Ball mounts are rated as an assembly. The drop shank, the ball and the receiver each carry their own gross trailer weight and tongue weight ratings, and the lowest one is your real limit — a deeper drop usually lowers it.
Geometry only. Always confirm the gross trailer weight and tongue weight ratings stamped on your receiver, shank and coupler, and re-check the trailer sits level once it is loaded — cargo position changes the attitude as much as the ball mount does.
How to measure for a drop hitch
Four steps and a tape measure. The whole job takes about five minutes and it is the difference between a trailer that tracks straight and one that hunts across the lane at 65 mph.
- 1
Park on level ground
Put the truck and the trailer on the same flat surface. A sloped driveway throws both measurements off in opposite directions and is the single most common reason a drop hitch comes out wrong.
- 2
Measure the receiver height
Measure from the ground to the top inside edge of the receiver tube opening. Do it with the truck loaded the way you tow — fuel, passengers, gear in the bed — because that load changes the height.
- 3
Level the trailer, then measure the coupler
Use the tongue jack to bring the trailer level (a spirit level on the frame rail, not the floor). Then measure from the ground to the bottom of the coupler.
- 4
Subtract to get the drop
Receiver height minus coupler height is your drop. A positive number means you need a drop mount of that many inches; a negative number means you need a rise. Round to the nearest size sold and check the trailer still sits level or a touch nose-down.
What size ball does your coupler take?
The ball size is stamped on the coupler and it is not negotiable — an undersized ball can appear to latch and then release under load. Check it before you order the mount.
| Coupler stamp | Ball diameter | Typical rating | What it is used for |
|---|---|---|---|
| 1-7/8" | 1-7/8" | up to ~3,500 lb | Small utility, jet-ski and pop-up trailers. |
| 2" | 2" | up to ~8,000 lb | The default: most utility, boat, car and small travel trailers. |
| 2-5/16" | 2-5/16" | up to ~30,000 lb | Heavy travel trailers, equipment and car haulers. |
Receiver classes and shank sizes
The shank has to match the receiver tube, and the whole chain is only as strong as its weakest link. These are the classes you will meet on a pickup.
| Class | Receiver tube | Max trailer weight | Max tongue weight | Where you see it |
|---|---|---|---|---|
| Class II | 1-1/4" | up to 3,500 lb | 350 lb | Cars and crossovers; rare on a pickup. |
| Class III | 2" | up to 8,000 lb | 800 lb | The standard factory receiver on half-ton pickups. |
| Class IV | 2" | up to 10,000 lb | 1,000 lb | Heavy-duty 2" receivers; same shank, higher rating. |
| Class V | 2-1/2" or 3" | up to 20,000 lb | 2,700 lb | Three-quarter and one-ton trucks; needs a matching shank. |
These are the industry class definitions, not your truck's rating. Your vehicle's own towing and tongue weight limits come from the owner's manual and the door-jamb sticker, and they are frequently lower than the hitch hardware allows.
Now check the weights
Getting the trailer level is the geometry half of towing safely. These handle the other half.
Hitch drop — frequently asked
What size drop hitch do I need?
Measure from the ground to the top of your receiver opening, then from the ground to the bottom of the coupler with the trailer level. Subtract the coupler height from the receiver height — that difference in inches is the drop you need. A truck with a 22-inch receiver pulling a trailer with a 17-inch coupler needs a 5-inch drop. Ball mounts are sold in whole inches, so round to the nearest one and prefer the deeper drop if you land between sizes.
How do I measure hitch drop?
Two measurements from level ground: the top inside of the receiver tube on the truck, and the bottom of the coupler on the trailer with the trailer levelled by its tongue jack. Receiver height minus coupler height equals the drop. Measure the truck loaded as you would tow it, since a full tank, passengers and gear in the bed all lower the receiver.
Should a trailer be level when towing?
Level, or very slightly nose-down — about half an inch to an inch low at the front. Level keeps the weight split between the trailer axles the way the manufacturer intended, keeps tongue weight in the 10 to 15 per cent range, and keeps the trailer tracking straight. A slight nose-down attitude is the safe side of level; nose-high is not.
What happens if the trailer is nose-high?
A nose-high trailer shifts load rearward, off the tongue and onto the trailer's back axle. That reduces tongue weight, unloads the tow vehicle's rear axle and is the classic cause of trailer sway at highway speed. It also overloads the rear trailer tires and makes braking worse. If your setup comes out nose-high, go to a deeper drop before you tow.
What happens if the trailer is nose-low?
A nose-down trailer puts extra weight on the front trailer axle and on the tongue. It is much safer than nose-high, but a big nose-down angle scrubs the front trailer tires, can bottom the front of the trailer on driveways and ramps, and pushes tongue weight past the 15 per cent guideline — which eats into your truck's payload. An inch or so low is fine; three inches is not.
Can I flip a drop hitch over to use it as a rise?
Most standard ball mounts are reversible — the same part gives you a drop one way up and a rise the other. Two caveats: the weight rating can differ between the two orientations, so check the stamp on the shank, and adjustable or multi-ball mounts are often not reversible at all. Never flip a mount that the manufacturer marks as one-way.
How much does a truck squat when you hitch up a trailer?
A half-ton pickup typically drops 1 to 2 inches at the rear under normal tongue weight; a heavy trailer on a light truck can be more. That squat lowers the receiver after you hitch up, so a trailer that looked level in the driveway ends up slightly nose-up on the road. Either measure the receiver with the truck already loaded, or allow for the squat in the calculator above.
What size ball do I need for my trailer?
The ball must match the coupler exactly — the size is stamped on the coupler itself. The three common sizes are 1-7/8 inch for small utility and pop-up trailers, 2 inch for most utility, boat and small travel trailers, and 2-5/16 inch for heavy travel trailers and equipment haulers. A 2-inch ball in a 2-5/16 coupler will feel like it latches and then come off the ball.
Does a deeper drop hitch lower the towing capacity?
Usually yes. The further the ball sits from the receiver, the more leverage the tongue weight applies to the shank, so manufacturers derate deeper drops — a 10-inch drop mount is commonly rated well below the same maker's 2-inch mount. The whole chain matters: receiver, shank, ball and coupler each have a gross trailer weight and tongue weight rating, and your real limit is the lowest number in the chain.
What is the difference between drop and rise on a ball mount?
Both describe how far the ball platform sits from the shank centreline. A drop puts the ball below the receiver, which is what a pickup normally needs because trucks sit high. A rise puts the ball above the receiver, needed when towing a tall trailer with a low vehicle or a lifted trailer. The measurement is taken from the top of the shank to the top of the ball platform.
