What one degree of camber looks like in millimeters

Quick answer: The sideways lean of a wheel, top compared with bottom, equals the height between those two points times the tangent of the camber angle. On a 17 inch wheel that works out to roughly 7.5 mm per degree, and it scales with wheel size at about 0.44 mm per degree for every inch of diameter. Half a degree is under 4 mm. Three degrees is over 2 cm. Knowing the millimeters gives you something you can check with a string and a ruler, which is the simplest way to confirm a phone or app reading before you trust it.

Alignment specs are written in degrees, and degrees are hard to picture. Is a car sitting at minus 1.5 degrees leaning a lot or a little? Is a 0.3 degree difference between the left and right side something you could ever see? Turning degrees into millimeters answers both, and it also shows how much measurement precision you actually need.

The formula

Take two points on the wheel’s outer face, one at the top and one at the bottom, and call the straight line distance between them the height, H. If the wheel is perfectly vertical, both points sit at the same sideways position. If it leans by a camber angle, the top moves sideways relative to the bottom by:

lean = H × tan(camber angle)

For the small angles involved in road cars, a quick version works fine: lean in millimeters is roughly H in millimeters times the angle in degrees times 0.01745.

Using the rim diameter as the height gives a good estimate. A 17 inch rim is 431.8 mm across, so one degree of camber leans the top of that rim by 431.8 × tan(1°), which is 7.5 mm.

Lean in millimeters, by rim size

These figures are lean in millimeters and use the nominal rim diameter as the height. They apply to negative and positive camber alike, since only the direction of the lean changes.

Rim (in)	0.5°	1°	1.5°	2°	3°
15	3.3	6.7	10.0	13.3	20.0
16	3.5	7.1	10.6	14.2	21.3
17	3.8	7.5	11.3	15.1	22.6
18	4.0	8.0	12.0	16.0	24.0
19	4.2	8.4	12.6	16.9	25.3
20	4.4	8.9	13.3	17.7	26.6

The actual distance between the top and bottom of the outer lip is a little more than the nominal diameter, because the lip flange adds height at each end. That makes the real numbers slightly larger than the table. Use the table to build intuition, and measure the height directly for the check below.

What this tells you

• A mild setting of about one degree negative, common on road cars, is under a centimeter of lean. On a 17 inch wheel, the top is tipped in by about 7.5 mm over the whole height of the rim. It is a small tilt, and it is easy to miss by eye.
• A tolerance of half a degree on either side of a target is about 4 mm of lean on that same wheel. That is the real size of the window you are trying to land in. If your spec sheet lists a range, this is how large it is on your wheels.
• A half degree difference between the left and right wheel is about 4 mm of difference in lean. That is roughly the size of the error a sloped floor can add, which the next section explains.
• An aggressive three degrees is more than two centimeters on a 17 inch wheel. At that point the tilt is easy to see.
• A tenth of a degree is under a millimeter, about 0.8 mm on a 17 inch wheel. Most phone apps display tenths of a degree, but your setup is rarely good to that level, for reasons below.

The floor adds its own lean

Camber is measured against gravity, so a car standing on a floor that slopes sideways leans with the floor. A floor slope of half a degree tilts every wheel by half a degree, which is the same 3.8 mm of lean on a 17 inch wheel. Over a typical track width of about 1.5 meters, that slope is a 13 mm height difference from one side of the car to the other. It pushes the two sides in opposite directions, so averaging left and right on the same axle cancels it, while the left to right difference does not.

A string and ruler check you can do in five minutes

A plumb line is a string with a small weight on it, and it points along true vertical, the same reference your phone uses. That makes it a simple independent check on the phone’s sensor.

1. Park on the same flat spot you used for the phone reading, steering straight, with the car settled.
2. Tie a small weight to a string, such as a washer or a nut. Hang the string a few centimeters outside the wheel, from a clamp or taped to the top of the fender, so it clears the tire. A tire sidewall usually bulges past the rim lip, so do not let the string touch the wheel.
3. Let the weight hang free and still, close to the floor. Shield it from wind and wait for it to stop swinging.
4. Measure the horizontal distance from the string to the outer lip of the rim at the top of the wheel, then at the bottom. Also measure the straight distance between those two points on the lip. Call that the height.
5. The difference between the two gaps is the lean. If the gap at the bottom is smaller than the gap at the top, the bottom of the wheel is farther from the car, so the camber is negative. If it is larger, the camber is positive.
6. Camber in degrees is roughly (difference ÷ height) × 57.3.

For example, a gap of 30 mm at the top and 22 mm at the bottom is a difference of 8 mm. Over a measured height of 450 mm that is (8 ÷ 450) × 57.3, which is about 1.0 degrees negative.

Reading each gap to the nearest millimeter over a height near 450 mm resolves roughly 0.13 degrees, so the string can tell you about the nearest tenth or so of a degree. If the phone and the string agree within about 0.2 degrees, the phone is doing its job. If they disagree by more, redo the phone reading first, using the flip method from our guide to measuring camber with a phone, before assuming anything else.

One limit worth knowing: the string and the phone share the same gravity reference, so a sloped floor fools both of them in the same way. The check confirms the phone’s sensor, and the floor is a separate problem to solve by averaging the left and right wheels.

Why bother with millimeters

Two reasons. The first is judgment: you can decide whether a gap between your reading and a spec is something you could ever feel or see, or just noise. A difference of 0.2 degrees on a 17 inch wheel is 1.5 mm of lean. The second is honesty about precision: an app that shows two decimal places is showing more digits than a driveway setup supports, so read the last digit as a hint and not as a measurement.

What the numbers cannot tell you

Camber is one of three main alignment angles, and a phone against the wheel face cannot measure the other two. Toe, which decides whether the wheels point inward or outward, matters a lot for tire wear. Caster, the tilt of the steering axis, needs the wheels turned and measured through an arc. Treat a camber reading as a check against the published specification for your vehicle, and use a shop with an alignment rack when you need all three angles or the adjustment itself.

Putting it to use

Camber Gauge, one of our apps, reads the camber angle from your phone’s motion sensors and saves all four wheels for each car. Use the table above to translate its readings into millimeters, and use the string check to confirm any reading you are about to act on.

Frequently asked questions

How many millimeters is one degree of camber?

On a 17 inch wheel, about 7.5 mm of lean from top to bottom of the rim. It scales with wheel size at roughly 0.44 mm per degree for every inch of diameter.

What is the camber to millimeters formula?

lean = H × tan(camber angle), where H is the straight line height between two points on the wheel’s outer face, top and bottom. Using the rim diameter as H gives a good estimate.

How big is half a degree of camber?

Under 4 mm on a 17 inch wheel, about 3.8 mm. Three degrees is over 2 cm, and a tenth of a degree is under a millimeter.

Can a sloped floor change my camber reading?

Yes. Camber is measured against gravity, so a floor with a half degree sideways slope adds about 3.8 mm of lean on a 17 inch wheel. Averaging left and right on one axle cancels it, but the left to right difference does not cancel.

How do I check a camber reading with a string and ruler?

Hang a plumb line a few centimeters outside the wheel. Measure the gap to the rim lip at the top and at the bottom, then camber in degrees is roughly (difference ÷ height) × 57.3. A larger gap at the top than the bottom means negative camber.

How precise can a phone camber reading be?

Phone apps often show tenths of a degree, but a driveway setup is rarely good to that level. Read the last digit as a hint, not a measurement.