Convex Mirror Placement: Distance, Height & Angle

Convex Mirror Placement: Getting Distance, Height, and Angle Right

Mirror placement is geometry. A correctly sized mirror in the wrong position covers nothing useful; a slightly oversized mirror in the right position covers everything that matters. The three numbers that determine whether a mirror solves the problem are viewing distance, mounting height, and tilt angle. This guide sets the practical ranges for the most common parking-lot, garage, drive-thru, and warehouse applications.

What Are the Key Placement Specs for a Convex Mirror?

A convex parking-lot mirror is placed at a viewing distance of 4 to 7 times its diameter from the typical driver eye-line, mounted at 8 to 10 feet to mirror center for outdoor parking lots and garages, and tilted 5 to 15 degrees down from horizontal toward the driver eye-line at 4 feet 6 inches. Indoor warehouse aisles use 9 to 12 feet to mirror center; drive-thru queues use 7 to 9 feet. Cojo placed a 30-inch outdoor convex mirror on a Hillsboro grocery anchor pad blind corner in February 2026 at 9 feet to mirror center with a 7-degree downward tilt, covering a viewing distance of 14 feet to the cross-traffic point.

Viewing Distance: How Far Should the Mirror Be from the Driver?

Effective coverage radius from a convex mirror is roughly 4 to 7 times its diameter at typical mounting height. The rule rolls out to:

Mirror diameter	Effective viewing distance
18 in	6 ft to 11 ft
24 in	8 ft to 14 ft
30 in	10 ft to 18 ft
36 in	12 ft to 21 ft
48 in	16 ft to 28 ft

Beyond the maximum viewing distance for the diameter, the cross-traffic image becomes too small to read. Inside the minimum, the image is large but the angle of incidence is poor and the driver sees mostly the ground. The 4-to-7-times-diameter rule is a practical sweet spot from facility-management practice; specific applications can fall outside the range when other constraints dominate.

Mounting Height: How High Above the Ground?

Mounting height varies by application:

• Outdoor parking lot or garage: 8 to 10 feet to mirror center. Lower than 8 feet fills the field with adjacent parked cars; higher than 10 feet shows the building roofline.
• Indoor warehouse aisle: 9 to 12 feet to mirror center. The forklift mast typically reaches 7 to 9 feet at travel position; the mirror mounts above mast travel clearance.
• Drive-thru queue: 7 to 9 feet to mirror center. Aligns with driver-window height of about 4 feet 6 inches at typical viewing distance.
• Loading dock corner: 9 to 11 feet to mirror center. Truck-driver eye-line in a dock-backing situation is approximately 6 to 8 feet above grade.
• Pedestrian crossing or doorway: 7 to 8 feet to mirror center. Aligns with pedestrian eye-line of about 5 feet at conversational viewing distance.

Tilt Angle: How Should the Mirror Be Aimed?

Tilt is the most-often misadjusted parameter. The right tilt aims the reflected scene at the driver's eyes, not at the ground or the sky.

Mounting height	Driver eye-line	Recommended tilt
8 ft	4 ft 6 in (car)	5 to 8 degrees down
9 ft	4 ft 6 in (car)	7 to 11 degrees down
10 ft	4 ft 6 in (car)	9 to 14 degrees down
9 ft	5 ft 6 in (forklift seat)	5 to 8 degrees down
11 ft	5 ft 6 in (forklift seat)	9 to 13 degrees down

The verification check after install is simple: stand at the typical driver position and look at the mirror. The reflected scene should show the cross-traffic at approximately the same height as approaching vehicles. If you see mostly ground, tilt up. If you see mostly building roofline or sky, tilt down.

Offset: Where Around the Corner Should the Mirror Be?

For a 90-degree blind corner, the optimal mirror position is on the far side of the corner from the approaching traffic, at about 3 to 5 feet of inside-corner offset. The offset gives the mirror a clear view of both directions of cross-traffic without one direction blocking the other.

For T-intersections and cross-aisles, the mirror sits on the wall directly opposite the approach direction, centered on the cross-aisle to give symmetric coverage of both perpendicular approaches.

For four-way intersections (warehouse), the mirror is suspended from the ceiling at the geometric center of the intersection, level with the ceiling structure.

Sight-Line Verification

After mounting, before final torque, verify the placement by walking the typical approach pattern at the driver eye-line height:

1. Stand at the start of the approach (typically 30 to 60 feet from the corner)
2. Look at the mirror as you approach
3. Confirm the cross-traffic is visible from the start of the approach to the corner itself
4. If the cross-traffic disappears at any point in the approach, the mirror is too low, too small, or off-angle
5. Adjust before fully tightening hardware

A mirror that fails sight-line verification on day one will fail it every day. The 5 minutes of verification before final torque eliminates the cost of a re-install later.

What About Multiple Mirrors at the Same Intersection?

Some intersections need more than one mirror:

• Outdoor four-way intersections. Two mirrors on opposing pole-mounts cover all four directions because no ceiling exists for a full-dome suspension.
• Long-curve blind spots. A series of mirrors every 30 to 60 feet along a curving aisle covers segments where a single mirror would miss the geometry.
• Multi-level transitions. Garage ramps with both up- and down-traffic at a tight curve need a mirror for each level.

When using multiple mirrors, place each one at its own optimal viewing-distance, height, and angle for the specific approach it serves. Treating them as a single installation reduces effectiveness.

Code and Standards References

• OSHA 1910.176(a) -- Storage aisle clearance and forklift sight-line aid framing.
• OSHA 1910.178(n)(7) -- Powered industrial truck operator visibility.
• FHWA MUTCD Section 9C.06 -- Sight distance for traffic-control devices on roadways. Public-roadway reference; private-lot best practice draws from the same geometry.
• ADA Standards 502 -- Accessible parking sight-line considerations.

None of these mandate specific placement; they govern the underlying sight-line conditions that mirror placement is meant to address.

Real-World Cojo Placement: Hillsboro Grocery Anchor Pad

On a Hillsboro grocery anchor pad in February 2026, Cojo placed a 30-inch outdoor polycarbonate convex mirror at the southeast lot blind corner. Placement specs:

• Mirror diameter: 30 in
• Mounting height: 9 ft to mirror center
• Tilt: 7 degrees down from horizontal
• Offset: 4 ft on the far side of the corner from approaching traffic
• Viewing distance to cross-traffic: 14 ft
• Driver eye-line: 4 ft 6 in (car)

Sight-line verification at install confirmed the cross-traffic was visible from 32 feet at the start of the approach to within 6 feet of the corner. The corner has had zero reported near-miss incidents in the year since installation.

Get the Placement Right Before Final Torque

Mirror placement is geometry, and geometry is unforgiving. Five minutes of sight-line verification before final torque saves the cost of a re-install. Cojo specifies and places convex mirrors as part of property-management retrofit packages across the I-5 corridor. Contact Cojo for a placement assessment.

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