Technical

Video sensor sizes: from inches to millimetres

On a PTZ camera spec sheet, the sensor is given in inches: 1/2.8", 1/1.8", 2/3". For readers used to the metric system, these fractions say almost nothing. Which one is larger? By how much? This page converts each format into millimetres and area, then explains what sensor size changes in the picture.

Why inches mislead

Three pitfalls combine. First, a fraction with a decimal denominator is hard to read: 1/1.8" is 0.56 inch and 2/3" is 0.67 inch, so 2/3" is larger, which is not obvious at a glance. Second, and above all, a sensor "inch" is not a real inch: no 1" sensor measures 25.4 mm diagonally. Finally, the area actually used for 16:9 video can be smaller than the stated format: only the active size published by the manufacturer can be relied on.

The "optical inch": about 16 mm, not 25.4 mm

The notation comes from the camera tubes used until the late 1980s. The format referred to the outer diameter of the tube; the usable sensitive area covered only about two thirds of it. A 1-inch tube produced an image with a diagonal of about 16 mm. CMOS sensors kept this convention: a "1-inch" sensor measures about 16 mm diagonally, a 2/3" about 11 mm, a 1/2.8" about 6.4 mm. Rule of thumb: actual diagonal in mm ≈ value in inches × 16.

Cinema formats (Super 35, full frame, MFT) do not follow this convention: they are described directly in millimetres, often with reference to film formats.

The table in millimetres

Sorted from smallest to largest. Relative area: 1 = 1/3" sensor. Crop factor: ratio to the full-frame diagonal (43.3 mm). Examples: current models in 2026, checked on the manufacturer's website.

  • 1/3"

    Diagonal (mm)
    6.0
    Width × height (mm)
    4.8 × 3.6
    Area (mm²)
    17.3
    Area vs 1/3"
    ×1.0
    Crop vs full frame
    7.2
    Current examples
    Older-generation format, used as a reference point

  • 1/2.8"

    Diagonal (mm)
    6.4
    Width × height (mm)
    5.6 × 3.2
    Area (mm²)
    17.9
    Area vs 1/3"
    ×1.0
    Crop vs full frame
    6.7
    Current examples
    BirdDog X1, X1 Ultra, X5 Ultra, MAKI Ultra

  • 1/2"

    Diagonal (mm)
    8.0
    Width × height (mm)
    6.4 × 4.8
    Area (mm²)
    30.7
    Area vs 1/3"
    ×1.8
    Crop vs full frame
    5.4
    Current examples
    Older-generation format, used as a reference point

  • 1/1.5"active area 16:9

    Diagonal (mm)
    8.9
    Width × height (mm)
    7.74 × 4.35
    Area (mm²)
    33.7
    Area vs 1/3"
    ×1.9
    Crop vs full frame
    4.9
    Current examples
    Z CAM P2-R1N 24x

  • 1/1.8" *

    Diagonal (mm)
    8.9
    Width × height (mm)
    7.18 × 5.32
    Area (mm²)
    38.2
    Area vs 1/3"
    ×2.2
    Crop vs full frame
    4.8
    Current examples
    BirdDog X4 Ultra, O4 ; secondary wide camera of the BirdDog XL Ultra

  • 1/1.3"active area 16:9

    Diagonal (mm)
    10.5
    Width × height (mm)
    9.19 × 5.17
    Area (mm²)
    47.5
    Area vs 1/3"
    ×2.7
    Crop vs full frame
    4.1
    Current examples
    Z CAM P2-R1N 18x

  • 2/3"

    Diagonal (mm)
    11.0
    Width × height (mm)
    8.8 × 6.6
    Area (mm²)
    58.1
    Area vs 1/3"
    ×3.4
    Crop vs full frame
    3.9
    Current examples
    Studio and shoulder-mount broadcast cameras (e.g. Sony HDC-5500Vnot in the catalogue)

  • Super 16

    Diagonal (mm)
    14.5
    Width × height (mm)
    12.52 × 7.41
    Area (mm²)
    92.8
    Area vs 1/3"
    ×5.4
    Crop vs full frame
    3.0
    Current examples
    16 mm film reference

  • 1"

    Diagonal (mm)
    15.9
    Width × height (mm)
    13.2 × 8.8
    Area (mm²)
    116.2
    Area vs 1/3"
    ×6.7
    Crop vs full frame
    2.7
    Current examples
    Z CAM E2-M4G Mark II

  • Micro Four Thirds (MFT)

    Diagonal (mm)
    21.6
    Width × height (mm)
    17.3 × 13.0
    Area (mm²)
    224.9
    Area vs 1/3"
    ×13
    Crop vs full frame
    2.0
    Current examples
    Z CAM E2-M4 Mark II ; BirdDog XL Ultra (main sensor)

  • Super 35

    Diagonal (mm)
    28.6
    Width × height (mm)
    24.89 × 14.0
    Area (mm²)
    348.5
    Area vs 1/3"
    ×20
    Crop vs full frame
    1.5
    Current examples
    Z CAM E2-S6 Mark II, E2-S6G Mark II

  • Full frame (36 × 24)

    Diagonal (mm)
    43.3
    Width × height (mm)
    36 × 24
    Area (mm²)
    864
    Area vs 1/3"
    ×50
    Crop vs full frame
    1.0
    Current examples
    Z CAM E2-F6 Mark II, E2-F8 Mark II

  • 65 mm

    Diagonal (mm)
    55.9
    Width × height (mm)
    50.81 × 23.32
    Area (mm²)
    1,185
    Area vs 1/3"
    ×69
    Crop vs full frame
    0.77
    Current examples
    Large-format cinema (e.g. Blackmagic URSA Cine 17K 65not in the catalogue)

The two Z CAM rows give the 16:9 active area published by Z CAM. The other rows give typical dimensions for the format: an individual model may differ depending on its sensor and aspect ratio, and the manufacturer's spec sheet prevails.

* BirdDog states 1/1.8" without publishing dimensions in mm: typical values for the format (4:3), to be confirmed.

Last checked:

Sizes to scale

PTZ formats, from 1/3" to 1"

1/3" to 1" sensors to scale Rectangles to scale, aligned on the bottom-left corner, from the 1/3" sensor (6 mm diagonal) to the 1" sensor (about 16 mm). 1" 15.9 mm 2/3" 11.0 mm 1/1.8" 8.9 mm 1/1.3" 10.5 mm 1/2" 8.0 mm 1/1.5" 8.9 mm 1/3" 6.0 mm 1/2.8" 6.4 mm 5 mm

Full view, up to full frame

1/3" to full-frame sensors to scale Rectangles to scale, aligned on the bottom-left corner, from the small PTZ formats to 36 × 24 full frame (43.3 mm diagonal). Full frame 43.3 mm Super 35 28.6 mm Micro 4/3 21.6 mm 1" 15.9 mm Super 16 14.5 mm 2/3" 11.0 mm 1/3" to 1/1.3" 6.0 to 10.5 mm 10 mm
Also show 65 mm
1/3" to 65 mm sensors to scale Rectangles to scale, aligned on the bottom-left corner, from the small PTZ formats to the 65 mm large cinema format. Full frame 43.3 mm 65 mm 55.9 mm Super 35 28.6 mm Micro 4/3 21.6 mm 1" 15.9 mm Super 16 14.5 mm 2/3" 11.0 mm 1/3" to 1/1.3" 6.0 to 10.5 mm 10 mm

A 1/1.3" sensor in 16:9 offers about 2.7 times the area of a 1/2.8"; a full-frame sensor, about 48 times.

Rectangles to scale, aligned bottom left. Dashed outline: 16:9 active area published by the manufacturer.

What sensor size changes in practice

Low light

With comparable technology and resolution, a larger sensor collects more light per photosite, so there is less noise in a dimly lit room. Sensor generation and processing also matter: size is not the only criterion.

Depth of field

With equivalent framing and aperture, a large sensor gives a more blurred background. Useful for an interview shot; less desirable when focus must cover an entire stage or a conference room.

Zoom and size (PTZ)

The larger the sensor, the larger the lens that covers it. This is why PTZ cameras with very long zooms often keep a small sensor, while PTZ cameras with large sensors offer shorter zooms. An example from the catalogue: the Z CAM P2-R1N comes in 1/1.5" with a 24x zoom and in 1/1.3" with an 18x zoom.

Crop factor

It is used to compare fields of view. A focal length multiplied by the crop factor gives the focal length that would produce the same framing on full frame.

Resolution

Size says nothing about pixel count. A 4K 1/2.8" sensor has much smaller photosites than a 4K Super 35 sensor.

Frequently asked questions

1/1.8" or 2/3": which is larger?
The 2/3" (11 mm diagonal versus 8.9 mm), which means about 50% more area.
Why doesn't a 1" sensor measure 25.4 mm?
It is a legacy of camera tubes: the format referred to the tube diameter, not the sensitive area. A 1" sensor measures about 16 mm diagonally.
Why do two sensors of different formats sometimes have the same diagonal?
Because the nominal format describes the whole sensor, whereas 16:9 video reads only part of it. The active area published by the manufacturer is the only comparable measurement.
Does a larger sensor always give a better picture?
No. It helps in low light and for background blur, but it requires a larger lens and often a shorter zoom. The right format depends on the scene.
Which format for a conference room PTZ camera?
A 1/2.8" sensor covers most well-lit rooms with a long zoom; a larger sensor makes sense in low light or for a more "cinematic" look. Resellers can help choose the right format for the venue.
What is the crop factor?
The ratio between the full-frame diagonal (43.3 mm) and the diagonal of the sensor.

Further reading

BirdDog

PTZ and box cameras, converters, control and AV integration.

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Z CAM

E2 Mark II cinema cameras and P2-R1N PTZ cameras.

View page

Remote PTZ control

Use case: operating PTZ cameras remotely with BirdDog Connect.

View page

Control protocols

VISCA, NDI® PTZ, ONVIF and the other protocols that drive cameras.

View page

Where to buy

Resellers can help choose the right format for the venue.

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Contact

A question about a format or a camera in the catalogue: HoriCast points you to the right contact in France.

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An AV project in France? Contact HoriCast.

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