If you've ever wondered what size a single pixel on a digital camera is, or how different sensor sizes effect image quality, then this article is for you. For a more basic introduction into what a sensor is, have a look at our Sensor Technology Guide.

What difference does pixel and sensor size make?

A larger sensor is better, as this allows larger pixels on the sensor, which in turn helps record more light. A larger sensor will also allow the manufacturer to offer a wider ISO range, and the camera will be able to shoot at higher ISO speeds, whilst keeping noise low. For example, a Full-Frame sensor is bigger than an APS-C sensor, and an APS-C sensor is larger than a Micro Four Thirds sensor, and therefore the larger the sensor, the larger the light collecting area, and the larger the pixels will be, assuming all sensors are the same megapixel count, and use the same sensor technology.

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How big is a pixel?

The more pixels you put on a sensor, then the smaller the pixel will be. For example an 18 megapixel sensor will have smaller pixels than a 12 megapixel sensor, assuming both sensors were exactly the same size. The size of each Pixel is measured and shown as a Micron with the symbol μm or simply μ, and is short for micrometre (Wikipedia). Pixel size ranges from 1.1 microns in the smallest smartphone sensor, to 8.4 microns in a Full-Frame sensor. As an example, the 8 megapixel sensor above has a resolution of 3,264 x 2,448 pixels, with 327,184 pixels in an area just 1mm x 1mm in size. 

We've previously looked at sensor size, but are going to look at sensor size in more detail, going down to the pixel level.

Does sensor technology and type matter?

Another consideration is whether the sensor is a BSI (Back Side Illuminated) CMOS sensor, a standard CMOS sensor or a CCD sensor. A BSI sensor has the wiring moved out of the way, which means the individual light gathering areas of the pixel can be larger, allowing more light to reach them, giving better low-light performance, as well as improved dynamic range. You also need to be aware of the advances made in sensor technology over the years, with manufacturers continually working to reduce image noise, and improve sensor performance.

We look at the different technology, such as CCD, CMOS, and BSI sensors in our guide to digital image sensor technology, and if you're looking for additional information on sensor types this would be well worth reading. 

Nb. If you're looking for the best sensor for low-light, then you should also be aware that the lens aperture affects low light performance, a larger aperture is better (ie. f/1.7 is better than f/3.3), and optical image stabilisation (OIS) can also help get sharp shots in low light, for example, when using slower shutter speeds. Sensor technology and size is one aspect of image quality, with the lens, and image processing of the camera also playing an important part in producing the final image.

Here we compare different camera sensor sizes found in the different types of camera, including smartphones, compact cameras, mirrorless cameras, Digital SLRs and medium format. We will be showing sample images, and as the sensor (and pixel) size increases, you can see for yourself how noise is affected.

You can jump straight to each sensor size here:

• Smartphone
• Compact Camera
• Premium Compact (1inch +) 
• Micro Four Thirds
• APS-C
• Full-Frame
• Medium Format

Smart Phone Sensors – 1/4 to 1/2.3inch

The sensor in a smartphone can vary in size from phone to phone, and smartphones often feature the smallest sensors available. The compact size of smartphones means that they very rarely feature any optical zoom, instead they often opt for a prime lens, with a bright aperture, or alternatively more than one camera to enable additional features, such as wide-angle lenses, or dual cameras etc.

Here's a table showing a number of common smartphone resolutions, the sensor type, size, and pixel size in microns, along with a link to more detail on each smartphone:

Most smartphones feature a small sensor and a limited ISO range, with many smartphones having a maximum ISO speed of ISO800, and ISO1600, although sometimes they will offer higher ISO speeds. This can mean smartphones struggle in low-light unless they feature a bright aperture, optical image stabilisation, or other features to help in low-light situations.

The exception is the Panasonic Lumix CM1, which features a 1inch sensor. There's also the Nokia PureView 808 which features a 1/1.2inch sensor.

Huawei P8 at ISO1600 (at 100%):

For more on smartphones, have a look at the Top 10 Best Smartphones for Photography, or look at more smartphone reviews.

Compact Camera Sensors - 1/3inch to 1/2inch

The sensor above from a Vivitar Vivicam 8370, is an 8mp 1/2.5inch CMOS sensor with a width of 5.7mm, a resolution of 3264x2448, and 1.74 micron pixel size, meaning a line of 572 pixels takes up 1mm. Compact camera sensors vary in size from 1/3inch to 1/1.7inch or larger. We look at larger compact camera sensors in the next section on premium compact cameras.

Here's a table showing a number of common compact camera resolutions, the sensor type, size, and pixel size in microns, along with a link to more detail on each camera:

The latest BSI CMOS sensor compact cameras offers a wide ISO range from ISO100 often up to ISO6400. With a few exceptions, there aren't many compact cameras with larger than normal pixels, and we would consider 1.5 microns and larger as being big for a compact camera. When you switch over to the next level up, the premium compact camera, you often find a larger sensor for improved image quality.

Panasonic Lumix TZ80 at ISO6400 (at 100%):

For more on compact cameras, have a look at our Top 10 Best Pocket Zoom cameras, or have a look at more compact camera reviews.

Premium Compact Camera – 1inch to APS-C sensors

With the introduction of a 1inch sensor in the Sony Cyber-shot RX100 in 2012, Sony introduced a compact camera with a larger than normal sensor, for improved image quality. Sensor sizes ranges from 1inch to APS-C in premium or advanced compact cameras, and more recently Full-Frame sensors have been used in compact cameras with a fixed lens. 

Here's a table showing a number of common premium camera resolutions, the sensor type, size, and pixel size in microns, along with a link to more details on each camera:

The 20 megapixel 1inch BSI sensor is used in a number of cameras, including the Sony Cyber-shot RX100 II, the Panasonic Lumix FZ1000, TZ100, and Canon Powershot G5X, G7X Mark II etc. The Sony Cyber-shot RX100 II has a bright variable aperture zoom lens, 2.4 micron sized pixels, and a 20mp BSI CMOS sensor. The 20 megapixel Micro Four Thirds sensor is larger, features 3.3 micron sized pixels, and APS-C sensors feature even larger pixels. For the largest pixel size there is the option of a Full-frame sensor, however, this also results in a larger camera, with larger lenses as well. 

Sony Cyber-shot RX100 II at ISO6400 (at 100%):

The increase in size of sensor from a compact camera to a 1inch sensor, has seen an impressive improvement in noise performance, with a sensor roughly 4 times larger than the typical compact camera. For more information on premium cameras with a larger sensor, have a look at the Top 10 Premium Serious Compact Cameras.

Micro Four Thirds and Four Thirds Sensors

When Olympus (and others) introduced the Four Thirds system, they used a smaller sensor size compared to APS-C, with a 2x crop factor, as they saw a benefit in creating a smaller camera system. In the beginning they suffered with noise performance, mostly due to the use of Kodak CCD sensors, but as time went on, the noise performance of Micro Four Thirds sensors began to catch up with APS-C sensors, and as the megapixel count of APS-C sensors increased further, the gap between them became less.

Here's a table showing a number of common Four Thirds and Micro Four Thirds resolutions, the sensor type, size, and pixel size in microns, along with a link to more details on each camera:

Four Thirds cameras used to offer a limited ISO range, however, this quickly changed with Micro Four Thirds cameras offering high ISO speeds.

Olympus OM-D E-M5 Mark II at ISO6400 (at 100%):

For more Micro Four Thirds cameras, have a look at the Top 13 Best Premium Mirrorless Cameras.

APS-C Sensors

The APS-C sensor varies in size depending on the camera it is in, with Canon APS-C sensors slightly smaller than other APS-C sensors. There are also APS-H sensors used in other cameras from Sigma and Canon. 

Here's a table showing a number of common APS-C camera resolutions, the sensor type, size, and pixel size in microns, along with a link to more details on each camera:

Note – for the most common resolution APS-C cameras, there is little difference in pixel size between a 24 megapixel APS-C camera (with a 3.9 micron pixel size) and a 16 megapixel Micro Four Thirds camera (with a 3.75 micron pixel size) – which should mean that ISO performance of both should be relatively similar (assuming sensor technology used in both is similar), although there is a slightly larger pixel on most 24mp APS-C cameras, and the sensor is also physically larger.

Comparing the Canon EOS 760D with a 24mp APS-C sensor, it has smaller pixels at 3.7 microns, compared to a 16mp Micro Four Thirds sensor, with 3.75 microns, which means that Micro Four Thirds cameras could in theory produce better noise performance than Canon’s sensors. (Due to Canon using smaller 1.6x crop APS-C sensors than other manufacturers).

Nikon D7200 at ISO6400 (at 100%):

For more Digital SLRs with APS-C sensors, have a look at the Top 10 Best APS-C Digital SLRs.

Full-Frame Sensors

Offering larger pixels, the Full-frame (FF) sensor is available in a number of resolutions, with popular cameras often offering a 24 megapixel sensor, which gives large 6.0 micron pixels, and often an extended ISO range going up to ISO51200. You can also go for a high resolution sensor, up to 50 megapixels, whilst still having relatively large 4.1 micron pixels. The Full-frame sensor is also capable of using the full image of a full-frame lens, something cameras with smaller sensors are unable to do (without additional adapters).

Here's a table showing a number of common full-frame camera resolutions, the sensor type, size, and pixel size in microns, along with a link to more details on each camera:

The full-frame sensor offers larger sensor size and larger pixel sizes than APS-C, and as the resolution increases the pixel size drops, but even the 50 megapixel sensor has larger pixels than a 24mp APS-C sensor. As the pixel size decreases, the ISO range available also tends to decrease, depending on how confident the manufacturer is in their noise reduction, noise performance, and sensor technology. The Canon EOS 5DS and 5DS R limit the maximum ISO speed to ISO12800, which is lower than the maximum ISO speed on a number of APS-C (and smaller) sensors.

If you want a camera that has large pixels, then you can go for a 12 megapixel full-frame sensor, with large 8.4 micron pixels, and on the Sony Alpha A7S (and Mark II) the ISO range can be extended up to 4 million ISO. 

Nikon D750 at ISO6400 (at 100%):

Canon EOS 5DS R at ISO6400 (at 100%):

For more full-frame Digital SLRs have a look at our Top 10 Best Full-Frame DSLRs.

Medium Format Sensors

Medium Format digital cameras often use different sized sensors depending on the resolution of the sensor available, and more recently have been using CMOS sensors instead of CCD sensors. Due to the expense of medium format sensors, as well as the low number of sales of medium format sensors, medium format sensors often seem to be some of the last sensors to benefit from technological advances in sensor technology.

Here's a table showing a number of common premium camera resolutions, the sensor type, size, and pixel size in microns, along with a link to more details on each camera:

Medium format cameras offer a larger sensor, but also a high resolution, which means that the priority isn't necessarily on low-light performance, as it is with some Full-frame cameras, but instead on high resolution. There are a number of CCD and CMOS sensors used in Medium Format cameras that have a limited maximum ISO speed, making them more suited to studio situations where you have control over light levels, and can ensure good lighting. The exception to this is the Pentax 645Z, which has a very high maximum ISO of ISO204800.

Pentax 645Z at ISO6400 (100%):

A note on image examples: These are from the JPEG images from the camera, so there will be differences in how each camera has processed the file, with each camera applying it's own strength of noise reduction. There are also differences due to the camera's white balance performance.

To calculate pixel size, you use the width of the sensor in millimetres divided by the image width in pixels, and multiply by 1000. Eg: 16mp Micro Four Thirds sensor, 17.3mm wide, divided by 4608, multiplied by 1000 (source).

Key Sensor Points:

• Larger sensors can collect more light, whilst also often featuring larger pixels
• Larger pixels improve light sensitivity - the larger the micron number, the better
• Backside illumination (BSI) sensors improve light sensitivity 
• A wider ISO range will also help in low light, and is often available with larger pixels
• Technological advances in sensor design and manufacture can massively improve image quality
• Newer sensors tend to perform better than older sensors

Additional information on sensor size, crop factors and technology:

• Guide to digital image sensor technology.
• Sensor size and crop factor.