When taking pictures with our phones, most of us don’t even think about the actual size of the photos we’re taking. That is until the phone warns us we’re running out of memory. Only then we worry about how much space our photos occupy.
How big are mobile photos? The size of a photo depends on many factors but mainly the sensor and number of megapixels it has. The more megapixels, the larger the resolution and, ultimately, the larger you can print the image in photo quality. More resolution also means a bigger file size. However, two images with the same resolution can have different file sizes depending on the format and contents of the picture.
What affects the file size of smartphone photos?
Unless it’s the exact same shot, no two images captured by the same camera are ever the same file size. This could be because of the contents of the photograph or the settings of the camera.
At the very core of what affects the size of mobile photos is the design of the camera, particularly the sensor and the number of megapixels on it.
Megapixels
The term ‘megapixels’ means 1 million pixels. These pixels are individual squares that make up an image. For example, a 12MP image is made up of 12 million pixels. The higher the megapixel count, the more detailed the image is. This not only means a bigger file size, but also a larger physical print.
Here’s basically what this means: A 12MP image has a resolution of about 4000 x 3000 pixels in width and height. This would give you a photo-quality print of approximately 13×10” and an approximate .jpeg file size of ~3MB.
The sensor
Megapixels aren’t the “be-all and end-all” of the factors that affect file size. The size of the sensor also plays a part because it determines how many pixels the sensor can accommodate, and how big the pixels can be.
A big sensor with large pixels can receive a lot more light information than a small sensor with tiny pixels. All that information captured by the sensor means more space will be required.
The detail
The amount of detail that is in the picture does add to the overall file size. If you take a photo in a low-light condition or against nothing but a solid colour, there isn’t much light information or colour variation in the shot so the resulting file size will be small.
On the other hand, bright pictures with a lot of colour and intricate detail will definitely yield larger file sizes because there’s a lot more light information of varying intensities coming through that needs to be processed.
The file format
Not all smartphones have support for more than one file format for photos other than jpeg. However, some phones give you an option to either shoot jpeg or RAW. If you choose to shoot RAW, then the file size of your photos will be significantly larger.
Jpeg vs RAW file size
These two file formats have their own distinct qualities that affect the file size (not resolution).
As previously mentioned, jpeg is the most popular format that is used in pretty much every camera phone on the market. When your smartphone is set to save in .jpeg (or .jpg) format, the image is automatically processed and compressed to an optimum size and tosses out any extra data. The result is a very decent, optimised, high-quality picture with a small file size.
RAW (DNG) files are as the name suggests— raw. These type of files are quite large and bulky because, unlike with jpeg, they aren’t automatically processed. Therefore, they remain uncompressed and retain all the picture data that a .jpeg file would’ve otherwise stripped away. This allows for more flexibility in post-processing.
Because it is uncompressed and unprocessed, a RAW file can be roughly three times or more the size of a jpeg. For example, if an average photo taken with a 12MP smartphone camera is ~3MB (megabytes) in .jpeg format, it is possible that the same picture in RAW format could be as large as ~19MB.
The folks at Toolstud.io have a very handy megapixel calculator you can use to give you a rough idea of how large in megabytes (MB) a photo can be given its resolution from calculating its megapixels (MP) and file format.
Is there a way to reduce the MB size of a photo without losing quality?
An easy way to quickly and easily reduce the file size or even resolution of a picture is to use a third-party app like Photo & Picture Resizer for Android. This app allows you to easily reduce photo size without any apparent loss of quality. You can use it before uploading your images online or sending loved ones your photos via email or text. It’s convenient and super simple to use.
Desqueeze available on iPhone does pretty much the same function. Not only does it easily resize photos, it does the same for videos as well. It can output images in a variety of formats for both photos and videos without a hassle. What’s more, it allows batch resizing, which I think is pretty cool.
If your pictures are on your computer and you would like to resize them from there, a quick Google search for online picture resizing will give you endless options of sites where you can upload your picture and have it automatically resized or enter your own specifications. ResizeImage is a good example of such a site.
Messenger apps such as WhatsApp and email clients like Gmail are known to compress images that are sent via their platform. The loss of quality on the resized photo is not so apparent on the phone screen but you won’t get as large a print from it as you would have from the original photo.
How large can you print your photos?
There are many factors that influence how large you can print your smartphone photos but the main one is the actual resolution of the photos. The higher the resolution, the larger the print.
To find what size you can print a photo, you need to divide each dimension of the resolution by the PPI (pixel per inch) quality you wish to print. 300ppi gives you photo quality prints while 200ppi can still give you good quality. Anything 150 and below is low quality and may make the pixels visible when looking at the images.
For example, a smartphone with a 12MP resolution camera will produce a print of 14” x 9” at 300ppi, 21” x 14” at 200ppi, and 26” x 16” at 150ppi.
Keep in mind that as much as printing at 150ppi allows you to print larger pictures, the photos aren’t as sharp as they would be if they were printed smaller at 300ppi. It’s important to understand PPI (pixels per inch) and not confuse it with DPI (dots per inch), especially if you’re looking to print your own photos from home.
It’s worth noting that cropping and editing your photos with some third-party apps such as Instagram may affect the size and resolution of your photo. I recommend using pro level apps and software to shoot and edit your photos and retain their original size.
Conclusion
So, does size matter? I’d say it does, depending on your needs. If you’re a serious smartphone photographer who sells prints of their work, then you’d probably want to shoot RAW at a higher resolution. If that’s the case, expect large file sizes.
But if you’re the average Joe then you don’t really need to shoot RAW. You don’t even need to shoot at a high resolution. An 8MP. jpeg is more than enough to post on social media or text to friends and family. And at an estimate file size of about 2MB, you will have even more space on your device.
This article first appeared on my other blog thesmartphonephotographer.com. Check it out!
