storage (photos)

Though 13GB for 1800 Photos seems at higher side. Do you have Live Photos?

If you are comparing the storage size with respect to you friend's photo storage then...

The amount of storage consumed by photos can vary based on factors such as the file format, resolution, compression, and other data associated with the photos.

1. Your friend's photos may be smaller than yours. The size of a photo can vary depending on the resolution, the file format, and the compression settings. If your friend's photos are smaller than yours, they will take up less storage space. Take Apple ProRAW photos with your iPhone camera
2. Your friend may have turned on iCloud Photos. iCloud Photos is a feature that allows you to store your photos and videos in the cloud. This means that your photos are not actually stored on your iPhone, but rather on Apple's servers. If your friend has turned on iCloud Photos, their photos will not take up as much storage space on their iPhone. Optimize Photo Storage: Enable the "Optimize iPhone Storage" option in the Photos settings. This feature will automatically store lower-resolution versions of your photos on your device while keeping the full-resolution versions in iCloud. This can help save storage space. Tap Settings > [your name] > iCloud > Photos. Tap Sync this iPhone. In iOS 15 or earlier, tap to turn on iCloud Photos. Select Optimize iPhone Storage to save space on your device. Manage your photo and video storage - Apple Support (IN)
3. If your photos have a higher resolution, they will occupy more storage space. Higher-resolution photos capture more details but require more storage. Using HEIF or HEVC media on Apple devices
4. The file format of the photos can also impact storage usage. For example, if your photos are saved in a lossless format like TIFF or RAW, they will occupy more space compared to compressed formats like JPEG.
5. If you have a significant number of videos or Live Photos in your collection, they can take up substantial storage space compared to static images. Take and edit Live Photos
6. The iPhone model can also impact the amount of storage consumed by photos. Different iPhone models may have varying camera capabilities, which can result in differences in file sizes and storage usage. For example, newer iPhone models often feature higher megapixel cameras and improved image processing capabilities, which can lead to larger file sizes for photos. Additionally, newer models may support advanced features like Deep Fusion or Night Mode, which can result in larger file sizes for certain photos that utilize these features. On the other hand, older iPhone models with lower-resolution cameras or less advanced image processing capabilities may produce smaller file sizes for photos. Identify your iPhone model and check the spec here --> iPhone Tech Specs - Apple Support And iPhone - Shopping Help - Apple