SNS画像サイズ一覧 (2026)そして無料のリサイズツール。

Instagram keeps your resolution as-is between 320 and 1080 pixels wide, so exporting above 1080 gains nothing on the feed.

“When you share a photo that has a width between 320 and 1080 pixels, we keep that photo at its original resolution as long as the photo's aspect ratio is between 1.91:1 and 4:5 (a height between 566 and 1350 pixels with a width of 1080 pixels).”

4:5 is the documented tall limit. Anything taller is cropped to fit.

“When you share a photo that has a width between 320 and 1080 pixels, we keep that photo at its original resolution as long as the photo's aspect ratio is between 1.91:1 and 4:5 (a height between 566 and 1350 pixels with a width of 1080 pixels).”

1.91:1 is the documented wide limit, which is why 566 is the height, not 608.

“When you share a photo that has a width between 320 and 1080 pixels, we keep that photo at its original resolution as long as the photo's aspect ratio is between 1.91:1 and 4:5 (a height between 566 and 1350 pixels with a width of 1080 pixels).”

Instagram does not publish a pixel size for organic Stories. 1080x1920 is the native full-screen render, not a documented requirement.

Safe zone: Profile icon at the top, call to action at the bottom (14% / 20%).

No Instagram page states a Story pixel size. The safe zone on this row IS official, from the Meta ads guide.

The 9:16 ratio is documented. The pixel size is not: 1080x1920 is the de facto export.

A cover that is not 9:16 is cropped to the middle 9:16 rectangle.

Safe zone: Profile icon at the top, call to action at the bottom (14% / 20%).

“The required aspect ratio is between 0.01:1 and 10:1, but the 9:16 aspect ratio is recommended to avoid cropping or blank space.”

Export square and keep the subject centred. Instagram publishes no dimension for this.

Safe zone: Cropped to a circle, so corners are always lost.

Instagram publishes no profile picture dimension.

The 720x1280 floor is documented. The 1080x1920 export is not: it is the native feed render everyone standardised on.

Safe zone: Action rail on the right, caption and handle along the bottom.

TikTok Studio documents a minimum upload resolution of 720x1280 and a 10 GB / 30 minute ceiling. No page states a recommended pixel size.

Safe zone: Cropped to a circle.

TikTok states the picture is cropped to a circle but publishes no dimension.

Google asks for 3840x2160, far above the size it is ever displayed at. Upload big: YouTube generates the small variants itself.

Safe zone: Duration badge sits bottom right; the progress bar covers the last strip once watched.

“Have a resolution of 3840 x 2160 pixels for videos and 2160 x 3840 for Shorts, with a minimum width of 640 pixels for videos.”

“Have a resolution of 3840 x 2160 pixels for videos and 2160 x 3840 for Shorts, with a minimum width of 640 pixels for videos.”

Safe zone: Cropped to a circle.

“Recommended dimensions for profile images are 400x400 pixels. Maximum file size for profile photos is 2MB. X supports JPEG, GIF, and PNG file formats.”

Safe zone: The avatar overlaps the lower left; the layout crops the height on narrow screens.

“Recommended dimensions for header images are 1500x500 pixels.”

X does not publish a size for organic post images. It states that single photos between 2:1 and 3:4 display in full, which is the constraint that actually matters.

Ratio behaviour is documented; the pixel size is a de facto convention.

400x400 is the documented floor, not a recommendation. Going larger is fine up to 7680x4320.

Safe zone: Cropped to a circle.

“Pixel size is between 400 (w) x 400 (h) pixels and 7680 (w) x 4320 (h) pixels. Maximum file size is 8MB. File type must be PNG or JPG.”

Safe zone: The avatar and the name block sit over the lower left.

“Recommended pixel dimensions are 1584 (w) x 396 (h) pixels.”

“All images must be PNG or JPEG files and have a maximum size of 3MB.”

Unusually wide. A design built for a 4:1 profile banner will not survive this crop.

“All images must be PNG or JPEG files and have a maximum size of 3MB.”

“Use a 1.91:1 ratio (1200 x 627 pixels). Image must be more than 200 pixels wide.”

Displayed at 820x312 on desktop and 640x360 on mobile, so the two crops differ. Keep anything important in the middle.

Safe zone: The profile photo overlaps the lower left on mobile.

Values read from the Meta Help Center page: cover recommended 851x315 (sRGB JPG under 100 KB), displayed 820x312 on desktop and 640x360 on mobile, minimum 400x150. Summarised, not transcribed.

Displayed at 176x176 on desktop and 196x196 on mobile, so 320x320 gives the retina headroom.

Safe zone: Cropped to a circle.

Page profile picture: recommended 320x320, displayed 176x176 desktop, 196x196 mobile, 36x36 feature phones.

Below 600x315 the card falls back to a small square thumbnail instead of the wide image.

“Use images that are at least 1200 x 630 pixels for the best display on high resolution devices. The minimum allowed image dimension is 200 x 200 pixels. The size of the image file must not exceed 8 MB.”

Pins outside 2:3 are truncated in the feed rather than letterboxed.

“We recommend using a 2:3 aspect ratio, or 1000 x 1500 pixels.”

“Aspect ratio is 9:16, but there are no restrictions for image or video. 1080x1920 pixel size (9:16 ratio).”

Snapchat specifies 720x1280 for ads, which is lower than the 1080x1920 most tools assume.

Safe zone: Top bar and the swipe-up call to action.

Snapchat lists 720x1280 at 9:16 for Single Image or Video Ads, Story Ads and Collection Ads. Summarised from the ad-formats page, not transcribed.

Snapchat publishes no dimension for organic Snaps. Match the ads spec or the 9:16 full-screen frame and check it in the app.

No open Snapchat page states a size for organic Snaps.

Meta publishes no Threads image spec. Threads does not force a crop on organic posts: anything from square to 9:16 is shown as uploaded.

Because nothing is cropped, pick the ratio for the content rather than for the platform.

No Meta page publishes Threads image dimensions. The profile picture is inherited from the linked Instagram account rather than set on Threads.