YouTube thumbnail preview

What this thumbnail preview does

This tool shows your YouTube thumbnail and title in the places a viewer will meet them: the desktop home grid, the suggested sidebar, a search result, a phone feed and a TV home row. You can drop up to three versions and see them side by side in every one of those places.

Use it before you publish, while you can still change the design. A thumbnail is drawn large and judged small. The question is whether it still reads when it is a few centimetres wide, in grey, out of focus, or across a living room. The image never leaves your browser: it is read on your device and nothing is uploaded.

This page checks a design you already have. To build one, start with how to make a YouTube thumbnail in our free course, or look through the thumbnail examples.

How to use it

1. Drop your thumbnail on slot A. You get the file check: pixel size, ratio, file size and type, each compared with YouTube's published spec.
2. Type your title, channel name and video length. You get the title under each thumbnail with the real line limit of that surface, and a list of the surfaces where it is cut.
3. Read the legibility tests. You get the thumbnail blurred (the squint test), in grayscale, and at the smallest size. If you cannot name the subject in all of them, simplify the design. The lesson on faces and contrast shows what survives.
4. Look at the length badge. You see what the bottom-right corner loses. Move any word or face out of it. For how many words a thumbnail can carry, see text on YouTube thumbnails.
5. Switch between dark and light mode. You see whether the edges of the thumbnail melt into either background.
6. Set the couch view. Enter your TV size and couch distance. You get the TV row at the size it appears from the couch, and the maths behind it.
7. Add versions B and C. You get all three next to each other on every surface, so you can pick the one that survives. To let viewers decide, read thumbnail A/B testing.

YouTube's thumbnail spec

These are the only numbers on this page that come from YouTube. Source for every row: YouTube Help, "Add video thumbnails on YouTube", checked October 2026.

Rule	What YouTube says
Recommended resolution	A YouTube video thumbnail should be 3840 x 2160 pixels.
Minimum width	A YouTube video thumbnail must be at least 640 pixels wide.
Aspect ratio	A YouTube video thumbnail should be 16:9. Shorts thumbnails are 9:16 and podcast playlist thumbnails are 1:1.
File format	YouTube asks for thumbnails in image formats such as JPG or PNG.
File size on mobile	A video thumbnail uploaded from the mobile app can be up to 2 MB.
File size on desktop	A thumbnail uploaded on desktop can be up to 50 MB.

The full list of YouTube limits lives on the YouTube specs reference.

How big a thumbnail is on screen (our measurements)

YouTube does not publish display sizes, and the layout stretches with the window. We measured the live site ourselves on 5 October 2026: signed out, Chrome on macOS, reading the rendered size of the thumbnail image and the style of the title. Treat these as what we saw that day, not as a spec. YouTube tests new layouts often, and signed-in pages, other browsers and the mobile app can differ.

Surface	Thumbnail	Title
Desktop home grid	Measured at a 1440 px wide window: three per row, 373 x 210 px. At 1920 px wide it was 533 x 300 px, at 1280 px wide 376 x 211 px.	16 px text, cut after 2 lines.
Desktop suggested sidebar	Measured at a 1440 px wide window: 248 x 139 px. At 1280 px wide it was 267 x 150 px, at 1920 px wide 367 x 206 px. Many guides quote 168 x 94 px, which we did not see in October 2026.	14 px text, cut after 3 lines.
Desktop search result	Measured at 1440 px and 1920 px wide windows: 500 x 281 px in both.	18 px text, cut after 2 lines.
Mobile home feed	Measured on the mobile website (m.youtube.com) at a 390 px wide phone viewport: full width, 390 x 219 px. The mobile app was not measured and may differ.	14 px text, cut after 2 lines.
Length badge	20 px tall and 32 to 48 px wide depending on the length, 8 px in from the bottom-right corner (4 px in the sidebar at 1440 px wide).	12 px text.
TV app	Not measured. The TV row in this tool is an approximation.	Not measured.

Many guides state that the sidebar thumbnail is 168 x 94 pixels. We could not reproduce that figure in October 2026, where the sidebar was 248 to 367 pixels wide. We keep 168 x 94 in the legibility tests as the harshest case.

Why the TV matters

Our guide to making YouTube videos for TV covers the whole living-room audience. The short version for thumbnails follows.

"TV has surpassed mobile and is now the primary device for YouTube viewing in the U.S. (by watch time)", wrote YouTube's CEO Neal Mohan on 11 February 2025 (YouTube Official Blog, checked October 2026). That is a statement about watch time in one country, not about where every click happens. It is still a good reason to look at your thumbnail from the couch.

The couch maths

Something looks the same size when it fills the same angle of your vision. So the tool keeps the ratio of width to distance the same:

• TV width = diagonal x 16 / √(16² + 9²), which is diagonal x 0.8716 for a 16:9 screen.
• Angle = 2 x atan(TV width / 2 / couch distance).
• Width on your screen = TV width x (your distance from this screen / couch distance).
• Pixels = that width in inches x your screen's pixels per inch (96 unless you calibrate).

The calibration bar uses the short edge of a bank card, which is 53.98 mm under the ID-1 format of ISO/IEC 7810 (Wikipedia summary of the standard, checked October 2026).

A worked example

You have a 55 inch TV and a couch 3 metres from it. You are sitting 60 cm from a monitor.

1. TV width: 55 x 0.8716 = 47.9 inches, which is 121.8 cm.
2. Angle from the couch: 2 x atan(60.9 / 300) = 22.9 degrees.
3. Width on your monitor: 121.8 x 60 / 300 = 24.4 cm.
4. At 96 px per inch: 24.4 / 2.54 x 96 = 920 px.
5. With four thumbnails across the TV, each one is about 199 px wide on your monitor.

So from the couch, each thumbnail on that TV looks smaller than the 248 px sidebar thumbnail we measured on a desktop. A big screen does not mean a big thumbnail.

The tone numbers

For each thumbnail the tool shrinks the image to 168 x 94 pixels and measures the lightness of every pixel from 0 (black) to 100 (white). It reports the distance between the dark areas and the light areas (1st to 99th percentile, so a small bright word still counts) and the lightness of the outer edge. Luminance uses the sRGB formula in WCAG 2.2 (checked October 2026), converted to CIE L* lightness.

The hints attached to those numbers are our own rule of thumb: under 30 points of range we call the image flat, and an edge within 15 points of the page background may blend into it. These are not YouTube rules and they do not predict clicks. Trust your eyes on the blurred tile first.

What this tool does not do

• It does not predict click-through rate or score your thumbnail. Nobody can honestly do that from a picture.
• It does not show real videos next to yours. The neighbours are grey placeholders, so it cannot tell you how you compare with a specific competitor.
• It does not reproduce YouTube pixel for pixel. Sizes are our measurements, the font may differ from the one on your device, and the TV row is an approximation.
• It does not judge your title. For length and wording, use the title checker.
• It does not keep your images. Your title and settings are remembered in this browser, your thumbnails are gone when you close the tab.

Vanpelt Studio, the desktop app, goes one step further and reviews the thumbnail and title together against what the video promises. This page only shows you the picture in place.