Most YouTube views happen on phones, where thumbnails are tiny. Check your thumbnail text for length and colour contrast, and see a live preview at full size and at phone size.
- Free to use
- No sign-up needed
- Works on phone and desktop
How to use the thumbnail checker
- Type the text you plan to put on your thumbnail.
- Pick your text and background colours.
- Look at the phone-size preview. If you can’t read it easily, nor can your viewers.
- Work through any amber items in the checklist.
Thumbnail text tips
- Use five words or fewer. The image should do most of the work.
- Aim for a contrast ratio of at least 4.5:1 so text stands out.
- Use a bold, simple font and add an outline or shadow on busy backgrounds.
- Don’t repeat your title. Use the thumbnail to add curiosity or context.
Frequently asked questions
What is a contrast ratio?
It measures how different two colours are in brightness, from 1:1 (no contrast) to 21:1 (black on white). Higher is easier to read.
What size should a YouTube thumbnail be?
YouTube recommends 1280 × 720 pixels (16:9). The preview uses the same shape.
Does this upload or store my design?
No. It only previews your text and colours in your browser.
More free tools
See all tools →🎬YouTube Transcript GeneratorGet the full transcript of any captioned YouTube video, with or without timestamps.Open tool →📺YouTube Title & Description CheckerPreview and check your video title, description, hashtags and chapters before you publish.Open tool →🎥YouTube Video Ideas GeneratorTurn one topic into 20 video title ideas using formats viewers already click on.Open tool →⏱️Video Script TimerSee how long your script will take to say, and how many words fit your target length.Open tool →
Use every tool without daily limitsAll Tools Pro gives you unlimited use of every tool for £9 a month + VAT. Cancel any time.
See All Tools Pro