What is a vector file? A plain-English guide
A vector file stores artwork as shapes described by math: points, the lines and curves that connect them, and the colors that fill them in. Because it’s a set of drawing instructions rather than a grid of dots, it can be redrawn at any size, from a business card to a billboard, and the edges stay perfectly sharp.
That’s why printers, sign shops and embroidery companies ask for one. They need artwork they can scale up, split into colors, or cut along the edges without anything going blurry.
Vector vs. raster
Most images you deal with every day are raster images. A photo, a screenshot, a JPG or a PNG is a grid of tiny colored squares called pixels. The grid has a fixed number of squares. Make the image bigger and each square just gets bigger, so the edges turn blocky or soft.
A vector logo has no pixels at all until something draws it. Ask for it at 2 inches wide and it’s drawn at 2 inches. Ask for it at 20 feet and it’s drawn again, just as cleanly, at 20 feet.
Edges stay smooth at any size.
You start to see the squares (pixels).
| Vector | Raster | |
|---|---|---|
| Made of | Shapes and curves | Pixels |
| Common file types | AI, EPS, SVG, and PDF (sometimes) | JPG, PNG, GIF, WebP, HEIC, TIFF, PSD |
| Make it bigger | Stays sharp | Gets blocky or blurry |
| Change a color | Easy: recolor the shape | Hard: every pixel has to change |
| Best for | Logos, icons, lettering, signs, apparel, engraving | Photos, screens, social posts |
Why printers ask for vectors
Different shops need vectors for different reasons:
- Screen printers and promo-product companies separate a design into one screen or plate per color. Solid, clean-edged shapes make that easy. Pixels with soft, blended edges don’t.
- Vinyl cutters, sign shops and laser cutters have a machine follow the outline of each shape. A picture has no outlines to follow.
- Large-format printers may need to blow a logo up to banner or vehicle size, far beyond what most image files can stretch to.
- Embroidery digitizers turn artwork into stitches. They can work from a picture, but clean shapes give them a far better result.
If you send a picture instead, the shop usually has to redraw your logo, which costs time and often a fee.
The file extension doesn’t prove it
AI, EPS, PDF and SVG are vector formats. That means they’re able to hold vector shapes. They can also hold a photo, or a pasted-in JPG of your logo, and nothing on the outside of the file tells you which.
A JPG saved as a PDF is still a JPG on the inside. A PNG dropped into Illustrator and saved as .ai is still a PNG. This is the most common reason “but I sent you a vector!” turns into a back-and-forth with a printer. We explain it in more detail in fake vector files.
When a raster file is fine
You don’t need a vector for everything. A raster image works well on websites, social media and slides, and it can print well too, as long as it has enough pixels for the size you’re printing.
The rule of thumb is 300 pixels for every inch of print for a sharp result. Around 150 pixels per inch, edges start to look soft. So a PNG that’s 3,000 pixels wide will print sharp up to about 10 inches wide, and look acceptable up to about 20. When you check a raster file with the checker, it does this math for you and tells you the largest size that will look sharp.
How to check what you have
Zooming in on an edge is a decent first test: a vector stays smooth, a raster shows squares. It can’t spot a picture hiding inside a vector file, or a logo that was auto-traced, though. For four ways to check, see how to tell if your logo is a vector, or just run it through the checker.