A question we get asked every day: what size gobo do I need? The answer always comes down to your projector, but understanding why makes it much easier to get right the first time.
Why Gobo Size Matters
A gobo has to sit inside a metal holder in your fixture. If the disc is too large it won’t seat properly. If it’s too small it can shift or fall out of position, throwing your projection out of alignment mid-event.
Unlike most things you order online, there’s no forgiving margin here. A gobo that’s two millimeters off is a gobo you can’t use. This is why we ask for your projector model before production rather than after.
The Two Measurements That Matter
Outer Diameter (Gobo Size)
This is the full physical width of the disc, the measurement that determines whether it fits your fixture’s holder. When someone refers to a “Size A” or “Size B” gobo, they’re describing this measurement.
Inner Diameter (Max Image Size)
This is the usable area your artwork can occupy. The outer edge of the disc sits inside the holder, so a ring around the perimeter is covered and won’t project. Your design has to fit within the inner diameter.
This is where a lot of custom designs run into trouble. A logo that looks perfectly proportioned on screen may need to be scaled down to fit the projectable area, which is one of the things our team checks during artwork review.
Standard Gobo Sizes
Most fixtures (specially theatrical fixtures) use one of a handful of standard sizes:
- Size A — 100mm outer diameter, 75mm max image. Used in ETC Source Four and similar full-size theatrical fixtures.
- Size B — 86mm outer diameter, 64.5mm max image. The other common theatrical size.
- Size M — 66mm outer diameter. Found in Source Four Jr and comparable mid-size fixtures.
- Size E — 37.5 mm outer diameter. Found in many smaller size DJ projectors.
That said, most DJ and event fixtures don’t use lettered sizes at all. Moving heads, LED gobo projectors, and compact scanners typically use diameters between 20mm and 30mm that vary by model. For example a Chauvet Intimidator Spot 260 takes a 24mm disc, while a Chauvet Gobo Zoom LED takes 28.8mm.
How to Find Your Size
Three ways, in order of reliability:
- Look it up in our size chart. We maintain a reference table covering ADJ, Chauvet, Martin, Elation, ETC, G-lites, Robe, Vari-lite, and other fixtures with the exact size for each model.
- Check the manufacturer’s spec sheet. Gobo dimensions are usually listed under specifications or in the fixture manual.
- Measure the gobo already in the fixture. If there’s a stock gobo installed, pull it and measure across the widest point with calipers or a ruler.
Find your fixture in our full gobo size chart →
What If Your Projector Isn’t Listed?
We can cut any size, listed or not. Select “Other” in the size options when ordering and give us two numbers: the outer diameter (the full disc width) and the inner diameter (your maximum image area).
If you’re not sure how to measure, send us your fixture make and model and we’ll look it up or work it out with you before anything gets cut.
Renting Your Fixture?
If your DJ, venue, or AV company is supplying the projector, ask them for the exact make and model, not just “a gobo projector.” Two fixtures from the same brand can take completely different sizes, and this is the single most common reason a custom gobo arrives that doesn’t fit.
It’s worth asking early. Gobo production is fast, but there’s no fixing a sizing mistake on the day of an event.
Ready to Order?
Once you know your size, the rest is straightforward: upload your artwork or build a design in our gobo creator, and we’ll handle the review and production.
Still not sure what you need? Contact us with your fixture model and we’ll confirm the right size before you order.
