Before ordering a replacement or custom gobo, confirm three separate dimensions: its outer diameter, usable image area and thickness. Start with the exact projector model and its documentation. A measurement from an existing gobo can help, but the outside diameter alone does not establish compatibility.
This guide explains what each dimension means and what to send for a size review. It does not replace your projector’s instructions or provide a universal cross-brand fit chart.
Three dimensions, three different jobs
| Dimension | What it describes | What to confirm |
|---|---|---|
| Outer diameter (OD) | The overall diameter of the physical disc | Required diameter and any specified tolerance |
| Image area (IA) | The area available for the design on the gobo | The permitted image diameter or artwork template |
| Thickness | The depth of the gobo, viewed from the edge | Accepted thickness for the material and holder |
Concept diagram only. The relative sizes and edge thickness are illustrative, not a product specification.
The image area on the gobo is not the size of the image on your wall or floor. Those are separate measurements: artwork must fit the gobo’s permitted image area, while the projected result also depends on the projector’s optics and setup.
1. Identify the projector and holder first
Record the manufacturer, full model name and any model revision shown on the label. Find the manual or manufacturer’s gobo specification. If the fixture has different holders or gobo wheels, identify the one being used.
Look for the required outside diameter, image area, accepted material and thickness. Record any tolerances exactly as given; do not round a dimension just to match a nearby product option.
A letter size or a familiar-looking disc is a useful starting point, but it is not the complete specification. The holder and material requirements still need to match.
2. Check the outer diameter of an existing gobo
If you already have a compatible spare or a gobo that can be removed according to the manufacturer’s instructions, its dimensions can provide a useful cross-check. Disconnect power and allow the equipment to cool as directed before handling it. If removal requires unfamiliar disassembly, use the manual or ask for support instead.
Measure across the center of the complete disc, from one outside edge to the opposite edge. A suitable caliper can provide a clearer reading than estimating against a ruler; use gentle contact and protect the coated surfaces. Do not squeeze, bend or scrape the disc.
Write the result in millimeters and label it outer diameter. Also state whether you measured the bare disc or an assembly with a ring or carrier. A carrier’s overall size is not automatically the bare gobo size.
If you only have a ruler measurement, mark it as approximate. Send it as supporting information rather than treating it as a manufacturing dimension.
3. Get the permitted image area from the specification
The visible logo on an existing gobo may occupy only part of the available image area. Measuring that logo does not tell you the maximum permitted artwork size.
Use the fixture documentation or an approved artwork template to establish the usable image area. If it is missing, request confirmation before finalizing the artwork. Do not calculate it by subtracting an assumed border from the outer diameter.
For a narrow wordmark, record the artwork’s width and height as well as the permitted image area. The design needs to fit within that area; it does not have to fill every part of it. For file formats and preparation, use our gobo artwork checklist.
4. Confirm thickness separately
Two gobos with the same outer diameter may still have different thicknesses or holder requirements. An existing disc’s thickness is useful evidence, but it does not reveal the holder’s full permitted range.
Where the manufacturer allows measurement of a removed disc, use an appropriate instrument and avoid damaging its surfaces. State whether any ring or mounting assembly is included in your reading. If the part is difficult to measure safely, send the specification or request guidance instead.
Do not assume that a thinner disc is automatically suitable, or force a replacement into a holder. Diameter, thickness, material and retention requirements need to be checked together.
5. Choosing a GoboSolution size
Our Custom Logo Gobos page lists 37.5 mm, 53 mm and Custom Size options. Use that page’s current model guidance when selecting for a GoboSolution projector.
For a third-party projector, a matching diameter is not sufficient confirmation. Send the exact model and available specifications for review before selecting a standard option. Keep unknown image-area or thickness requirements marked as unknown rather than substituting values from a different brand’s size chart.
Your compatibility-review checklist
Gather these details before ordering:
- Projector manufacturer, exact model and a clear label photo.
- Manual page or manufacturer specification for the gobo and holder.
- Required outer diameter, image area and thickness, with units and tolerances where stated.
- Permitted material and any holder, carrier or wheel details.
- Existing gobo measurements and photos, clearly marked as measured or approximate.
- Your artwork file and any dimensions that remain unconfirmed.
If you do not have an existing gobo, start with the model label and manual. You do not need to guess missing dimensions to make an inquiry.
Request a compatibility review with the information you have. Once the requirements are confirmed, return to the custom gobo options to select the appropriate size and material.