GU10 Bulb Size Guide

GU10 Bulb Size Guide

GU10 Bulb Size Guide

GU10 Bulb Size

No official GU10 measurement exists. However, many modern GU10 LEDs now comply with a standard 53 mm height and 50 mm width. The issue stems from early GU10 LED bulbs, which contained a large LED driver and subsequently differed in length from halogen counterparts. Retrofitting halogen GU10s for energy-saving modern LED alternatives is now commonplace. 

However, the design of some GU10 bulbs takes purpose-specific light fitting sizes into account. Always read the product description to ensure you purchase the GU10 size relevant to your needs.

Examples of GU10 bulb sizes include:

GU10 Bulb Type 


Height (length)

PAR16 (Standard) 

50 - 51 mm

50 - 55 mm

PAR 36

111 mm

58 - 66 mm

PAR 20

63.5 mm

64 - 89 mm

PAR 28 

120 - 121 mm

134 - 136 mm

Remember, some of the above GU10s designs have a specialist functionality. In most domestic and commercial settings, GU10 bulbs come in standard sizing (including LED).

What is a GU10 Bulb?

A GU10 bulb has a bi-pin base. Small ‘feet’ protrude at a 90-degree angle from each pin, giving the GU10 its distinctive look.

Common uses for GU10 bulbs:

  • Security Lighting 
  • Recessed domestic lighting
  • Decorative or accent lighting 
  • Commercial display lighting (e.g., commercial product lighting)

GU10 bulbs typically serve recessed lighting purposes. Heat hotspots can appear behind some bulbs in enclosed spaces. However, GU10 LED bulbs run at significantly cooler temperatures compared to competitor bulbs. Lower running temperatures and less energy consumption make LED GU10s ideal for domestic and commercial lighting solutions.

Will My Existing Home Fittings Accommodate GU10 LED Bulbs?

Modern GU10 LED bulbs offer a “perfect” or “true” fit with existing home light fittings. Consumers looking to retrofit any existing halogen GU10s with LED GU10 bulbs should not run into difficulties. Older LED bulbs were longer than alternative halogen solutions. The reason for this was the presence of an internal LED driver encased within the LED unit.  

However, although the LED driver unit remains inside the bulb, technology has caught up, and bulb sizes have reduced to a competitive standard length.

There are two considerations concerning GU10 bulb sizes:

  • Surface-mounted fittings

Surface-mounted fittings include any lighting fixture that sits proud of the wall or ceiling. The length of the bulb should not matter when dealing with surface-mounted fittings. Bulb height is a consideration regarding a ‘flush’ finish (see below).

  • Recessed lighting (maintaining a flush appearance)

Recessed lighting fixtures look best when they appear flush to the ceiling. If you have concerns about GU10 sizing, compare the depth of your recessed lighting fixture to the length of the bulb stated in the product description.

Benefits of GU10 LED Bulbs

GU10 LED bulbs use less energy for the same light output as competitor halogen bulbs. GU10 LEDs also last around ten to twenty times longer than incandescent and halogen alternatives.

By witching to GU10 bulbs, you can save upwards of 80% on your lighting bills. You will also benefit from the less frequent hassle of replacing your bulbs.

How to Choose GU10 Beam Angle

The beam angle describes the ‘cone’ of light that shines down from the bulb. There are three considerations regarding beam angle and purpose:

Beam Angle

Uses (domestic & commercial)

25 degrees

Narrow spotlighting, used in task zones and for product lighting.

36 - 40 degrees

Medium cone. 40-degrees is the most common home lighting choice.

60 degrees (and above)

Wide-angle. Used in general domestic and commercial lighting scenarios. 

Conclusion - How to Choose the Correct GU10 Bulb Size

As we know, there is no official GU10 bulb size. If you are unsure, assume your standard home lighting fixtures will accommodate GU10 bulb dimensions of 53 mm in height and 50 mm in width. But for certainty, always take the time to measure your fittings and check the product specifications.