Yes you can and it is highly recommended as they will be more energy efficient as they require less wattage than the halogen versions to produce the same amount of light.

MR11 refers to a particular type of reflector bulb that has a diameter of 35mm and it has two sharp pins that are spaced 4mm apart.  This is sometimes referred to as a GU4 base.  The majority of MR11s are 12V and the LED replacements have been designed with this in mind running on 12V as well.  Manufacturers of these LED bulbs have also focused on designing these bulbs to be the same shape and design as their halogen counterparts allowing for them to work as replacements easily within the same fitting.

Key Advantages of LED MR11s

Below is a comparison table between halogen and MR11 bulbs, highlighting the many benefits in changing to LED:

Can I Just Swap Halogen Bulbs for LED?

In most cases you can but you will need to make sure the replacements are 12v and to check that the LED bulbs will be compatible with your transformer/driver as this may not be able to operate the lower wattage of the LED replacement part.

The Transformer Challenge (Low-Voltage Systems)

Halogen MR11 fixtures use a transformer to step down the mains household voltage (240V) to the 12V needed for the bulb. There are two common types of 12V transformers:

1. Magnetic (Wire-Wound) Transformers

This older style of transformer generally works well with LED bulbs.  But you will need to check that your dimmer switch is compatible with the LED bulb.  This should be advised by the type of dimming your bulb and dimmer operate on.  It will be listed as something like “0-10V dimming” or “constant voltage dimming.”

2. Electronic Transformers

This type of transformer is often designed to require a minimum electrical load to function correctly. This is where issues can arise; your transformer may be rated for 20W-60W for example.  This would work for 3 x halogen 20W bulbs but would not be compatible for 3 x 3-4W LED bulbs.  If you were to use these lower wattage bulbs with the transformer in this example it could cause the transformer to flicker or not even turn on at all. 

To Conclude

You can replace halogen MR11 bulbs with LED bulbs but you will need to make sure they are compatible with your transformer.  If it is a magnetic transformer you will just need to make sure the bulb is 12v but if it is an electronic transformer you will need to check the wattage of the transformer and make sure the total wattage of the bulbs adds up to the minimum wattage load for the transformer.  You will also need to make sure your dimmer switch is compatible if you are looking to dim the bulbs and this will apply to both types of transformer.