If you’ve still to upgrade your halogen spotlights to LED, time is running out.

In September 2016, the European Commission directive banning the manufacture of ‘high-energy’ halogen spotlights came into force. These light bulbs are now becoming increasingly difficult to find as retailers sell through the last of their stock. This guide will tell you everything you need to know about replacing Halogen MR16 light bulbs with LED light bulbs.

Fortunately, upgrading Halogen MR16 light bulbs to LED is usually a painless affair, as most LED light bulbs are now designed to retrofit to existing light fittings. All you have to do to swap your old light bulbs out is remove them from the light fixture and fit the new, shiny light bulbs in their place.

The same goes for low voltage spotlights, but as they use transformers to convert mains voltage to a suitable lower one, you have to be careful to install the right LED light bulbs.

Replacing Halogen MR16 light bulbs with LED light bulbs

If you have low voltage halogen light bulbs installed with a transformer, the first thing you need to do before replacing Halogen MR16 light bulbs with LED light bulbs is to find the transformer’s maximum load. You should be able to find this on the body of the transformer itself, in the form of a ‘VA’ number. This VA number will either be fixed, or it will be a range (e.g. 10-60VA).

These numbers tell you the maximum wattage that the transformer can carry. For example, a 40VA transformer can handle up to a 40-watt halogen light bulb, while a 10-60VA one can carry between 10 and 60 watts worth of light bulbs. Some transformers might just carry one individual light bulb, while others might be able to carry several lower wattage light bulbs in a series.

At this point, it’s important to note that if it is a halogen transformer, this maximum load applies to halogen light bulbs only. For example, if you have a 40VA transformer for halogen light bulbs, you should not install 40-watts worth of LED light bulbs. This would overload the fitting and potentially cause a safety issue.

Fortunately, there is an easy way to find the right low voltage LED spotlights.

Equivalent wattage – swapping halogen MR16 light bulbs for LED

The natural energy-saving properties of LED light bulbs means that they can offer the same brightness of a halogen equivalent, but using only a fraction of the power. A 5W LED spotlight, for example, can offer the same brightness of light as a 35W halogen spotlight.

The 5W LED light bulb is the ‘equivalent wattage’ of the 35W halogen light bulb. You can usually find this equivalent wattage listed with online product details, specification sheets (where available), and on the product packaging.

When replacing Halogen MR16 light bulbs with LED light bulbs, it’s important to use LED light bulbs of equivalent wattage to your existing halogen light bulbs. This will ensure that the transformer can still handle the load safely.

For example, if you have one 35W halogen installed in your kitchen, ensure you swap it for 35W equivalent LED. The actual wattage of the LED light bulb may vary, but the equivalent wattage must be the same as your current halogen light bulbs. For example, you might find both 5W and 6W LED light bulbs that have an equivalent wattage of 35W; both of these would be fine to replace 35W halogen light bulbs.

This is only getting more complicated as LED technology gets ever more energy-efficient, but as long as you remember to look for the equivalent wattage, you will find the right LED spotlights. We’ve finished our guide off below with a quick ‘cheat sheet’ to help you remember all the technical terms discussed above. See our in-depth glossary of lighting terms for even more information.

Equivalent Wattage

A term used to compare LED light bulbs with their incandescent alternatives. An LED light bulb with an equivalent wattage of 35W is a direct replacement for a 35W incandescent light bulb. This is different from a light bulb’s stated wattage (see below).

Halogen MR16 Spotlights

Spotlights are ‘directional’ light bulbs that emit light in a focused beam. Halogen spotlights are a form of incandescent light bulb that use a tungsten filament and a mix of inert and halogen gases to produce light. The European Commission directive in September 2016 banned the manufacture of this type of power-hungry spotlights.

LED Spotlights

LED (light-emitting diode) light bulbs are the most technologically advanced and energy-efficient light bulbs available. They last many times longer than halogen light bulbs, produce the same amount of light, but use only a fraction of the energy. Most LED light bulbs can be used with existing light fittings (this is called retrofitting).

Low Voltage

Most light bulbs operate off mains voltage (see below), but some light fittings are designed to be lower voltage. These are most commonly used in integrated kitchen fittings, where space is at a premium and smaller light bulbs are a necessity. Low voltage light fittings often need a compatible transformer (see below) to convert mains voltage to the correct, lower voltage. Most low voltage spotlights will be between 12-24 volts.

Mains Voltage

The voltage of a building’s electrical circuits. in the UK mains voltage was 240 volts until late in the 20th Century, when it was changed to 230V to match other European countries. As this comes with a +10% tolerance, electrical equipment with a stated voltage of 240V is still fine to use on standard UK mains circuits. The majority of light bulbs are for use with mains circuits, except for ‘low voltage’ light bulbs, which must be used with a compatible transformer (see below). All low voltage light bulbs should be clearly stated as such on product listings and packaging.


Bulbs that operate on a lower voltage than 230-240V must be used with a compatible transformer when installing on UK mains circuits. The transformer converts mains voltage to a lower voltage suitable for the light bulbs, ensuring they function as designed and preventing damage to the light bulbs and/or light fittings.

VA rating

The volt-ampere (VA) rating is the maximum load (in watts) that a transformer can safely carry. For example, a 40VA transformer can handle up to 40-watts of electrical equipment, while a 10-60VA one can carry between 10 and 60 watts worth. Installing low voltage LED light bulbs on a transformer designed for halogen lighting requires you to find the equivalent wattage (see above) for the LED light bulbs, so as not to overload the transformer.

Wattage (or Stated Wattage)

Denotes the rate of power consumption of electrical equipment. A higher wattage equals greater power consumption. LED light bulbs have a stated wattage and lumen output, as well as an equivalent wattage (see above).

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[…] Replacing Halogen MR16s With LEDs – Everything You Need to Know to Make the Switch […]

John Dowell
John Dowell
March 11, 2020 7:05 pm

I have 2 gu4 halogen bulbs in my fireplace. I’ve tried to replace with two led bulbs. When I install the new led bulbs they dont work. If I leave one led bulb in and install 1 halogen bulb in the led light lights up. The halogen bulb does not.

Why is this ?

Norman Dunbar
Norman Dunbar
April 13, 2020 1:18 pm
Reply to  John Dowell

Sounds like the load on the transformer isn’t high enough to keep the power on. I have a similar problem. Apparently you can either “put a load resistor” on the output or keep one halogen bulb in the circuit. Kind of defeats the purpose of replacing with LEDs!

Mat @ Lightbulbs Direct
April 14, 2020 10:05 am
Reply to  Norman Dunbar

Norman is correct – the transformer in the fireplace is not designed to work with LED’s – many transformers need a minimum load to work, such as 50W, which is fine when you have two 28W halogen light bulbs installed. But when you replace with LED, the light bulbs may be only 2W or 3W and this is not enough to work with the transformer. You could contact an electrician and see if they could replace the transformer that is in the fireplace. We sell a LED driver that could be installed instead. Alternatively – stock up on GU4 MR11… Read more »

March 17, 2020 11:11 am

I have high voltage halogen bulbs installed with a transformer. Do I need to change the transformer if I want to retrofit new LED lights into existing fixtures?

Mat @ Lightbulbs Direct
March 17, 2020 1:26 pm
Reply to  Pawan

What voltage is high voltage?

The LED light bulbs we sell operate on a UK standard 240V AC, and the light bulbs have a built-in transformer to change this 240V to the LED required voltage.
We also sell 12V light bulbs, but these need to be used in conjunction with a 12V transformer.

Tom Kilgllen
Tom Kilgllen
March 26, 2020 10:17 pm

The LED bulbs I bought seem as though they will be fine in my current MR16 housings. The existing lights are running through a Low voltage dimmer.
My question is – I would think I need to leave the low voltage dimmer instead of switching it to an LED dimmer. As far as I know, a standard LED dimmer is not low voltage. Do they even make an LED low voltage dimmer? Do I need it?

Thank you!!

Mat @ Lightbulbs Direct
March 28, 2020 12:09 pm
Reply to  Tom Kilgllen

Hi Tom, this very much relies on the quality of your transformer. The dimmer switch acts by cutting the power on/off very rapidly, but it is down to the response of the transformer in how this is relayed to the MR16 lights. My only advice is to take advantage of a supplier’s returns policy to try some products out on your own set-up. Remember to keep the packaging in a re-saleable condition and understand that you will probably have to cover the cost of return postage if you order from an online retailer.

April 15, 2020 3:36 pm


Peter Chappell
Peter Chappell
May 5, 2020 11:03 am

I intend to replace all my Halogen MR16 Dichroic spotlights as I am fitting covers in the loft and need aluminium reflectors or the heat build up is too great. Good opportunity to replace with LED spots. Are these equivalent to aluminium reflectors and do not allow heat to emit from the back of the light?

Mat @ Lightbulbs Direct
May 6, 2020 8:48 am
Reply to  Peter Chappell

Yes and no, well, not in the same way. Dichroic reflectors have a coating which reflects all visible light and IR light (heat) forwards out of the front of the lamp; and as they are halogen lamps, they generate ALOT of heat. LED are different in that they don’t generate that much heat in the first place. Typically most LED’s are cool enough to touch even after being run for many hours. I don’t think you would find much problem using LED MR16’s under a loft hood, especially some of the newer models which are even lower power than the… Read more »

Eric Atkinson
Eric Atkinson
May 29, 2020 12:44 pm

I am wishing to replace halogen light bulbs in my shower room with LED ones, I am finding that the LED bulbs are strobing after a few minutes of being switched on. Do I need to change the transformer?

Mat @ Lightbulbs Direct
May 29, 2020 4:48 pm
Reply to  Eric Atkinson

It is likely that the transformer cannot be replaced, as a shower fitting should be water-tight for obvious safety reasons. I would advise replacing the whole spotlight to a waterproof (IP65) rated fitting with an integrated LED, which would eliminate this strobing problem plus give you confidence that you have a safe product to use. We have a range of ceiling downlights suitable for bathrooms – https://www.lightbulbs-direct.com/indoor-lighting/application/bathroom/. Something like the Phoebe LED Firesafe is a great choice as it comes with inter-changeable bezels (white, chrome, brushed nickel), is fully dimmable, and has a switch under the bezel so you can… Read more »

June 8, 2020 4:05 am

Hello.. Is it possible to replace Type T 40W Halogen Bulb in a lamp to a LED light? Would appreciate your answer!

Mat @ Lightbulbs Direct
June 10, 2020 1:31 pm
Reply to  Maria

Yes, you can swap an Halogen Type T for LED, but they are quite hard to find LED versions. We stock a range of halogen ones if you cannot find one: https://www.lightbulbs-direct.com/shop-by/shape/tubular/#?Category0=Shop+By&Category1=Shape&Category2=Tubular&Customfieldshape=T45%5ETubular&Customfieldtechnology=Halogen%5EIncandescent%5ELED&search_return=all

August 21, 2020 7:37 pm

currently have 21 (old 30 watt) halogen spots, 3 to a transformer. Can I just change to led GU 5 bulbs or do I have to remove transformers ?

Mat @ Lightbulbs Direct
August 28, 2020 11:32 am
Reply to  Rose

This depends on the capabilities of the halogen driver. As halogen consumes much more power than LED, the driver may not support lower powered lightbulbs. Never fear, as we stock a replacement 12V driver for LED lightbulbs.

October 2, 2020 7:57 pm

If you replace to an LED driver do you need to change the old dimmer switch on the wall though?

September 25, 2020 6:38 pm

I have a HiSpec HSE60L transformer. It says 60W max on with SEC: 11.8V~eff. I’m wanting to change to LED bulbs. There were 3 bulbs installed and now I have 1 left. When talking about the equivalent, does this mean each bulb can only be a maximum of equivalent 60W overall (I.e. equivalent 20w each) or can it be equivalent 60W per bulb?

Mat @ Lightbulbs Direct
October 9, 2020 9:12 am
Reply to  DV

It means the wattage of all the bulbs added together (not equivalent), if there’s 3x LED bulbs @ 5W each, then that = 15W. However, I cannot find any information on this specific driver, so I’m not sure if it is LED compatible or not.

October 9, 2020 12:58 pm

Thank you

September 28, 2020 5:11 pm

I currently have down lights with Osram decode 51s (12V 50W) halogen bulbs. Each light has a dimmable 60VA transformer connected. Could you please advise on a suitable replacement dimmable LED bulb?
I guess an alternative would be to fit new GU10 lamp holders with LED bulbs and ditch the transformers. Do you think thy is would be a better approach?
Many thanks

Mat @ Lightbulbs Direct
October 9, 2020 9:16 am
Reply to  David

We still stock Osram 12V MR16 halogen spotlights but we also stock replacement LED dimmable MR16 spotlights – the choice is yours really.

Chris Perry
Chris Perry
October 5, 2020 5:33 pm

Hi. I’m looking to replace low voltage (12v( halogens with 240v LEDs) because of the problems I’ve had with transformers and replacement 12v LEDs. I will remove the transformers from the circuits, so a 240v feed to the bulb. Can I use the existing GU5.3 (MR16) sockets? Will the 240v LEDs still be more energy efficient?
Thanks for your help

John Hopper
John Hopper
October 10, 2020 9:09 pm

I had 3 xhalogen 50w mr16 bulbs run by a 150w transformer. Will led mr26 bulbs work the same