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Step 3: Choose brightness

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Lumens to Watts

More Watts doesn’t always mean a brighter light bulb. To choose a light bulb with the right brightness, think lumens, not Watts.

In the past, if you wanted a brighter bulb you’d simply choose one with more Watts. For example, most 75 W bulbs – irrespective of brand – put out about the same amount light.

However, today’s light bulbs are so much more energy efficient, they use fewer Watts to produce the same amount of light (lumens). This is why nowadays you need to think lumens, not Watts, when buying light bulbs.

For example, you can have the same brightness from an old 60 W incandescent (which has since been phased- out) from a halogen using 42 W, CFL using about 13 W – or an LED using just 10 W.

To choose a replacement bulb with the same brightness as your old one, take it with you to the shop and match it up. If you’d like to learn more about buying a bulb based on brightness – and what the difference is between lumens and Watts – read on.

Explore this page to learn:

  • what is a Watt
  • lumens and light – getting it right
  • efficiency – maximum brightness from minimum energy
  • how to convert Watts to lumens.

Fast facts

$12

How much more it costs each year to run each 1100 lm halogen bulb in living areas, instead of an equivalent LED

80

The lumens per watt (lm/W) of an efficient LED – compared to 14 lm/W of an equivalent halogen. Higher lm/W means more energy efficient… and cheaper to run

800

How many lumens (lm) an old 60W incandescent bulb puts out – the same brightness as a 42 W halogen, 13 W CFL or 10 W LED  

What is a Watt?

Back in the day we bought incandescent bulbs based on Wattage – if we wanted a brighter bulb we’d choose one with more Watts.

However Watts are not a measure a brightness, they’re a measure of energy consumption – that is, how much electricity a bulb uses. It just so happened that most old incandescent bulbs of the same wattage put out the same amount of light (lumens), even when they’re from different brands.

Today’s light bulbs can produce the same amount brightness using far less electricity – which makes them much cheaper to run.

For example, a 42 W halogen bulb has the same brightness (lumens) as an LED that uses just 10 W. Lower wattage means lower energy bills – and less carbon emissions. Better for your wallet and better for the environment.

The more energy efficient the light bulb technology, the less electricity (Watts) a bulb uses. This means you can’t compare the brightness of light bulbs by how many Watts they use. You need to compare the lumens they put out.

What can I use Watts for?

Watts are no longer relevant when comparing the brightness of light bulbs, but they’re still important when considering energy efficiency.

When comparing two bulbs of the same brightness (lumens), the one with the lowest Wattage on the box will be cheaper to run. This is because more efficient light bulbs waste less energy to produce the same amount of light – they consume less electricity. The energy efficiency of light bulbs is measured in lumens per Watt (lm/W) – the higher the better!

Lumens and light – getting it right

If you are looking for the right amount of light (brightness), think lumens, not Watts.

Lumens give a measure of the amount of light – the brightness – produced by a light bulb. Whether it’s a CFL, LED, halogen, fluoro or incandescent bulb, the bigger the number, the brighter the bulb.

How many lumens do I need?

If you want a brighter light bulb, choose one with more lumens.

If you aren’t sure how many lumens you need to suits your space – and are still accustomed to buying bulbs by Wattage – you can use the conversion table below to work it out.

‘Equivalent’ Watts

Some light bulb packages display an ‘equivalent’ Wattage figure. This refers to incandescent bulbs. For example, an 1100 lm LED may state it's equivalent to – in brightness – a 75 W incandescent. However, a quality LED uses as little as 11 W of energy to produce this, making it a lot more efficient. 

Energy efficient light bulbs – more lumens, less Watts

The most efficient energy saving lights produce the most light (lumens) using the least electricity (Watts).

Energy efficiency in lighting products is given in lumens per Watt (lm/W) – the higher the number, the more energy efficient.

For example, an old-fashioned incandescent light bulb – which is no longer available in Australia since the phase out – produced 1100 lm and used 75 W of power, which is 15 lm/W. A halogen lamp producing the same lumens uses 52 W, which is 21 lm/W – the halogen is more efficient.

While you can source the brightness (lumens) you need from a range of light bulb types and technologies, a quality LED is generally the most energy efficient. To see how much energy (in Watts) different bulb types use to produce the same light output (lumens), use the conversion table below.

Convert lumens to Watts

The lumens to Watts conversion table below shows the number of lumens (and Watts) you should look for in a replacement LED, CFL or halogen light bulb. Lumen values are approximate and can vary between manufacturers.

Output (lumens)

Power (Watts)

 

Traditional Incandescent

Halogen (mains Voltage

CFL

LED

250

25

18

4-6

3-4

500

40

28

7-9

5-8

800

60

42

11-14

8-12

1100

75

52

14-17

11-17

1500

100

70

19-23

15-23

The Light Bulb Saver app

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Download the app

The Light Bulb Saver app makes it easier to work out what kind of bulb to buy, while showing how much you could save by choosing a more efficient bulb. Download the free app now from iTunes or Google Play.