Lumens to Watts Converter

The Lumens to Watts Converter turns a brightness in lumens into the equivalent wattage for four common bulb technologies — LED, CFL, halogen, and incandescent — so you can see exactly how much power each one needs to produce the same light. It also estimates the yearly energy cost of each option and how much you save by switching to LED, making it easy to pick the right bulb without guessing.

Lumens vs Watts: What is the Difference?

Lumens (lm) measure brightness — the total amount of visible light a bulb gives off. Watts (W) measure power — how much electricity the bulb consumes. For decades we shopped for bulbs by watts because, with old incandescent bulbs, more watts always meant more light. Modern LEDs broke that link: an LED can be just as bright as an old 60-watt bulb while drawing under 10 watts. Today, lumens tell you how bright a bulb is, and watts tell you how much it costs to run.

Lumens to Watts Formula

To convert lumens to watts you divide by the bulb's luminous efficacy — the number of lumens it produces per watt of power:

Because each technology has a different efficacy, the same brightness maps to very different wattages. This converter uses these representative mid-range efficacy values:

• LED — about 90 lm/W (most efficient)
• CFL — about 60 lm/W
• Halogen — about 20 lm/W
• Incandescent — about 15 lm/W (least efficient)

Real products vary a little around these figures, so treat the results as close, practical estimates rather than exact ratings.

Lumens to Watts Conversion Chart

These are the brightness levels people commonly recognize, with the approximate watts each bulb type needs to produce them. The "old bulb" column shows the traditional incandescent wattage most shoppers still think in.

How Much Light Do I Need?

Choose a bulb by the lumens the space needs, then pick the lowest-watt technology that delivers them. As a rough guide:

• Under 250 lm — night lights, closets, and accent lighting.
• 250–450 lm — bedside lamps, hallways, and mood lighting.
• 450–800 lm — table lamps and general living-area bulbs.
• 800–1100 lm — kitchens, bathrooms, and reading lamps.
• 1100–1600 lm — large rooms, garages, and task lighting.
• Over 1600 lm — workshops, retail spaces, and outdoor floodlights.

Why LED Bulbs Save So Much

An incandescent bulb wastes roughly 90% of its energy as heat, producing light almost as a by-product. LEDs convert far more of their power into visible light, so they hit the same lumens with a fraction of the watts. For the same brightness, an LED typically uses about 80–85% less electricity than an incandescent bulb, runs cooler, and lasts many times longer — which is why the savings add up quickly across a whole home.

What Affects a Bulb's Efficiency?

How to Use This Calculator

1. Choose your input: Select whether you know the lumens (brightness) or an old incandescent watt rating, then enter the value.
2. Set optional cost details: Adjust your electricity price per kWh and daily hours of use to estimate running costs.
3. Click Convert: The tool calculates the equivalent watts for LED, CFL, halogen, and incandescent bulbs.
4. Compare the results: Review the wattage cards, comparison bars, annual costs, and LED savings, plus a step-by-step breakdown.

Frequently Asked Questions

How do you convert lumens to watts?

Divide the lumens by the bulb's luminous efficacy in lumens per watt: Watts = Lumens / Efficacy. Because each technology has a different efficacy (roughly 15 lm/W for incandescent, 20 for halogen, 60 for CFL, and 90 for LED), the same brightness needs very different wattages. For example, 800 lumens is about 9 watts of LED but about 53 watts of incandescent.

How many watts is 800 lumens?

800 lumens is roughly 9 watts for an LED bulb, 13 watts for a CFL, 40 watts for a halogen, and about 53 watts for a traditional incandescent bulb. 800 lumens is the brightness people usually associate with an old 60-watt incandescent.

What is luminous efficacy?

Luminous efficacy is how much visible light a bulb produces for each watt of power it uses, measured in lumens per watt (lm/W). A higher efficacy means more light for less electricity. LEDs have the highest efficacy of common household bulbs, which is why they use far fewer watts than incandescent bulbs for the same brightness.

Are lumens or watts more important when buying a bulb?

Lumens matter more for brightness. Watts measure power consumption, not brightness, so with modern LEDs a low-watt bulb can be very bright. When shopping, choose the lumens you need for the room, then pick the bulb type with the lowest watts to save energy.

How much can I save by switching to LED?

LEDs typically use about 80 to 85 percent less energy than incandescent bulbs for the same brightness. Over a year of normal use, a single bulb can save several dollars, and swapping all the bulbs in a home can cut lighting electricity costs dramatically while lasting far longer.

Do lumens change with bulb type?

No. Lumens measure the actual brightness that reaches your eyes, so 800 lumens looks equally bright whether it comes from an LED, CFL, halogen, or incandescent bulb. What changes between bulb types is the wattage needed to produce those lumens.

Additional Resources

• Luminous Efficacy - Wikipedia
• Lumen (unit) - Wikipedia