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Convert power consumption to brightness output based on bulb technology
Lumens = Watts × Luminous Efficacy (lm/W)
Current efficiency: 90 lm/W (LED (90 lm/W))
| Power | LED (90 lm/W) | CFL (60 lm/W) | Incandescent (15 lm/W) |
|---|---|---|---|
| 5 W | 450 lm | 300 lm | 75 lm |
| 10 W | 900 lm | 600 lm | 150 lm |
| 15 W | 1,350 lm | 900 lm | 225 lm |
| 20 W | 1,800 lm | 1,200 lm | 300 lm |
| 40 W | 3,600 lm | 2,400 lm | 600 lm |
| 60 W | 5,400 lm | 3,600 lm | 900 lm |
| 75 W | 6,750 lm | 4,500 lm | 1,125 lm |
| 100 W | 9,000 lm | 6,000 lm | 1,500 lm |
| 150 W | 13,500 lm | 9,000 lm | 2,250 lm |
| 200 W | 18,000 lm | 12,000 lm | 3,000 lm |
Watts measure electrical power consumption while lumens measure actual light output. The relationship between them depends entirely on the bulb's luminous efficacy - how efficiently it converts electricity into visible light. LED technology revolutionized lighting by achieving 80-100 lumens per watt, compared to just 10-17 lm/W for incandescent bulbs. This means a 10W LED produces the same brightness as a 60W incandescent, reducing energy consumption by 83%. When shopping for bulbs, always check the lumens rating for brightness and watts for energy cost. Modern packaging displays both values along with "watt equivalent" references to help consumers transition from wattage-based thinking to lumens-based selection for accurate brightness comparison across technologies.
A 10W LED bulb produces approximately 900 lumens, equivalent to a 60W incandescent or 15W CFL. This represents an 83% energy reduction compared to incandescent technology while delivering the same brightness. The exact output varies by manufacturer and LED quality, with premium models achieving even higher efficiency.
No, you must know the bulb technology because luminous efficacy varies dramatically between types. A 20W LED produces 1,800 lumens while a 20W incandescent only produces 300 lumens - a 6x difference from the same wattage. Always check the bulb type or, better yet, read the lumens value directly from the packaging for accuracy.
LED efficiency varies based on chip quality, driver design, thermal management, color temperature, and manufacturing quality. Budget LEDs may achieve 70-80 lm/W while premium models reach 100-120 lm/W. Additionally, omnidirectional bulbs may have lower efficacy than directional designs due to optical losses. Always check the specific lumens rating rather than assuming wattage indicates brightness.
Yes, slightly. Warm white LEDs (2700-3000K) typically have 5-10% lower efficacy than cool white (5000-6500K) because phosphor coatings that create warm tones absorb some light energy. However, this difference is relatively minor compared to the technology type (LED vs. CFL vs. incandescent). For practical calculations, use the bulb's stated lumens rather than calculating from watts and assumed efficacy.
Smart bulbs typically have slightly lower efficacy (60-80 lm/W) compared to standard LEDs (80-100 lm/W) because additional electronics for WiFi, Bluetooth, or Zigbee connectivity consume power and generate heat. Color-changing smart bulbs have even lower efficacy (50-70 lm/W) when producing colored light, though white light mode performs similarly to standard smart bulbs.
Yes, LED lumens gradually decline over the bulb's lifetime due to LED degradation and phosphor aging. Quality LEDs maintain 70% of initial brightness after 25,000-50,000 hours (L70 rating). This degradation is gradual and imperceptible day-to-day. The wattage remains constant, meaning efficacy slowly decreases. Most users replace bulbs for other reasons before noticeable dimming occurs.