How Many Watts Does a Light Bulb Use?
ZacharyWilliamIf you have ever looked at a bulb and saw “9W LED = 60W” or “12V 5W RV bulb” and wondered what it really means for your power bill or for your portable power station, this guide will walk you through exactly that.
1. What this article will answer
This post focuses on the homeowner/RV/camping search intent: “how many watts does my light bulb use, and what should I buy if I want it to be bright but not waste power?” We will compare LED, CFL, halogen, and old incandescent bulbs, and we will also show how long a light can run on a battery (using real UDPOWER capacities).
2. What is “watt” for a light bulb?
A watt (W) is how fast the bulb uses electrical energy. More watts = more power draw. It’s not brightness by itself. Modern LED bulbs can use only 8–10 W but match the brightness of an old 60 W incandescent bulb because LEDs are more efficient.
Remember: brightness is measured in lumens, energy consumption is in watts. A good LED gives you more lumens per watt.
3. Typical wattages by bulb type
Below is a reference table you can drop into a camping/RV blog or a home-energy article.
| Bulb type / use | Common wattage (120V or 12V) | Matches old incandescent | Notes |
|---|---|---|---|
| LED bulb (home) | 4–6 W (small rooms), 8–12 W (main rooms) | 8–10 W LED ≈ 60 W incandescent | Best for off-grid, cool running, long life. |
| LED smart bulb | 7–11 W | Similar to 60 W incandescent | May draw a tiny standby load for Wi-Fi. |
| CFL bulb | 9–14 W | 13 W CFL ≈ 60 W incandescent | Now less popular than LED. |
| Halogen | 28–72 W | Lower than classic incandescent | Brighter, but still warm/hot. |
| Incandescent (classic) | 40–100 W commonly | Baseline everyone knows | Easy to calculate, but power-hungry. |
| 12 V RV LED / camper dome light | 3–5 W | Enough for interior space | Great for battery systems. |
| Outdoor/party LED string | 1–2 W per bulb (or 10–20 W per strip) | — | Scale by number of bulbs. |
So, when someone asks “how many watts does a light bulb use?”, the most accurate answer is: modern home LEDs use around 8–12 W, while old bulbs used 60 W to show the same brightness.
4. Why does wattage differ so much?
Three simple reasons:
- Technology: LED > CFL > halogen > incandescent in efficiency.
- Brightness level: a 100 W-equivalent LED will use more than a 40 W-equivalent LED.
- Supply voltage and environment: 12 V RV bulbs are optimized for batteries, so they sip power.
Color temperature (warm vs daylight) doesn’t meaningfully change watts for LEDs made by the same brand/series.
5. How to calculate electricity/cost
Use this formula:
Energy (kWh) = (Wattage × Hours Used) ÷ 1,000
Example: a 10 W LED on for 5 hours = 10 × 5 ÷ 1,000 = 0.05 kWh. If your rate is $0.15/kWh, that’s 0.05 × 0.15 = $0.0075. Practically nothing.
Do the same for older 60 W bulbs: 60 × 5 ÷ 1,000 = 0.3 kWh → 0.3 × 0.15 = $0.045. Now multiply by all bulbs in the house – that’s why people convert to LED.
6. If you run bulbs on a portable power station
This is where campers, RV users, and people preparing for outages really care. Let’s take real capacities from UDPOWER and estimate how long they can run lights. We apply an 85% usable-energy factor to stay realistic.
| Light load | Power draw | UDPOWER S1200 (1,190 Wh) |
UDPOWER C600 (596 Wh) |
UDPOWER C400 (256 Wh) |
UDPOWER C200 (192 Wh) |
|---|---|---|---|---|---|
| Single LED bulb (5 W) | 5 W | ≈ 202 h | ≈ 101 h | ≈ 44 h | ≈ 33 h |
| Two LED bulbs (10 W) | 10 W | ≈ 101 h | ≈ 50 h | ≈ 22 h | ≈ 16 h |
| LED string / small tent light (20 W) | 20 W | ≈ 50 h | ≈ 25 h | ≈ 11 h | ≈ 8 h |
| Old 60 W incandescent | 60 W | ≈ 16.8 h | ≈ 8.4 h | ≈ 3.6 h | ≈ 2.7 h |
As you can see, lighting is a very “battery-friendly” load. Even the smallest UDPOWER units can keep lights on through the night, while the S1200 can keep a family’s essential lighting on for days.
7. UDPOWER options for lighting backup
Below are real products from the UDPOWER site, matched to the light-bulb use case. Recommendation is intentionally lightweight — lighting does not need a huge inverter, but higher capacity means longer backup.
S1200 Portable Power Station
1,190 Wh LiFePO₄, 1,200 W output, up to 1,800 W surge. Ideal if lighting is just one of the loads (fans, router, small fridge, CPAP). Also supports UPS <10 ms for sudden outages.
C600 Portable Power Station
596 Wh, 600 W rated, 1,200 W surge, 5-year warranty — very good middle ground for RV or balcony backup where you want lights + a few devices.
C400 Portable Power Station
256 Wh, 400 W rated, up to 800 W max — enough for indoor LED lighting, a router, and phone charging.
C200 Portable Power Station
192 Wh, 200 W pure sine wave, 400 W surge — perfect as an emergency “lamps + phone + one more gadget” pack.
If you want to stay off-grid longer, pair any of these with UDPOWER’s 120 W portable solar panel to refill during the day. That makes lighting almost “free” as long as you get sun.
8. Quick FAQ
Is 60 W a lot?
For old bulbs, 60 W was the standard. For LED, 60 W equivalent is only about 9–10 W now.
Does brightness change wattage?
Yes — brighter bulbs draw more watts, but LED scales very efficiently.
What about 220 V regions?
The bulb will be specified for the local voltage, but the stated wattage is always the power it uses. A 10 W LED is 10 W whether it’s 120 V or 220–240 V, assuming it’s designed for that voltage.
Can I run a whole room’s lights on a small power station?
Yes. A room with five 9 W LEDs is only 45 W. Even a 192 Wh unit can give you several hours of light.
