Milliwatt to BTU per Second Converter

How do I convert mW to watts or microwatts?

Formula:

• W = mW × 0.001 (or mW ÷ 1,000)
• µW = mW × 1,000

Examples:

• 1 mW = 0.001 W = 1,000 µW
• 100 mW = 0.1 W = 100,000 µW
• 1,000 mW = 1 W = 1,000,000 µW
• 10 mW = 0.01 W = 10,000 µW

mW to Watts converter →

What is a safe laser power in mW?

Laser safety classes:

Class 1 (< 0.4 mW): Inherently safe, cannot damage eye Class 2 (0.4-1 mW): Safe with blink reflex (~0.25 seconds) Class 3R (1-5 mW): Low risk with brief exposure, common laser pointers Class 3B (5-500 mW): Eye hazard, can cause injury Class 4 (> 500 mW): Severe eye and skin hazard, fire risk

Recommendations:

• Safe for general use: ≤ 1 mW (Class 2)
• Laser pointers (legal): < 5 mW in US (many countries limit to 1 mW)
• Avoid: > 5 mW for general use
• Industrial/medical: 10-10,000+ mW (requires safety training)

Example: 5 mW green laser appears ~30x brighter than 5 mW red laser to human eye (wavelength sensitivity).

How much power does a typical Bluetooth device use?

Bluetooth power classes:

Class 1: 100 mW (20 dBm) - Range: ~100 meters

• Use case: Industrial, long-range applications

Class 2: 2.5 mW (4 dBm) - Range: ~10 meters

• Use case: Most consumer devices (headphones, mice)

Class 3: 1 mW (0 dBm) - Range: ~1 meter

• Use case: Very low power, proximity devices

Bluetooth Low Energy (BLE): 0.01-10 mW

• Advertising: 0.01-1 mW (intermittent)
• Connected: 1-10 mW
• Deep sleep: 0.001-0.01 mW

Examples:

• Wireless earbuds: 2-10 mW (Class 2/3)
• Bluetooth speaker: 2.5-10 mW (Class 2)
• Fitness tracker: 0.1-5 mW (BLE)

What is dBm and how does it relate to mW?

dBm = Decibels relative to 1 milliwatt (logarithmic power scale)

Formula: dBm = 10 × log₁₀(mW)

Common conversions:

| dBm | mW | Description | |-----|-------|-------------| | 0 | 1 | Reference | | 3 | 2 | Double | | 10 | 10 | 10x | | 20 | 100 | 100x | | 30 | 1,000 | 1W | | -10 | 0.1 | 1/10 | | -20 | 0.01 | 1/100 | | -30 | 0.001 | 1 µW |

Why use dBm?

• Large ranges easier to express: -50 dBm to +30 dBm vs 0.00001 mW to 1,000 mW
• Simplifies gain/loss calculations (add/subtract vs multiply/divide)

Examples:

• Wi-Fi signal: -30 to -90 dBm (1,000 mW to 0.000001 mW)
• Cell tower: +43 dBm = 20,000 mW (20W)
• Bluetooth: 0 to +20 dBm (1-100 mW)

How long can a battery power a device using mW?

Formula: Battery life (hours) = (Battery capacity in mWh) ÷ (Device power in mW)

Example calculations:

CR2032 coin cell: 225 mAh @ 3V = 675 mWh

• LED (20 mW): 675 ÷ 20 = 34 hours
• Bluetooth beacon (1 mW avg): 675 ÷ 1 = 675 hours (~28 days)
• Watch (0.01 mW avg): 675 ÷ 0.01 = 67,500 hours (~7.7 years)

AA battery: 2,500 mAh @ 1.5V = 3,750 mWh

• LED flashlight (500 mW): 3,750 ÷ 500 = 7.5 hours
• Remote control (5 mW avg): 3,750 ÷ 5 = 750 hours (~31 days active)

Smartphone battery: 15 Wh = 15,000 mWh

• Idle (200 mW): 15,000 ÷ 200 = 75 hours (~3 days)
• Active use (2,000 mW): 15,000 ÷ 2,000 = 7.5 hours