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Gigawatt to Milliwatt Converter

Convert gigawatts to milliwatts with our free online power converter.

Quick Answer

1 Gigawatt = 1000000000000 milliwatts

Formula: Gigawatt × conversion factor = Milliwatt

Use the calculator below for instant, accurate conversions.

Our Accuracy Guarantee

All conversion formulas on UnitsConverter.io have been verified against NIST (National Institute of Standards and Technology) guidelines and international SI standards. Our calculations are accurate to 10 decimal places for standard conversions and use arbitrary precision arithmetic for astronomical units.

Last verified: February 2026Reviewed by: Sam Mathew, Software Engineer

Gigawatt to Milliwatt Calculator

How to Use the Gigawatt to Milliwatt Calculator:

  1. Enter the value you want to convert in the 'From' field (Gigawatt).
  2. The converted value in Milliwatt will appear automatically in the 'To' field.
  3. Use the dropdown menus to select different units within the Power category.
  4. Click the swap button (⇌) to reverse the conversion direction.
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How to Convert Gigawatt to Milliwatt: Step-by-Step Guide

Converting Gigawatt to Milliwatt involves multiplying the value by a specific conversion factor, as shown in the formula below.

Formula:

mW = GW × 1000000000000

Example Calculation:

1 GW = 1000000000000 mW

Disclaimer: For Reference Only

These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.

Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.

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What is a Gigawatt and a Milliwatt?

1 GW = 1,000,000,000 W = 1,000 MW = 1,000,000 kW = 1,341,022 hp = 3.412 billion BTU/h

1 mW = 0.001 W = 0.000001 kW = 1,000 µW (microwatts)

Note: The Gigawatt is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Milliwatt belongs to the imperial/US customary system.

Common Uses and Applications: gigawatts vs milliwatts

Explore the typical applications for both Gigawatt (imperial/US) and Milliwatt (imperial/US) to understand their common contexts.

Common Uses for gigawatts

Power Plants: Nuclear reactors, coal plants, large hydro dams (1-3 GW each). National Grids: Total generation capacity for countries/regions. Energy Policy: Renewable energy targets, grid expansion planning. Data Centers: Massive hyperscale facilities (approaching 1 GW).

When to Use milliwatts

Lasers: Pointer lasers (1-5 mW), barcode scanners (1-10 mW). Wireless: Bluetooth (1-100 mW), Wi-Fi (10-1,000 mW), RFID tags. Medical: Hearing aids (1 mW), pacemakers (50-100 µW standby). Electronics: LEDs, sensors, low-power circuits.

Additional Unit Information

About Gigawatt (GW)

How do I convert GW to MW or kW?

Formula:

  • MW = GW × 1,000
  • kW = GW × 1,000,000
  • W = GW × 1,000,000,000

Examples:

  • 1 GW = 1,000 MW = 1,000,000 kW
  • 2.5 GW = 2,500 MW = 2,500,000 kW
  • 0.5 GW = 500 MW = 500,000 kW

GW to MW converter → GW to kW converter →

How much power is 1.21 gigawatts?

Reference: "Back to the Future" flux capacitor requirement

1.21 GW = 1,210 MW = 1,210,000 kW

Equivalent to:

  • ~1 nuclear reactor at full output
  • ~600 large wind turbines (2 MW each)
  • ~400,000 US homes' average consumption
  • ~1,620,000 horsepower
  • Lightning bolt peak: ~1 TW (1,000 GW) for microseconds, but 1.21 GW sustained is massive

Reality: No practical way to extract 1.21 GW from a lightning bolt (too brief, unpredictable)

How many homes can 1 GW power?

Average US home: ~1.2 kW average draw (30 kWh/day ÷ 24 hours)

1 GW = 1,000,000 kW

Calculation: 1,000,000 kW ÷ 1.2 kW/home ≈ 833,000 homes

Regional variations:

  • Southwest US (high AC use): ~600,000 homes per GW
  • Northeast US: ~700,000-800,000 homes per GW
  • Pacific Northwest: ~900,000-1,000,000 homes per GW

Peak vs average: During peak demand (hot summer afternoon), 1 GW powers fewer homes (~300,000-500,000).

What is the world's largest power plant?

Three Gorges Dam (China): 22.5 GW capacity

  • Type: Hydroelectric
  • Turbines: 34 generators
  • Annual generation: ~100 TWh/year
  • Location: Yangtze River

Other massive plants:

  • Itaipu Dam (Brazil/Paraguay): 14 GW
  • Xiluodu Dam (China): 13.86 GW
  • Belo Monte Dam (Brazil): 11.23 GW
  • Guri Dam (Venezuela): 10.2 GW

Largest nuclear (single site): Kashiwazaki-Kariwa (Japan): 7.97 GW (7 reactors)

How do countries measure their energy capacity?

Installed capacity: Total GW of all power plants (nameplate rating)

Actual generation: Lower than capacity due to:

  • Capacity factor: % of time at full output
  • Maintenance downtime
  • Fuel availability
  • Grid demand

Example - US (2024):

  • Installed capacity: ~1,200 GW
  • Peak demand: ~740 GW (summer)
  • Average demand: ~450 GW

Capacity factor by source:

  • Nuclear: 90-95% (runs constantly)
  • Coal: 40-60%
  • Natural gas: 30-60%
  • Wind: 25-45%
  • Solar: 15-30%

About Milliwatt (mW)

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

Conversion Table: Gigawatt to Milliwatt

Gigawatt (GW)Milliwatt (mW)
0.5500,000,000,000
11,000,000,000,000
1.51,500,000,000,000
22,000,000,000,000
55,000,000,000,000
1010,000,000,000,000
2525,000,000,000,000
5050,000,000,000,000
100100,000,000,000,000
250250,000,000,000,000
500500,000,000,000,000
1,0001,000,000,000,000,000

People Also Ask

How do I convert Gigawatt to Milliwatt?

To convert Gigawatt to Milliwatt, enter the value in Gigawatt in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our power converter page to convert between other units in this category.

Learn more →

What is the conversion factor from Gigawatt to Milliwatt?

The conversion factor depends on the specific relationship between Gigawatt and Milliwatt. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.

Can I convert Milliwatt back to Gigawatt?

Yes! You can easily convert Milliwatt back to Gigawatt by using the swap button (⇌) in the calculator above, or by visiting our Milliwatt to Gigawatt converter page. You can also explore other power conversions on our category page.

Learn more →

What are common uses for Gigawatt and Milliwatt?

Gigawatt and Milliwatt are both standard units used in power measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our power converter for more conversion options.

For more power conversion questions, visit our FAQ page or explore our conversion guides.

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Other Power Units and Conversions

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Verified Against Authority Standards

All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.

NIST Reference on Constants, Units and Uncertainty

National Institute of Standards and Technology — Fundamental physical constants and unit conversions

BIPM SI Units

Bureau International des Poids et Mesures — International System of Units (SI) definitions and standards

ISO 80000

International Organization for Standardization — Quantities and units international standards series

Last verified: February 19, 2026