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The Ergs per Second to Watts Converter converts power from ergs per second (erg/s) to watts (W), milliwatts (mW), and kilowatts (kW) using the exact conversion factor 1 erg/s = 10⁻⁷ W. The erg is the energy unit of the centimeter-gram-second (CGS) system, and erg/s is its corresponding power unit.
The CGS system was the dominant system in physics for over a century before the SI system was adopted internationally in 1960. While SI (using joules and watts) is now standard, the CGS system and its erg unit persist in several fields: astrophysics (stellar luminosity), spectroscopy (radiation flux), geophysics (seismic energy release rates), and older physics literature that has not been updated to SI units.
The conversion is straightforward: the erg is defined as 1 g·cm²/s², while the joule is 1 kg·m²/s². Since 1 kg = 1000 g and 1 m = 100 cm, the ratio is 1000 × 100² = 10⁷, giving 1 J = 10⁷ ergs and 1 W = 10⁷ erg/s. Equivalently, 1 erg/s = 10⁻⁷ W = 0.1 μW.
In astrophysics, the erg/s is still commonly used for expressing luminosity. The Sun's luminosity is approximately 3.828 × 10³³ erg/s (3.828 × 10²⁶ W). Stellar and galactic luminosities spanning many orders of magnitude are often more conveniently expressed in CGS units, which is why astrophysics has been slow to adopt SI.
Our converter provides results in watts, milliwatts, and kilowatts. Since erg/s values are typically very large numbers (representing significant power levels), the watt output is usually the most practical. For small power levels, milliwatt output is provided for convenience.
The formula: watts = erg/s × 10⁻⁷. This is exact, based on the CGS-to-SI unit definitions. For milliwatts: mW = erg/s × 10⁻⁴. For kilowatts: kW = erg/s × 10⁻¹⁰.
Scale reference: 1 W = 10⁷ erg/s. Solar luminosity = 3.828 × 10³³ erg/s. A 100 W light bulb = 10⁹ erg/s. A milliwatt laser = 10⁴ erg/s. Cellular metabolic processes operate at ~10⁻² to 10² erg/s.
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10⁷ erg/s = 1 W exactly
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Fraction of solar luminosity
1 erg/s = 10⁻⁷ watts = 0.1 microwatts. This is an exact conversion based on CGS-to-SI unit definitions.
The erg is the CGS unit of energy, equal to 1 g·cm²/s² = 10⁻⁷ joules. It is named from the Greek word 'ergon' meaning work.
Astrophysics adopted CGS units early and has extensive legacy literature in these units. CGS electromagnetic equations are also simpler (no factors of 4πε₀). The transition to SI is gradual.
The solar luminosity is L☉ = 3.828 × 10³³ erg/s (3.828 × 10²⁶ W). This is a standard reference value defined by the IAU.
Multiply watts by 10⁷. For example, 5 W = 5 × 10⁷ erg/s.
The centimeter-gram-second system uses cm, g, and s as base units (vs SI's m, kg, s). CGS energy = erg, CGS force = dyne, CGS power = erg/s.
Not in SI standards, but the erg remains in active use in astrophysics journals and some geophysics publications. The IAU has recommended SI but accepts CGS.
1 kW = 10¹⁰ erg/s (10 billion ergs per second).
1 joule = 10⁷ ergs exactly. The joule uses kg and m (SI), while the erg uses g and cm (CGS). They measure the same physical quantity.
Multiply by 10⁻³. The factor accounts for both the erg→J conversion (10⁻⁷) and the cm²→m² conversion (10⁴), giving 10⁻³ overall.
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