Nominal Solar Luminosity
| Value | 1 Lsun (3.828 × 10²⁶ W) |
| Status | Exact by definition: no uncertainty |
| Source | IAU 2015 Resolution B3 |
| Categories | AstronomicalStars & Sun |
| Unit | Value |
|---|---|
| solar luminosity | 1 Lsun |
20 more power units
| nanowatt | 3.8280000e+35 nW |
| erg per second | 3.8280000e+33 erg/s |
| microwatt | 3.8280000e+32 μW |
| milliwatt | 3.8280000e+29 mW |
| foot pound-force per minute | 1.6940327e+28 ft·lbf/min |
| BTU per hour | 1.3061678e+27 BTU/h |
| watt | 3.8280000e+26 W |
| kilocalorie per hour | 3.2914875e+26 kcal/h |
| foot pound-force per second | 2.8233879e+26 ft·lbf/s |
| thousand BTU per hour | 1.3061678e+24 MBH |
| metric horsepower | 5.2046316e+23 PS |
| horsepower (mechanical) | 5.1334326e+23 hp |
| electrical horsepower | 5.1313673e+23 hp (elec) |
| kilowatt | 3.8280000e+23 kW |
| ton of refrigeration | 1.0884732e+23 ton |
| boiler horsepower | 3.9023396e+22 bhp |
| million BTU per hour | 1.3061678e+21 MMBTU/h |
| megawatt | 3.8280000e+20 MW |
| gigawatt | 3.8280000e+17 GW |
| terawatt | 382,800,000,000,000 TW |
Learning zone
The Sun's total radiant power follows from one measurement and one sphere: take the total solar irradiance at Earth's distance, about 1361 W/m², and multiply by the area of a sphere of radius one au. The nominal value fixed by the IAU in 2015 is exactly 3.828 × 10²⁶ W, deliberately rounded so that it does not change when irradiance monitoring improves, and so that "L = 10⁵ L⊙" means the same thing in every paper.
The real Sun varies by about 0.1 per cent over the 11-year sunspot cycle: enough to matter for climate reconstructions, nowhere near enough to matter for stellar classification. For scale, that output is roughly 10¹⁴ times humanity's entire primary energy consumption, and it comes from converting about 4.3 million tonnes of mass into energy every second in the core.
Cite this page
formula.expert. (2026, October 16). Nominal Solar Luminosity. https://formula.expert/constants/nominal-solar-luminosity