Cubes beat circles
If a planet is just twice Earth’s diameter, it’s 8× Earth’s volume. That cube rule is why gas giants win any “how many fit” contest instantly.
Volume magic
How Many Earths Fit in the Sun? Calculator and Formula
Short answer
About 1.3 million Earths fit inside the Sun by volume.
- Standard astronomy answer: 1,302,096 Earth-sized volumes fit in a Sun-sized volume, using mean radii.
- Across the Sun's diameter: about 109 Earths fit side by side.
- If Earth-sized solid spheres had to leave gaps: about 964,000 Earths fit using a 74.048% sphere-packing estimate.
Reviewed by Starlight Tools editors on June 29, 2026. Method: mean radii, spherical volume, and an optional densest sphere-packing constant.
Result
About 1,300,000 Earths fit inside the Sun by volume.
Standard astronomy answer: volume comparison
- Earths
If Earth-sized solid spheres had to leave gaps
- Earths
Diameter comparison
About 109 Earths fit across the Sun's diameter.
Radius ratio
Sun radius / Earth radius = about 109.2.
- Count = (big radius / small radius)^3
- Count = (695,700 / 6,371)^3
- Count = about 1,302,096 Earths by volume
Assumes perfect spheres and mean radii.
Scale diagram: Sun diameter, Earth diameter, 109 Earths across, and why volume uses the cube of the radius ratio.
Calculator controls
The standard astronomy answer compares volume. Packing applies only if solid spheres must leave gaps.
Tip: choose a preset above for the most common comparisons.
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Formula: why the answer is about 1.3 million
Use R for the Sun's radius and r for Earth's radius. A sphere's volume is V = 4/3 x pi x radius^3, so the shared 4/3 x pi part cancels out when we compare two spheres.
Count = (R / r)3
For the default Sun/Earth comparison: R = 695,700 km and r = 6,371.0 km. The radius ratio is 695,700 / 6,371.0 = 109.1979. Cube that ratio: 109.19793 = 1,302,096.6. Rounded for a plain answer, about 1.3 million Earths fit inside the Sun by volume.
The packed-sphere estimate is separate: 1,302,096.6 x 0.74048 = 964,176.5. That lower number answers a different question: how many Earth-sized solid spheres might fit if gaps between spheres count against the total.
Common space size comparisons
| Question | Standard answer | Packed-sphere estimate | Notes |
|---|---|---|---|
| Earths in the Sun | 1,302,096 Earths by volume (about 1.3 million) | 964,176 Earth-sized spheres | Sun radius 695,700 km; Earth radius 6,371.0 km. |
| Earths across the Sun's diameter | About 109 Earths across | Not applicable | This is a width comparison, not a volume comparison. |
| Earth masses in the Sun | About 333,000 Earth masses | Not applicable | Mass is different from volume; the Sun is mostly hydrogen and helium plasma. |
| Jupiters in the Sun by volume | 985 Jupiters | 729 Jupiter-sized spheres | Uses Jupiter mean radius 69,911 km. |
| Earths in Jupiter | 1,321 Earths | 978 Earth-sized spheres | NASA's simple public wording often rounds this to about 1,000 Earths. |
| Moons in Earth | 49 Moons | 36 Moon-sized spheres | Uses Moon mean radius 1,737.4 km. |
| Moons in Jupiter | 65,153 Moons | 48,244 Moon-sized spheres | A volume comparison only; it does not describe orbital space around Jupiter. |
Data used
Sun radius
695,700 km. NASA gives the Sun's radius as about 700,000 km and says about 1.3 million Earths fill the Sun's volume; the calculator uses the IAU nominal solar radius for consistent math.
Earth radius
6,371.0 km mean radius. The visible Earth section also notes Earth's 12,756 km equatorial diameter.
Radius ratio
695,700 / 6,371.0 = 109.1979, so about 109 Earths fit across the Sun's diameter.
Volume ratio
109.19793 = 1,302,096.6, so the plain-language answer is about 1.3 million Earths.
Packing constant
0.74048, the densest equal-sphere packing fraction. Multiplying the volume answer by this gives about 964,000 Earth-sized spheres.
Methodology and review
Author/editor: Starlight Tools educational content team. Last reviewed: June 29, 2026.
Results use mean or nominal radii and model each object as a sphere. The default result is a volume comparison, which is the standard astronomy answer. The packed estimate is shown separately because equal spheres leave empty gaps even in the densest arrangement.
FAQ
Is it 1 million or 1.3 million Earths?
The standard astronomy answer is about 1.3 million Earths by volume. With the calculator's values, (695,700 / 6,371.0)3 = 1,302,096.6.
Why do some sites say 1 million?
Some explanations round heavily for younger readers, use rounded diameter values, or switch from volume comparison to a packing idea. The volume answer is about 1.3 million; the packed-sphere answer is about 960,000.
How many Earths fit across the Sun?
About 109 Earths fit across the Sun's diameter. Diameter and radius use the same ratio, so this is 695,700 / 6,371.0 = 109.1979.
How many Earths equal the Sun's mass?
About 333,000 Earth masses equal the Sun's mass. This is not the same as volume because Earth and the Sun have very different densities and materials.
Could Earth really survive inside the Sun?
No. This calculator is a geometry comparison. A real Earth would be destroyed by the Sun's heat, plasma, radiation, gravity, and pressure.
Does the Sun have a solid surface?
No. NASA describes the visible layer as the photosphere, but the Sun does not have a solid surface. It is a hot ball of plasma.
What radius values does this calculator use?
The default answer uses a Sun radius of 695,700 km and an Earth mean radius of 6,371.0 km. Other presets use the radii listed in the calculator's body menu.
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