The Size of Everything

As the title says, this is a chart of the size range of everything known, microscopic and macroscopic, on a logarithmic scale. The opaque range for each category indicates the size range of objects that have actually been measured, while the gradient indicates either uncertainty, what may yet be found or what is theoretically possible. Large uncertainties are annotated in the table below, as well as values that I found surprising. The data are mostly from Wikipedia, corroborated with the links given in the annotations. Additionally, a conversion table for all used length units is given.

There are much more elaborate implementations of this kind of scale from smallest to largest on the web, but I wanted it all in one comprehensive view so that comparisons can be made at a glance, and, well this is the result:

[Click to enlarge]

See also The Mass of Everything.

Object typeSize range
Size range
[Common unit]1
Particle 1.0×10-24 – 1.0×10-18 1 zm – 1 am
Good overview over particle sizes here, especially the particle chart.
Nucleus 1.7×10-15 – 1.5×10-14 1.6 fm – 15 fm
Simple formula to calculate the radii of atomic nuclei by mass number.
Atom 5.0×10-11 – 6.7×10-10 50 pm – 670 pm
Atomic sizes overview
Molecule 1.4×10-10 – 5.0×10-9 140 pm – 5 nm
This refers only to molecules found in space so far. The largest known molecules, i.e. DNA, measure in millimeters, so there is much room for growth yet.
Cell 1.5×10-8 – 1.2×101 15 (200) nm – 12 m
Cell sizes from here. The smallest cell size depends on if Viruses count as cells. The largest, according to this, is a 12m long Octopus nerve cell.
Dust 1.0×10-7 – 1.0×10-4 0.1 μm – 0.1 mm
According to Larry Nittler, "Presolar Grains in Meteorites", the smallest grain size found is 2nm, but I don't know if this means those grains are meant to be once free dust particles, so I left it approximate.
Meteoroid 1.0×10-4 – 1.0×101 0.1 mm – 10 m
There seems to be a defined Dust/Meteoroid cutoff at 0.1mm in all of the literature I searched (see e.g. here).This is because 0.1mm is the minimum size for an object to become visible as a meteor upon entering Earth's atmosphere.
Meteoroids (and Micrometeoroids) are defined as debris from Asteroids or Comets "considerably smaller than a asteroid" (see IMO Glossary). Micrometeoroids in this definition represent the lower range from 0.1-~1mm. For the upper limit see below.
Asteroid 1.9×102 – 9.5×105 190 m – 1000 km
I assumed a dividing line size limit of ~10m, as discussed here. As I interpret it, this would mean that comets also range down to that limit.
TNO 1.0×103 – 2.6×106 1 – 2600 km
The smallest observed Trans Neptunian Object is ~1 km, but there is no reason to assume that TNOs don't have the same size range as Asteroids/Meteoroids. TNOs include the Kuiper belt, the Scattered disk, the Detached objects and the Oort Cloud. The discovered objects are mostly from the former three groups, with a few possible exceptions. (See Mike Brown's homepage below).
Comet 5.0×102 – 1.0×105 500 m – 100 km
(See 'Asteroid')
Moon 5.0×102 – 5.3×106 500 m – 5300 km
This is the range of all moons discovered so far. The lower limit is again a matter of definition; specifically if ring material orbiting a planet were also considered moons, the range would go down all the way to dust. ('Dwarf moons', maybe?)
Dwarf Planet 4.0×105 – 2.6×106 950 – 2600 km
The current smallest Dwarf Planet is Ceres at 950km, but according to Mike Brown, "The dwarf planets", TNOs down to ~400km would qualify under the current rules.
Planet 4.9×106 – 2.0×108 0.38 – 15.4 D
Brown Dwarf 1.5×108 – 2.5×108 0.11 – 0.18 D
Giant Planets, Brown Dwarfs and the least massive Red Dwarfs are all about the same size, but of increasing mass, since their density increases with mass. Brown Dwarfs (Wikipedia); Comparison Chart.
Main Sequence Star 1.8×108 – 2.5×1010 0.13 – 17.8 D
Star 3.0×103 – 3.0×1012 3 km – 2150 D
The category 'Star' here contains everything from Neutron Stars to Red Giants, while the category above includes only regular stars of the main sequence. The big ones. (Wikipedia)
Black Hole 1.8×104 – 3.8×1013 18 km – 300 AU
Black Hole size here stands for it's Schwarzschild diameter. A good overview: Karl Gebhardt's "Black Hole Encyclopedia" (The lower range uncertainty comes from hypothetical primordial black holes at ~0.5 Msolar.)
Protoplanetary Disk 1.5×1013 – 3.0×1014 100 – 2000 AU
Since Protoplanetary disks and Dark Nebulae contain more or less the same kind of material (i.e. Dust and Molecules), it isn't quite clear where one starts and the other ends. There may be a continuous transition from Dark Cloud > Bok Globule > Protostellar Disk > Protoplanetary Disk (see Secrets of a Dark Cloud, ESO 1999)
Planetary Nebula 1.1×1015 – 7.9×1016 0.1 – 8 ly
Supernova Remnant 1.0×1017 – 1.7×1019 10 – 1800 ly
Supernova Remnants and Planetary Nebulae start off at the size of the originating star and disperse until they are indistinguishable from the interstellar Medium, so the theoretical size range is much larger than the observed one.
Emission Nebula 9.3×1014 – 1.5×1019 0.1 – 1600 ly
For the minimum size, see Stan Kurtz, "Hypercompact HII regions"
The maximum size depends on if Hanny's Voorwerp at ~100 kly counts as an emission nebula, raising the limit by orders of magnitude in comparisons to galactic EN's at max. 1.5 kly.
Bok Globule 4.7×1015 – 1.9×1016 0.5 – 2 ly
(See 'Protoplanetary Disk')
Dark Nebula 1.9×1016 – 4.7×1019 2 ly – 50 kly
(See also 'Protoplanetary Disk') From visual evidence I assumed that Dark Clouds can span the entire disk of their host galaxy (e.g. M104, NGC 5128, NGC 7049, NGC 4526). Also, since Reflection Nebulae are basically a part of a Dark Cloud that is illuminated by a nearby star, and their bounds are not very well defined, they don't get an extra entry.
Open Cluster 1.3×1016 – 1.4×1018 1.4 – 330 ly
Open cluster stars tend to drift further apart with time, becoming "moving clusters" and loose associations, so the upper limit isn't precisely definable.
Globular Cluster 3.3×1016 – 3.5×1018 3 – 350 ly
(see 'Galaxy')
Galaxy 6.2×1018 – 5.3×1022 0.6 – 4,000 kly
For the lower limit of galaxy sizes see Steffen Mieske, "Ultra compact dwarf galaxies." Where the cutoff between Globular Clusters and UCDs is or even if there is a continuous transition between them is still a research problem.
The largest galaxy known so far is IC 1101.
Galaxy Group 9.5×1020 – 6.1×1022 100 kly – 6.5 Mly
Galaxy Cluster 5.6×1022 – 2.8×1023 6 – 30 Mly
Supercluster 2.8×1023 – 3.3×1024 30 – 350 Mly
See here for size ranges of galaxy groups, clusters and superclusters. The are the size ranges with the largest uncertainties yet, as they depend on many parameters both observational and physical, e.g. the value of the Hubble constant, Dark matter and what kind of Universe we live in anyway.
Filament 3.3×1024 – 1.3×1025 350 Mly – 1.3 Gly
Filaments or walls as defined here are the largest identifiable parts of the known large scale structure of the universe and include objects like the Sloan Great Wall.
The Universe >9.3×1026 >93 Gly
46.4 Gly would be the current distance of the furthest structures we can see as they were ~13 billion years ago. Thus the minimum diameter of the universe right now is ~93 Gly. See: Davis, T.M., Lineweaver C.H., "Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the universe."

The reference points:

Planck length2 1.6 x 10-35 m = √ℏG/c3
Particle sizes νe:~10-24 m
e-: ~10-18 m
p: ~10-15 m
Water Molecule 2.75 x 10-10 m
Needle point ~1 µm
Stone Louse3 0.3-3 mm avg. 1 mm
Human 1-2.5 m avg. ~1.7 m
Earth D 1.27 x 104 km
Sun D 1.39 x 106 km
Solar system 1 x 105 AU = 1.5 x 1016 m
Milky Way 100 kly = 9.5 x 1020 m
Visible universe 13.7 Mly = 1.3 x 1026 m
with ℏ = Planck's constant (hbar) (1.054,571,628 × 10-34 Js)
G = Gravitational constant (6.674,28 × 10-11 m3/kgs2
c = Light speed in vacuum (299,792.458 km/s)

1) Common unit: Unit most commonly found for each kind of object.
2) See John Baez' page for details about Planck length and particle sizes.
3) This critter.

Wikipedia overviews: Astronomical object, Solar System Portal, Solar System objects by size ,
List of largest known stars
Particles, Plank length: John Baez
Constants: Chris Dolan
Dust: Presolar Grains in Meteorites
Small Bodies: Glossary of the International Meteor Association; Beech, M. et al., On the Definition of the Term Meteoroid
Planets & Moons: NASA planetary fact sheets; The Extrasolar Planets Encyclopaedia; Mike Brown, The dwarf planets
Stars: Star sizes, Our Stellar Neighborhood (Harry’s 'Comparative Astronomy' Pages)
Black Holes: Karl Gebhardt's "Black Hole Encyclopedia"
Nebulae: Kurtz, S., Hypercompact HII regions Secrets of a Dark Cloud (ESO press release 29/99)
Star Clusters, Galaxies: Hilker, M., The high mass end of extragalactic globular clusters
Steffen Mieske, Ultra compact dwarf galaxies
Bill Keel, Galaxies and the Universe
Galaxy Groupings: Compact Groups of Galaxies (Paul Hickson); Galaxy Groups and Clusters, Galaxy Filaments (Wikipedia); Large Scale Structure, T. Jarrett