Nearest reference
Characteristic lengthOne metre
1 m
The starting frame: a familiar unit before the camera moves inward.
Into the small · 10⁰ → 10⁻²⁰ m
Small worlds. Big discoveries.
From cells and DNA to atoms and particle searches. Move through the scale to explore worlds too small to see.
Each step from millimetre to micrometre to nanometre divides by 1,000
Look at a 1 mm gap on a ruler. Split that gap into 1,000 equal parts: each part is 1 µm. Split one of those parts into 1,000 again: each is 1 nm.
Work it out, one step at a time
Choose the smaller unit
1 µm = 1,000 nm
Just as 1 m = 100 cm, using a smaller unit gives a larger number.
Apply the rule to a specimen
7.5 µm = 7,500 nm
Do not divide 7.5 directly by a width written as 2 nm. Match the units first.
Words made simple
- µm
- Micrometre: one millionth of a metre.
- nm
- Nanometre: one billionth of a metre.
Think about it: Which is longer: 2 µm or 500 nm?
2 µm is 2,000 nm, which is four times 500 nm. A larger written number alone does not mean a longer object.
Where the numbers come from: NIST · NHGRI. The illustration and worked model are made for this lesson; assumptions are stated above.
Conceptual visualization
Jump to a small length
Enter a number and unit to locate its nearest reference on the same logarithmic timeline.
Build a scale model of any two lengths
Choose from all 71 Macro and 54 Micro references, or enter your own length. Set B’s model length and see A change on the same fixed metre ruler. The bars represent the stated lengths, including their different measurement definitions.
- Length ratio A / B
- Model length B
- Calculated model length A
A · Human hair
80 µm
Chosen 80 µm cross-section diameter for comparison; not a study or population mean.
Chosen comparison assumption
Tables 4–5 distinguish major/minor axes. The 50–100 µm display band is illustrative; strands can lie outside it.
Definition and evidence reviewOriginal sourceB · Red blood cell
7.5 µm
Chosen 7.5 µm representative diameter; the cited study reports a 7.65 µm sample mean.
Chosen comparison assumption
Publisher abstract reviewed, not full text. Study SEM 0.05 µm differs from SD 0.67 µm. Display band 6–8 µm is illustrative.
Definition and evidence reviewOriginal sourcemodel A = (A / B) × model B
This calculator uses the existing journey comparison inputs. Review-pending or conceptual entries remain illustrative inputs here; the public reviewed dataset keeps their numeric values withheld. Radius, height, diameter and experimental bound keep their individual definitions.
The journey at a glance
From cells to the experimental frontier
This image conceptually connects several orders of magnitude in one frame. Use the interactive journey and individual scale pages for the measured values and measurement types.
Reading a continuous scale
Not every small length means the same thing
Cells and viruses can be compared by typical diameter; DNA and atoms are described through molecular structure and electron-distribution characteristic lengths. A crystal lattice value is a spacing, while the strong force is described by an interaction range. ScaleTrip therefore separates physical size, typical diameter, spacing, characteristic length and interaction scale.
Length upper bounds from collision experiments
Below the proton scale, quark values are upper bounds on substructure lengths constrained by collision searches. Current results are consistent with pointlike models down to those limits. The artwork is a conceptual detector or interaction diagram.
- Human cell
- 10–100 µm
- DNA
- ≈ 2 nm
- Typical atom
- ≈ 0.1–0.3 nm
- Proton charge radius
- 0.84075 fm
- Experimental frontier
- ≈ 10⁻²⁰ m
Method and sources
Ranges stay visible, and source status is explicit
The 54 references run from one metre to 10⁻²⁰ metres in descending order. Camera position is interpolated logarithmically, while scenes cross-zoom using CSS transforms and opacity only. Where a value depends on species, conditions or definition, the interface shows a range and approximation.
- NCBI Bookshelf — representative cell, bacterium and virus scales
- National Human Genome Research Institute — DNA double-helix diameter
- NIST 2022 CODATA — Bohr radius, proton charge radius and Planck length
- CERN CMS — length scale of searches for quark substructure
Theoretical epilogue: the Planck length
1.616255 × 10⁻³⁵ m — This theoretical scale is assembled from fundamental constants. It lies beyond current experimental reach and is explored separately from the main timeline.