Make the distance familiar
A 500 km length contains 5,000 straight 100 m sections. Picture a marked 100 m sprint straight repeated end to end, rather than a whole stadium lap.
Work it out, one step at a time
Turn kilometres into metres
500 × 1,000 = 500,000 m
One kilometre contains 1,000 metres. The length stays the same.
Choose a speed, then find the time
500 km ÷ 100 km/h = 5 h
At a chosen constant 100 km/h, it takes about 5 hours. This is a calculation with no stops; hills, traffic and real journey conditions are not included.
What if the speed doubles?
For the same distance and constant speed, time halves. For example, 10 km takes 2 hours at 5 km/h but 1 hour at 10 km/h.
The distance is this page’s chosen input. The speed is a teaching assumption. Time = distance ÷ speed.
Build a scale modelChoose two references and change the model size.
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 · South Korea
500 km
Stated linear extent of the named reference.
Existing journey comparison assumption; numeric evidence review pending.
The existing visualizer retains this educational comparison. Its numerical value is withheld from this distribution until its precise definition and primary evidence are checked.
Definition and evidence reviewOriginal sourceB · Marathon
42.195 km
Official marathon race distance, 42.195 km.
Source claim checked
A standardized course length; course certification and an athlete’s path require separate measurement.
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.
Following Earth's surface versus joining the endpoints
Treat Earth as a sphere with the 6,371 km mean radius. A 500 km shortest surface arc subtends θ = s/R = 0.07848 radians, or about 4.497°. Its chord joins the same endpoints through the sphere's interior. Predict which length is greater.
Chord length = 2R sin(θ/2) = 499.872 km. Compared with the 500 km arc, the difference is about 128.3 m. Both figures are model-derived lengths: they compare curvature with a straight interior segment, rather than measuring a particular road or tunnel.
Keep the Earth model and the route definition together
The arc follows a spherical surface; the chord passes below it. Earth's flattening, elevation and real transport routes call for more detailed models. Start a regional comparison by stating whether “500 km” means road distance, a surface geodesic or a straight line. Earth's radius definitions explain why a more precise map uses more than one rounded radius.
Closest ScaleTrip references
Page distance: 500 km
- South KoreaReference measurement: Length · 500 km
Ratio (page distance ÷ reference): ≈ 1×A representative north-to-south extent of South Korea.
- Los Angeles–San FranciscoReference measurement: Distance · 560 km
Ratio (page distance ÷ reference): ≈ 0.89×The distance between Los Angeles and San Francisco.
- Tokyo–OsakaReference measurement: Distance · 400 km
Ratio (page distance ÷ reference): ≈ 1.25×The distance along Honshu between Tokyo and Osaka.
Sources for these values
- NASA NSSDC — Earth Fact Sheet — 6,371 km volumetric mean radius used in the spherical arc/chord calculation · calculation verified from source value 2026-10-13