THE NUMBERS, EXPLAINED
How to use this calculator.
Bodies exclude coupling gaps. A locomotive plus the listed cars creates one gap per car. This checks straight-platform length only.
Start with your inputs
Enter car body lengths (mm), locomotive body length (mm), inter-vehicle coupling gap (mm), usable platform length (mm). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Car body lengths (mm) | 200,220,200 |
| Locomotive body length (mm) | 180 |
| Inter-vehicle coupling gap (mm) | 10 |
| Usable platform length (mm) | 850 |
A worked example
With the example inputs above, complete train length (mm) is 830. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Complete train length (mm) | 830 |
| Platform spare length (mm) | 20 |
| Fits platform | Yes |
How this is calculated
Complete train length (mm)
Add all bodies plus the gaps between adjacent vehicles.
Platform spare length (mm)
Subtract train length from platform length.
Fits platform
Compare complete train length with usable platform.
Symbols and units
- a
- Car body lengths (mm)
- b
- Locomotive body length (mm)
- c
- Inter-vehicle coupling gap (mm)
- d
- Usable platform length (mm)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
Bodies exclude coupling gaps. A locomotive plus the listed cars creates one gap per car. This checks straight-platform length only.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Complete train length (mm); Platform spare length (mm); Fits platform. The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Bodies exclude coupling gaps. A locomotive plus the listed cars creates one gap per car. This checks straight-platform length only.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Further reading
OpenStax: Solve proportions and their applications ↗
Background reading; this does not imply endorsement or independent review of SumFizz.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
Read the quality report →