Terrain & large worlds
Open-World Travel-Time & Map-Size Calculator
Direct answer
Open-world size is better expressed as traversal time than square kilometres. An 8x8 km map has an 11.31 km straight diagonal; at 20 km/h with a 1.25 route-detour factor, crossing it takes about 42.4 minutes. POI count then reveals whether that travel contains meaningful beats or empty distance.
1.0 is a straight line; 1.25 means roads or terrain add 25% distance.
Result
- Effective diagonal crossing time
- —min
- Map area
- —km2
- Straight diagonal
- —km
- Effective diagonal route
- —km
- Width crossing time
- —min
- Average area per POI
- —km2
- Square-grid POI spacing
- —km
- Speed needed for target time
- —km/h
Method & assumptions
How this is worked out
Area is width multiplied by length. Straight diagonal uses Pythagoras, then multiplies by the route-detour factor to represent roads, switchbacks, obstacles and non-linear terrain.
Travel time is effective distance divided by sustained speed. It excludes combat, menus, stamina, loading, stops and acceleration, so measured playtest journeys will normally take longer.
Average POI spacing treats content as an even square grid: sqrt(map area / POI count). Real worlds should vary rhythm deliberately, but the number exposes whether the macro density matches the intended travel cadence.
Use sustained speed, not animation peak
| Travel mode | Planning speed | Common interruptions |
|---|---|---|
| Walking | 4–6 km/h | Slopes, doors, dialogue |
| Running | 10–18 km/h | Stamina, combat, climbing |
| Horse / mount | 20–40 km/h | Terrain and road bends |
| Road vehicle | 40–100 km/h | Junctions, traffic, obstacles |
| Fast flight | 100+ km/h | Streaming and world visibility |
These are broad planning ranges, not genre rules. Measure the sustained speed of the actual controller over representative terrain.
Questions
Why use a route-detour factor?
Players rarely cross a world in a perfect straight line. Terrain, streets, rivers, entrances and encounter routing add distance. The factor converts geometric distance into a more believable route estimate.
How many POIs should an open world have?
There is no universal count. Start from the desired time between meaningful beats, sustained travel speed and usable area. The spacing output lets you compare that intention with the current content count.
Does map area predict how large a game feels?
Poorly. Speed, visibility, path shape, verticality, encounter density and fast travel matter more. Two maps with identical square kilometres can feel completely different when traversal and content rhythm differ.