Track Gauge Calculator

The World's Railways Don't Share a Common Width

Track gauge — the distance between the inner faces of the two rails — determines whether rolling stock built for one railway can physically run on another. Most of the world settled on a single figure generations ago, but enough networks didn't that gauge remains a real constraint on cross-border and cross-network operation. This calculator converts a gauge measurement to inches and classifies it against the standard.

The Formula

Standard gauge is defined as exactly 1435 mm (4 ft 8.5 in). Anything narrower is classified as narrow gauge; anything wider is broad gauge.

Where This Is Useful

• Interoperability checks — before rolling stock, bogies, or track components can be shared between two networks, their gauges have to match.
• Historical and regional research — many countries and regions adopted a specific gauge for reasons tied to terrain, cost, or colonial-era infrastructure decisions, and that choice still shapes their network today.
• Heritage and narrow-gauge railways — tourist and industrial lines frequently use a narrower gauge than the national mainline network, and confirming the exact figure matters for sourcing compatible parts.

Common Track Gauges

Standard gauge (1435 mm) is the most widely used gauge globally, but narrow and broad gauge networks remain extensive in regions including parts of Africa, South America, the Indian subcontinent, and the former Soviet Union.

How to Use This Calculator

1. Enter the Track Gauge in millimeters.
2. Select Calculate to get the equivalent in inches and a classification as Narrow, Standard, or Broad Gauge.

Related Calculations

Once gauge is confirmed, check Curve Radius for another core track geometry figure, or Axle Load to check whether rolling stock is within the track's weight limits.