====== Model Railway Scales ======


^ Scale ^ Ratio ^ Gauge ^ Notes ^
| N | 1:152 | 9.42mm 0.321" | There is a track gauge error of approximately -7% |
| OO 4mm | 1:76 | 16.5mm 0.65" | The correct track gauge at the scale of 4 mm per foot should be approximately 18.8 mm. At 16.5 mm, it has a track gauge error of approximately -12.4% |
| P4 S4 | 1:76.2 | 18.83mm 0.741" | The track gauge of 18.83 mm represents an exact scaling down of the prototype at 4 mm to 1 ft scale. P4 contains an allowance for the tighter curves found on model railways in the wheel back-to-back and related dimensions. S4 removes this allowance, for a dead-scale representation of all trackwork dimensions. |
| O 7mm | 1:43.5 | 32mm 1.26" | There is track gauge error of approximately -3% |
| Standard | 1:1 | 1435mm 56.5" | 4'8½" |

=== To convert ===
| OO -> O | x 1.747 |
| O -> OO | ÷ 1.747 |
| Standard -> OO | ÷ 76 |
| Standard -> O | ÷ 43.5 |