The National Model Railroad Association (NMRA) has Standards and Recommended Practices for various things for Model Railroads. These range from track spacing, wheel profiles, module specifications, and Car Weight. I’m going to focus on Car Weight for a little bit.
RP-20.1 Car Weight sets up a recommended practice for what the model cars should weigh. It rather straight forward, start with 5 ounces and add 1 ounce per inch of car length.
I’m going to add different models and their weights to this Chart. I will reference it when I review the different cars for the layout. The heaviest cars are on top.
Numbers in Blue type are under are under the NMRA Standards.
Numbers in Red type are OVER NMRA Standards.
Last Updated: 03/30/25
| Manufacturer | Model | Car Length | RP Weight | Actual Weight | Over / Under |
| Lionel | Three Bay Hopper (H43) | 12 in. | 17 oz. | 40 oz | +23 oz. |
| Atlas O | Fishbelly | 8 in. | 13 oz | 29 oz | +16 oz. |
| Atlas O | War Emergency Hopper | 8.25 in. | 13.25 oz | 26 oz | +12.75 oz. |
| Lionel | 50 Ton Offset Hopper | 8.5 in. | 13.5 oz | 26 oz | +12.5 oz. |
| Protocraft | SP 50 ft Boxcar | 12.5 in. | 17.5 oz | 28 oz. | +10.5 oz |
| RY Models | ACL Venttilated Box Car | 9.5 in | 14.5 oz | 23.2 oz | +8.7 oz |
| All Nation | 50 Ton Offset Hopper | 8.5 in. | 13.5 oz | 21 oz | +7.5 oz. |
| Overland | PRR H32 Covered Hopper | 13 in. | 18 oz | 22 oz | +4 oz. |
| Atlas | PRR H21a Hopper | 10 in. | 15 oz | 18 oz | +3 oz. |
| Kohs | PRR GLe Hopper | 8 in. | 13 oz | 16 oz | +3 oz |
| Tangent Scale Models | GATC 6,000 Gallon 3-Compartment tank car | 8 in. | 13 oz | 14 oz | +1 oz |
| Lionel | PRR GLa Hopper | 8 in. | 13 oz. | 12.5 oz | -0.5 oz. |
| MTH | Fishbelly Hopper | 8 in. | 13 oz | 12 oz | -1 oz. |
| PSC | PRR GLa Hopper | 7.75 in. | 12.75 oz | 11 oz | -1.75 oz. |
| PSC | PRR H31 Hopper | 8 in. | 13 oz | 11 oz | -2 oz. |
| USH | PRR H25 Hopper | 10 in. | 15 oz | 13 oz | -2 oz. |
| Yoder Models | PRR GLCa Hopper | 8 in. | 13 oz | 11 oz | -2 oz. |
| Yoder Models | PRR H21a Hopper | 10 in. | 15 oz | 13 oz | -2 oz. |
| Yoder Models | 50 ton Offset Hopper | 8.5 in. | 13.5 oz | 11 oz | -2.5 oz. |
| Atlas O | USRA Twin Hopper | 7.75 in. | 12.75 oz | 10 oz | -2.75oz. |
| Yoder Models | PRR GLa Hopper | 7.75 in. | 12.75 oz | 10 oz | -2.75 oz. |
| Atlas | USRA Pannel Sides Hopper | 8 in. | 13 oz | 10 oz | -3 oz. |
| Weaver | B&O M-53 Box Car | 10 in. | 15 oz | 12 oz | -3 oz. |
| MTH | 50 ton Offset Hopper | 8.5 in. | 13.5 oz | 10 oz | -3.5 oz. |
| MTH | War Emergency Hopper | 8.5 in. | 13.5 oz | 10 oz | -3.5 oz. |
| Atlas | TM 70 Ton 9 Hopper | 10.75 in. | 15.75 oz | 12 oz | -3.75 oz. |
| Intermountain * | USRA Twin Hopper | 7.75 in. | 12.75 oz | 8.5 oz | -4.25 oz. |
| Intermountain Kitbash * | RDG HTn Quad Hopper | 10.75 in. | 15.75 oz | 10.5 oz | -5.25 oz. |
| Nice Fish Model Company | CN 70 Ton Flat Car | 13 in | 18 oz | 9.7 oz | -8.3 oz |
* Kiel Line Weights added