When HO is 1:87 scale and when it’s 1:64 scale

Last Updated on October 22, 2022 by Dave Farquhar

I get a lot of questions about the difference between HO scale and 1:64, and it occurred to me that I missed something. I was thinking of model train HO scale, which is 1:87, which is about 25% smaller than 1:64. But for whatever reason, slot car HO scale is 1:64. So here’s how to know when HO is 1:87 scale and when it’s 1:64 scale.

When HO scale is 1:64 scale

Slot car HO scale is 1:64 scale, not the same as for trains. Image credit: Joe Haupt,

So, if you’re wondering whether 1:64 scale die-cast vehicles are appropriate for your hobby, it depends. If you’re outfitting an HO scale slot car layout, 1:64 diecasts such as those marketed by Johnny Lightning and M2 are perfect, and so is anything S scale from the model train world. Hot Wheels and Matchbox cars will often be undersized, but check the width. If it’s slightly wider than the distance between the top knuckle and the tip of your thumb, the scale is close enough to 1:64 that you probably won’t notice the difference. Here are some other tips for estimating 1:64 scale.

Yes, keep in mind when you’re borrowing from model trains, the correct match for HO scale slot cars is S scale model railroading.

When HO scale is 1:87 scale

When outfitting an HO scale model railroad layout, 1:64 diecasts are oversized. In model railroads, 1:64 is S scale. The popular HO scale is 1:87 scale. But keep in mind that while we think of Hot Wheels and Matchbox as 1:64, they’re often smaller than that. Whether you want to use them is up to you. I’ve written about estimating HO scale-sized cars before. Basically, if it’s about as wide as a nickel, it’s close to HO scale.

Here’s an explanation of model train scales and sizes, if it helps.

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