Once every couple of weeks, I see someone ask about using 1:72 scaled miniatures along with their 28mm miniatures.
This isn’t a dumb question: I’ve certainly asked it myself! There’s a plethora of inexpensive 1:72 stuff out there, and 28mm is kind of a weird, messy scale that doesn’t have a convenient 1:something ratio and is often accompanied by freakish, unusual proportions.
1:72 is a fine scale (I find it unsatisfying from a hobby perspective, but I’ve been convinced that from a gaming perspective it’s the greatest of scales), but it is wildly out of whack with 28mm miniatures.
As you can see: the 1:72 scale miniature is about half as tall as a 28mm scaled miniature. The two scales are simply aren’t even close. The only scenario in which one might want to mix the two scales would be if they wanted to use the 1:72 figures as halflings.
If you’re looking for something you can use with 28mm figures, look instead for something between 1:43 and 1:56 or O scale.
Bolt Action is good proof of this: Warlord’s figures are 28mm and their vehicles are Italeri 1:56 models. To my tastes, I find the vehicles on the small side, but some of that is caused by Warlord’s heroic scale proportions (the pumpkin-sized heads and baseball mitt-sized hands I prefer).
The tank on the left is a 1:56 Company B Sherman Tank, with a Warlord/Italeri tank driver sticking out of the the top. Compare the size on the head of the tank driver, who is 1:56, to the 28mm Warlord Marines. The car on the right is a 1:43 Greenlight Fast & Furious Dodge Charger.
When it came time to buy some trucks for my Bolt Action French Resistance, I picked up some Welly/Ledo models: the one on the left is (I believe) a 1:64 Ledo Days Gone truck and the one on the right is the same vehicle, but in 1:43 and manufactured by Welly. The former is clearly too small and the latter just right.
I don’t have any 1:72 cars or tanks, but I believe this is a 1:72 Mustang next to a 28mm Warlord Marine. Compare the size of the heads.
So: 1:56 is close enough but on the small side, 1:43 is close enough but on the large side. 1:72 is just all wrong.
I hope this is helpful, and that person who’s trying to math their way into proving that 1:72 is, indeed, close enough to use with 28mm miniatures (there’s always at least one); I’m sure they’re well-intentioned but they don’t know what the hell they’re talking about.