Is OO the same as HO?

[oldline2]

How far off are OO and HO scales from each other? I saw some nice Bachmann models in the UK section and would like to add a couple. Compatible?

Thanks,
oldline2

[Len]

HO is 3.5mm = 1ft (1/87 scale), while OO is 4mm = 1ft (1/76 scale). Both operate on the same 16.5mm gauge track.

Len

[ACY]

OO scale is primarily used in England. OO scale track is 16.5 mm which would scale out to 4 feet 1.5 inches; however, this is 7 inches under scale or approximately 2.33 mm too narrow.
OO scale came about because early motors would not fit inside 1:87th English models so they increased the size to 1:76th scale to have enough space for the motor but uses HO scale track because that was the closest size in mass production (in large part due to its popularity in the US).
Keep in mind that the locomotives and wagons/coaches will have English style couplers that will not mate with US couplers. Also keep in mind that English structures and scenery are often built to 1:76th scale to match the trains while US structures, people, cars et al would be undersized.
Also some OO scale locomotives have decoders that use a proprietary command system that does not meet NMRA standards that would require their control system to operate the locomotive.

[oldline2]

Thanks for the clarification on the differences. Close but no cigar!

I saw the engines on the UK site and thought I'd like to have a Black 5 and a Decapod just for something different. Converting the couplers and all wouldn't be a big deal. I'd hate to ahve to change out any decoders, etc but whatever.

Thanks, again.
oldline2

[ACY]

I'd hate to ahve to change out any decoders, etc but whatever.

Bachmann UK's products are all NMRA compliant as far as I know, but a major manufacturer of OO (Hornby) is often not NMRA compliant.
Sorry if I misled you.

[ebtnut]

Just to complicate things a bit, there used to be a domestic OO (Double-Oh) scale at 1:72.  It rose in the late '30's and was popular through the '40's.  Lionel made a line of OO models that were very nice for the period. The track gauge was 0.75", and the wheel and flangeway standards were the same as for HO.  Some enterprising early O scale modelers noted that the track gauge was three feet in O scale, and began using OO mechanisms, wheels, trucks and track to build On3 models.  If you look at an NMRA standards gauge for On3, it is actually labeled OO/On3. 

[Trainman203]

American 00 is in the same dustbin as TT scale.

[rogertra]

OO scale is primarily used in England.

The most popular scale in Great Britain/United Kingdom not just in "England".  There is a difference. 

England in a country and does not include Scotland, Northern Ireland and  Wales.

Cheers.

[ACY]

The most popular scale in Great Britain/United Kingdom not just in "England".  There is a difference. 
England in a country and does not include Scotland, Northern Ireland and  Wales.

I am not familiar with what they do in Scotland, Wales and Ireland so I simply said England as I don't know what the rest of the UK does.