What happens when a funeral home has a need for an unusual size casket, i.e., for a baby or a very large size person. Do funeral homes usually keep these in their stock, or must they be special ordered from a manufacturer?
Not based on an particular knowledge, but infant deaths are very common, so I doubt those deaths would be problematic from a logistical point of view.
When an infant relative passed away last year the funeral home had a suitable casket in stock. One sad data point.
Yep, the infant casket is a heart wrencher. I had a cousin who passed just before full term. Sadly, my aunt and uncle had to name him, buy a plot, and bury him.
Ditto, my cousins who had to bury their daughter of two days a few years back. 
Hugs to all of you who have been involved in any way in an infant death.
I would imagine that, in the event that a person who is extremely tall and/or obese dies, the funeral home can order an appropriately-sized casket from some kind of central warehouse, and have it shipped overnight.
Do you mean burial-style nice caskets or the plywood box-type caskets meant for cremation? As already mentioned, the funeral business seems quite orderly and well-organized (they better be for the prices they charge), and most wouldn’t have a problem to quickly order/ship in whatever sized casket they’d need very quickly. Depending on the general physical size of the local population, some homes might well keep a few plus-sized cheap cremation caskets on hand, but maybe not the expensive burial versions.
Caskets are available in different styles, price points and finishes (e.g., walnut vs maple vs oak). I can’t imagine the average funeral home stockpiles all the different ones available. So I assume they operate like my tire dealer does; stock the most common types but other types are available on short notice from a warehouse or the manufacturer.
For a straightforward cremation of a child here, many funeral directors will do the job with no charge. The Crem or cemetery will charge but most clergy (if required) will also waive the fee. Sadly small coffins are a regular requirement, but there is also an increasing need for very large ones which have to be made to order.
Data point: the casket for a baby less than 3 years old is usually more expensive because of the size re: supply and demand.
My morbidly-obese cousin wouldn’t have fit into any of those. Her casket had to be custom made … and the grave had to be dug wider.
Not taking issue with you Saint Cad but if that’s indeed the case, it’s yet another example of the funeral home industry taking advantage of people at their most vulnerable. Mortality rates and statics aren’t that difficult to come by, and the average funeral home shouldn’t be caught in a supply and demand issue barring a significant natural disaster.
The best thing my parents ever did was to make their own arrangements with a clear head years in advance. No snap decisions. No mourning. No guilt. No “I have to spend $7,000 on a casket for mom.” By the time I’d heard the “I’m sure you want only the finest for your loving mother” for the third time I wanted to punch the guy in the forehead. I went with the very basic items my parents laid out and I’ve never regretted it.
The American way of death from suicide, to nursing homes to funerals is gooned up.
For my mother passed away she made sure to let me know not to spend any money on her dead body. The crematorium offered me a $50 cardboard box, and I took it.
I want one of those. Think of it like economy-plus or business class seating for a very long trip. 
In 2004 I interviewed for a systems analyst/network administrator job with the Bates Casket Company (division of Hillenbrand Industries) of Batesville, Indiana. When I learned that Batesville was “about equidistant from Louisville, Cincinnati, and Indianapolis” I passed on the offer. Or maybe when I asked if there was a Bates Motel in town!