Word for one too many items

Perhaps this word doesn't exist. I'm looking for the word to describe the last final thing you want to put in a container but it won't fit. There is always one of those. You have ten items but always only nine will fit into the container you have. Often occurs with a toolbox which has one too many tools to go into it.

Solution 1:

How about excess? The OED gives as one example of its usage:

excess luggage: luggage over the weight for which a passenger is allowed free carriage.

The meanings are broader than what you are looking for but I think the meaning you want is one of the meanings of excess.