Everything else is sort of an average that seems about right. Crib blankets & receiving blankets seem to have the biggest variances - there's pretty much every size possible available. I listed the most prevalent. Mattress depths vary widely be manufacturer.
The British thermal unit (BTU or Btu) is a traditional unit of work equal to about 1055 joules. It is the amount of work needed to raise the temperature of one pound of water by one degree Fahrenheit (Physical analogue: one four-inch wooden kitchen match consumed completely generates approximately 1 BTU).
If there is an exact known measure in BTU - British thermal units for energy amount, the rule is that the British thermal unit number gets converted into BOE - barrels of oil equivalent or any other energy unit absolutely exactly.