Labelling
Why two sources give different figures for the same item
Databases, apps and operator sites routinely disagree. The disagreement is usually explicable and the resolution rule is simple.
Anyone who has checked the same menu item in two places has found two different numbers. The gap is rarely error in the ordinary sense. It comes from the sources describing slightly different things.
Different builds
The most common cause. One source describes the item as sold in one market with one bread and one sauce; the other describes a variant. Neither is wrong about its own subject. They are not describing the same food.
Different vintages
Third-party databases are refreshed on their own schedule, and often inherit entries from older versions of themselves. An entry can sit unchanged for years after the operator reformulated the product. Dates on database entries are frequently the date the entry was edited, not the date the figures were valid.
User-contributed entries
Several widely used food apps allow users to create entries, and those entries persist and get reused. A popular user entry can outrank the operator's own figures in an app's search results and look equally authoritative. It carries no verification at all.
Calculated against measured
Some figures are laboratory analyses of a prepared item. Others are calculated by summing ingredient values from reference tables. The two methods legitimately differ, particularly for cooked items where fat is absorbed or lost in preparation.
Rounding bands
Labelling rules permit rounding within defined bands, and different jurisdictions permit different bands. The same underlying value can be presented as two different published numbers without either being inaccurate.
The resolution rule
Prefer the operator's own current published figures for your own market, and treat everything else as an approximation. Where the operator publishes nothing, the figure is unknown. Unknown is a legitimate answer and a more useful one than a confident number from a source that cannot say where it came from.