Overdelivery is receiving more than you ordered: 1,000 bought, 1,080 delivered. It's deliberate, and it's not generosity so much as engineering: the extra units are a buffer against the small drop both sides know is coming.
Some attrition after delivery is physics: platforms clean continuously. So providers pad orders, commonly by a few percent, so the NET count still meets or beats the purchased figure once things settle.
It pre-pays the smallest refill claims and keeps charts right without support tickets. The practice is standard enough that exact-to-the-unit delivery is itself a tell of a very automated pipeline.
Mild surplus: normal, mildly good news. Enormous surplus is information too: it implies the provider expects a serious drop and is buying room in front of it.
Either way, judge the order where it counts: the net number a month later against what you paid. Overdelivery is the industry quietly admitting averages; your chart audits the admission.
Precision cases exist: hitting an exact milestone number, or keeping ratios tuned. If the exact figure matters to you, say so in the order notes or pick services listed with tight delivery; most buyers, most of the time, are better served by the buffer.
Deliberate overdelivery: a few percent extra as a buffer against normal early drop. You were not charged for the surplus.
A small buffer is standard good practice. A huge one hints the provider expects heavy drop from that stock, which tells you the grade.
No: you pay the listed price for the ordered amount. The buffer is the provider managing its own refill liability.
Related terms
Every definition lives in the full glossary, and the services behind the vocabulary are on the services page.