The weekly billing cycle is the fixed week on which Upwork invoices every hourly contract: hours logged in the week are billed when it closes, a review window follows, and the money becomes available after the security period.
Hourly work on Upwork runs to a calendar Upwork sets, not to the contract. All Work Diary time and manual time recorded in a given week is gathered when the week ends, an Upwork invoice is generated for the client, and the client's payment method is charged for the total. During the review window that follows, the client can go through the diary and dispute segments; if nothing is disputed the invoice stands. The freelancer's share, after the service fee, then sits in a pending state through the security period before it can be withdrawn.
The practical effect is a steady rhythm. Hours worked early in a week are paid on the same day as hours worked late in it, so the lag between work and available funds varies by up to a week plus the security period. Time logged after the cut-off falls into the next week's invoice, which catches people out at the end of a contract.
The cycle is also the unit of the weekly hour limit: the cap resets with each billing week, and hours above it in any one week are not invoiced. Upwork publishes the day and time the week closes and the length of the review window in its Help Center; both are Upwork's to change, and fixed-price contracts follow a different timetable based on milestones.
How Upwork Insights uses it
This term describes Upwork's own rules or product rather than a figure the index measures; the pages that do carry live figures are the stats and rate pages.