The weekly hour limit is the maximum number of hours a client allows to be billed on an Upwork hourly contract in one billing week, set by the client and changeable at any time, above which logged time is neither invoiced nor protected.
Every hourly contract carries a limit. The client chooses it in the offer, from a few hours a week to no limit at all, and can raise or lower it from the contract page; a change takes effect from the next weekly billing cycle. The tracker stops recording billable time to the contract once the week's limit is reached, and manual time above it is rejected, so the freelancer cannot run over by accident, only by working off the clock.
The limit is the client's budget control and part of the fine print of Hourly Payment Protection: Upwork guarantees tracked hours within the limit, and nothing above it. A freelancer asked to do more than the limit allows should ask for it to be raised before the hours are worked, not after, because hours logged in a week after the cap is hit cannot be recovered except by a bonus payment at the client's discretion.
It is a cap, not a target. A contract with a forty-hour limit does not oblige the freelancer to work forty hours or the client to pay for them; only logged time is billed. Agencies that staff several members on one contract share the one limit between them. Upwork's Help Center describes how the limit is set and when changes apply.
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.