Weeks forward and weeks back
Counting in weeks has one convenience and one trap. The convenience: seven divides evenly into the week, so the answer always lands on the same weekday as today — which is the quickest way to sanity-check any of these. The trap: the ISO week number of the result is not simply this week's number plus N, because a year has either 52 or 53 ISO weeks and the boundary does not sit where the calendar year does.
Each page here gives the exact date, the ISO week number of the result, whether it crosses a year boundary, the day equivalent and the business-day equivalent. Where the result lands in ISO week 1 of a year that has not started yet — a real and genuinely confusing case — the page says so and links to the week number calculator.
What is not here
Week counts have an obvious medical adjacency, and this site does not go anywhere near it. There is no health content here at any point, in any family, and there never will be — a question about a person's health belongs with a clinician, not with a date calculator that knows nothing except arithmetic. If that is what brought you here, the count above is all this page can honestly give you.