A simple weighted GPA calculator. Enter each course with a letter or percentage grade and its credit hours, and tag it Regular, Honors or AP/IB. It shows a weighted or unweighted GPA, with a worked example and a show-the-math section.
It is free with no signup. Defaults add 0.5 for Honors and 1.0 for AP/IB, capped at 5.0, and you can edit them. You can add a prior cumulative GPA and credits, then copy a summary, print or reset. It runs in the browser. The page labels results an 'Unofficial estimate' and says it is not affiliated with any school or the College Board.
Jeff Zhaofu kept working out weighted GPA on paper for school courses and found the credit math easy to get wrong. This page is a quick way to type in grades and credit hours and see the result.