Recalculate GPA after replacing a grade.
GPA is quality points divided by credits, where quality points are grade points times credit hours. Grade replacement leaves the credit total unchanged and swaps one attempt's quality points for another's, so the effect is the credit-weighted difference between the two grades spread across all your credits. Replacing a D with an A- in a three-credit course across sixty credits moves the GPA by about 0.135 — real but modest, which is why replacement matters most early in a degree when the credit base is small.
Quality points
Quality points = GPA x credits completed
After replacement
New GPA = (quality points - old grade x course credits + new grade x course credits) / credits completed
No. Almost all institutions keep the original attempt visible and only exclude it from the GPA calculation, usually flagged as replaced or excluded.
Because the change is diluted across every credit you have taken. The same replacement that moves a 30-credit GPA by 0.27 moves a 120-credit GPA by less than 0.07.
Similar in effect but usually more restricted — often limited to a set number of courses, to grades below C, and to retakes taken at the same institution. Check the registrar's policy before relying on it.