Single Grade GPA Impact Calculator

Knowing how one grade moves your overall GPA tells you where the effort is worth spending. A B in a 4-credit course shifts your average more than an A in a 1-credit course does, and this calculator puts a number on exactly how much.

How GPA is calculated: GPA = Sum of (Grade Points × Credit Hours) / Total Credit Hours Attempted

Grade points on the standard 4.0 scale:

• A+ = 4.0 (some schools: 4.3)
• A = 4.0
• A- = 3.7
• B+ = 3.3
• B = 3.0
• B- = 2.7
• C+ = 2.3
• C = 2.0
• C- = 1.7
• D+ = 1.3
• D = 1.0
• F = 0.0

The impact formula: New GPA = (Current GPA × Current Credits + New Grade Points × New Course Credits) / (Current Credits + New Course Credits)

Example: Current GPA: 3.2 over 45 credits
New course: 3 credits, grade B (3.0 points)
New GPA = (3.2 × 45 + 3.0 × 3) / (45 + 3)
= (144 + 9) / 48 = 153 / 48 = 3.188

Three decimal places, because two is not enough to see the movement. That B moved the GPA by −0.013, which rounds away entirely at 3.19 and is the whole thing you came here to find out.

Key insight: The more credits you have banked, the less any single course can move the number. At 120 credits completed, one 3-credit course is 2.4% of your total, so it can only shift the average slightly in either direction. Early on it is the reverse: with 12 credits behind you, one course is a fifth of your record and moves it hard.

This cuts both ways, and the useful half is often the discouraging one. If you are trying to rescue a GPA late in a degree, the arithmetic is against you, and the honest answer is usually more credits rather than better grades in the few you have left.

What GPA do you need? The result also works backwards, showing the grade this course would have to earn to land you on 3.0, 3.5 or 4.0 overall.