GPA Calculator
Convert letter grades to grade points and calculate your cumulative GPA.
Understanding the Calculation
Percentage calculations involve:
- Base Value: The original or total amount
- Percentage Rate: The proportion expressed as a percent
- Result: The calculated value based on your inputs
Common Formulas
- Finding a percentage: (Part ÷ Whole) × 100 = %
- Finding the part: Whole × (% ÷ 100) = Part
- Percentage change: ((New - Old) ÷ Old) × 100 = % Change
Practical Applications
Use percentage calculations for:
- Financial planning and budgeting
- Academic performance tracking
- Business metrics and KPIs
- Health and fitness goals
- Shopping and discount calculations
How GPA Is Calculated
GPA is a credit-weighted average, not a simple one — a 4-credit course counts twice as much as a 2-credit course.
``
GPA = Σ(grade points × credits) ÷ Σ(credits)
`
| Grade | Points | Grade | Points |
|---|---|---|---|
| A | 4.0 | C | 2.0 |
| A− | 3.7 | C− | 1.7 |
| B+ | 3.3 | D+ | 1.3 |
| B | 3.0 | D | 1.0 |
| B− | 2.7 | F | 0.0 |
Weighted GPA adds a point for AP, IB or honours courses, which is why high-school GPAs
above 4.0 exist. Colleges usually recalculate to their own unweighted scale, so a 4.6
weighted GPA is not directly comparable between schools.The most useful thing this calculation tells you is how hard your GPA is to move. After 90
credits, a single A in a 3-credit course shifts a 3.2 GPA by about 0.03. Early grades matter
disproportionately.
The Four Percentage Questions
Almost every percentage problem is one of these, and mixing them up is the most common
arithmetic error there is:
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | Y × (X ÷ 100) | 15% of 80 = 12 |
| X is what % of Y? | (X ÷ Y) × 100 | 12 is 15% of 80 |
| X is Y% of what? | X ÷ (Y ÷ 100) | 12 is 15% of 80 |
| % change from X to Y | ((Y − X) ÷ X) × 100 | 80 → 92 is +15% |
Percentage Points Are Not Percent
A rate moving from 4% to 5% is one percentage point, and a 25% increase. Both
statements are true and they are not interchangeable — headlines routinely use the smaller
one when reporting a rise and the larger one when reporting a fall.
Increases and Decreases Do Not Cancel
| Start | Change | Result |
|---|---|---|
| 100 | +50%, then −50% | 75 |
| 100 | −50%, then +50% | 75 |
| 100 | −20%, then +25% | 100 |
The reason is that the second percentage applies to a different base. To reverse a −20% you
need +25%, not +20%. This is why a stock that falls 50% must double to break even, and why
"we cut costs 30% then grew 30%" leaves you 9% down.Reversing a Percentage
To find the price before a 20% discount, divide by 0.8 — do not add 20%:
`
before = after ÷ (1 − discount)
$80 ÷ 0.8 = $100 ✓
$80 × 1.2 = $96 ✗
``
The same asymmetry applies to tax, tips, markups and platform fees.