Average Calculator
Mean · Weighted · Grade · Moving Average
Enter each value with its weight. Blank rows are ignored. Weight cannot be 0.
Enter each grade (%) with its credit hours. Blank rows are ignored. Credits cannot be 0.
An average calculator gives you the "typical" value in a set of numbers in one click — but "average" actually covers four different calculations: the simple mean, a weighted average, a grade average, and a moving average. This tool below handles all four, and the guide underneath explains exactly how each formula works, with worked examples you can check by hand.
What Is an Average, Exactly?
An average is a single number that represents the "typical" value inside a larger set of numbers. In everyday language, "average" almost always means the mean — add everything up, divide by how many values there are. But statisticians use "average" as an umbrella term that also covers the median (the middle value) and the mode (the most frequent value). Each measures the center of your data slightly differently, and picking the wrong one can genuinely mislead you — a single very high or very low number can pull the mean far away from what most of your data actually looks like.
How to Calculate an Average (Step by Step)
The arithmetic mean formula is the one most people mean when they say "calculate the average":
Average = (Sum of all values) ÷ (Number of values)
Worked example: Five quiz scores — 72, 85, 90, 68, and 95.
- Add them: 72 + 85 + 90 + 68 + 95 = 410
- Count them: 5 scores
- Divide: 410 ÷ 5 = 82
That's it — the average quiz score is 82. Type the same five numbers into the Simple Average tab above and you'll get the identical result, plus the median, mode, and range for free.
Mean vs Median vs Mode vs Range — What's the Difference?
| Term | What it measures | Best used when |
|---|---|---|
| Mean | Sum ÷ count | Data is fairly evenly spread, no extreme outliers |
| Median | The middle value when sorted | Data has outliers (e.g. incomes, home prices) |
| Mode | The most frequent value | You want the most common outcome, not a calculated one |
| Range | Highest value minus lowest | You want to see how spread out the data is |
A quick gut-check: if one value in your set is wildly different from the rest, the mean will shift toward it — the median usually won't. That's exactly why household income statistics are almost always reported as a median rather than a mean. For a deeper walkthrough of these formulas, Khan Academy's mean, median and mode review is a solid free reference.
How to Calculate a Weighted Average
A simple average treats every number equally. A weighted average gives more influence to values that matter more — a value with a weight of 3 counts three times as much as a value with a weight of 1.
Weighted Average = Σ(value × weight) ÷ Σ(weight)
Worked example: Say your portfolio holds a stock worth $50 (weight: 10 shares) and another worth $80 (weight: 5 shares).
- Multiply each value by its weight: (50 × 10) + (80 × 5) = 500 + 400 = 900
- Add the weights: 10 + 5 = 15
- Divide: 900 ÷ 15 = $60 — your true average cost per share
Plug those same figures into the Weighted Average tab and you'll see the identical $60 result. This same formula is what spreadsheet tools use behind a `SUMPRODUCT`-style weighted average in Excel.
How to Calculate a Grade Average
A grade average — sometimes loosely called a GPA-style average — is really just a weighted average where the "weight" is credit hours instead of shares or units. A 4-credit course that you scored 95% in should count for more than a 1-credit elective you scored 70% in, and a straight (unweighted) average would treat them as equal.
Worked example: Course A: 88% (3 credits). Course B: 74% (4 credits). Course C: 95% (2 credits).
- (88 × 3) + (74 × 4) + (95 × 2) = 264 + 296 + 190 = 750
- Total credits: 3 + 4 + 2 = 9
- 750 ÷ 9 = 83.3%, which typically maps to a B letter grade
| Percentage range | Typical letter grade |
|---|---|
| 90–100% | A |
| 80–89% | B |
| 70–79% | C |
| 60–69% | D |
| Below 60% | F |
Grading scales vary by school, so treat the letter shown in the Grade Average tab as a general guide rather than an official transcript conversion.
What Is a Moving Average? (And Why It's Different)
A simple average collapses a whole data set into one number. A moving average (also called a simple moving average, or SMA) does something different: it recalculates the average continuously as new data comes in, using a fixed "window" of the most recent points. That's why it's the standard tool for spotting trends in noisy data — stock prices, exchange rates, website traffic — where a single overall average would hide short-term swings entirely.
Worked example: Daily values: 10, 12, 9, 14, 16 with a 3-day period.
- Window 1 (days 1–3): (10+12+9) ÷ 3 = 10.33
- Window 2 (days 2–4): (12+9+14) ÷ 3 = 11.67
- Window 3 (days 3–5): (9+14+16) ÷ 3 = 13.00
Notice the average "moves" forward one step at a time — hence the name. Traders commonly watch 50-day and 200-day moving averages to judge whether a price trend is strengthening or weakening; see Nasdaq's moving average glossary entry for the finance-specific definition. The Moving Average tab above runs this exact calculation for any period you choose.
Real-Life Examples of Averages
Averages show up in far more places than school and stats class:
- Average monthly take-home pay: if your net pay varies month to month (bonuses, overtime, tax withholding changes), averaging the last six payslips gives a more realistic budgeting number than any single month. If you want the underlying net-pay figures first, sitnit.com's UK Take-Home Pay Calculator works out your monthly net pay from gross salary and tax code.
- Weighted average of recurring contributions: if you're comparing take-home pay across countries or contract lengths, run each period through the Netherlands Salary Calculator or Singapore CPF Calculator, then use the weighted average tab above to blend unequal periods (e.g. 8 months at one rate, 4 months at another) into a single accurate annual average.
- Average exam or coursework grade: the Grade Average tab handles the credit-weighted version of this directly.
- Moving average of a savings balance or stock price: the Moving Average tab smooths out the noise so you can see the actual trend.
Common Mistakes When Calculating Averages
- Treating the median as the mean. They only match in perfectly symmetrical data — for income, home prices, and most real-world financial data, they diverge.
- Forgetting to weight unequal groups. Averaging "average of averages" (e.g. averaging three class averages that had different numbers of students) without weighting by class size gives a distorted result.
- Letting outliers dominate. One extreme value in a small data set can swing the mean dramatically — check the range and median alongside the mean before trusting it.
- Using the wrong moving-average period. A 5-day window reacts fast but is noisy; a 200-day window is smooth but slow to reflect new trends. Pick the period based on how quickly you need the signal to react.
- Rounding too early. Rounding intermediate values before the final division compounds small errors — round only your final answer.
Frequently Asked Questions
Conclusion
"Average" is rarely just one calculation. Use the simple mean for evenly spread data, switch to a weighted average whenever some values matter more than others (grades, portfolio holdings, blended pay periods), and reach for a moving average whenever you're tracking a trend over time rather than summarizing a fixed data set. Bookmark this page — all four calculators above are free to use as often as you need.