Weighted Average Calculator | Grades & Portfolio

Quick Start Guide

  1. Select mode: Use Simple, Templates, or Bulk Paste mode.
  2. Add rows: Enter Value and Weight for each row.
  3. Review output: See weighted mean and contribution breakdown.
  4. Compare scenarios: Adjust weights to understand sensitivity.
  5. Export result: Save outputs for reporting or review.

Understanding Weighted Mean

Weights don't need to sum to 100

The formula divides by the actual total weight you entered, so it works correctly whether your weights are percentages that happen to add to 100, credit hours, sample sizes, or any other scale — 3 and 1 (total 4) produce the exact same result as 75 and 25 (total 100), because the ratio between weights is what matters, not their sum.

Weight percentages and what each row contributes

Weights rarely arrive as percentages — a syllabus says 3 credits, a portfolio says $40,000, a survey says 812 respondents — so the calculator converts them for you. Two rows weighted 3 and 1 are 75% and 25% of the total, and it reports both that share and the contribution each row makes to the final figure. Scoring 85 at weight 3 and 92 at weight 1 gives a weighted mean of 86.75, and the first row contributes 63.75 of that: three quarters of the weight doing roughly three quarters of the work. Seeing the split matters when you are deciding where effort actually moves the number, which a bare average will never tell you.

Simple / Templates / Bulk Paste

These are three ways to get the same rows into the same calculation — Simple for typing rows one at a time, Templates for common presets (course grades, portfolio allocation, survey segments), and Bulk Paste for pasting many rows from a spreadsheet at once. None of them change the math.

Reading the contribution breakdown

Each item's contribution is (Value × Weight) ÷ Total Weight — the portion of the final mean that item is responsible for. An item can have a high contribution either because its value is large or because its weight is large; the breakdown separates the two so you can see which is driving the result.

What this calculator does not cover

This calculates one weighted average from value/weight pairs — it does not apply grade-replacement policies or track history across sessions. For a course-grade-specific version with a target-GPA planner, see the GPA Calculator.

Features

Multiple Entry Modes: Add rows one at a time, load a preset template (course grades, portfolio, survey), or bulk-paste CSV/TSV rows copied from a spreadsheet.

Weight Summary: Shows total weight and flags whether it already sums to 100 — weights don't need to.

Contribution Analysis: See how each row shifts the overall mean.

Biggest Mover: Highlights the row driving the result hardest, and what it contributes.

GPA Handoff: Send a weighted result straight to the GPA Calculator in one click.

Export: Save the mean and the per-row breakdown as JSON, CSV or PDF.

Common Use Cases

Academic Grades: compute weighted course averages, adjusting exam and homework weights quickly.

Survey Analysis: weight responses by cohort size, confidence, or population share for representative averages by segment.

Portfolio & Business Metrics: calculate weighted investment returns by allocation, or weighted pricing and cost signals, and export insights to decision decks.

Price Index: weight goods and services by importance for economic index calculations.

Frequently Asked Questions

The calculator works it out and shows it per row, so you do not have to normalise anything by hand. Weights of 3 and 1 become 75% and 25%; weights of 40,000 and 10,000 become 80% and 20%. It also reports what each row contributes to the final mean in absolute terms — with 85 at weight 3 and 92 at weight 1 the mean is 86.75, of which 63.75 comes from the first row. Weights never need to add up to 100 for this to work.
Use weighted mean when some values contribute more to the final result than others — like grades (credit hours matter) or investment portfolios (position size matters). A simple average treats all values equally; a weighted average multiplies each value by its weight, sums the results, then divides by the total weight. Example: a 3-credit A and a 1-credit B gives a weighted average of 3.75, not the simple average of 3.5.
Weighted mean = Σ(value × weight) ÷ Σ(weight). Multiply each value by its weight, add those products together, then divide by the sum of all the weights. For values 80, 90, and 70 with weights 2, 3, and 1, the weighted mean is (160 + 270 + 70) ÷ 6 = 83.3. The calculator shows each row’s contribution so you can see how the weights drive the result.
Enter each course grade as a value and its credit hours as the weight. For example, value=4.0 (A), weight=3 credits. Add all courses and the calculator computes your GPA-style weighted average automatically.
The calculator works with any weight distribution — weights don't need to sum to 100. The formula divides by the actual total weight you entered, so relative weight still matters correctly whether your weights are percentages, credit hours, sample sizes, or any other scale. The result panel shows your total weight and notes when it happens to equal 100.
Yes — switch to Bulk Paste mode and paste rows copied from a spreadsheet or CSV file. One value/weight pair per line, separated by a comma, tab, semicolon, pipe, colon or plain space, so most copied columns paste in without reformatting. Rows missing a weight, or carrying one of zero or less, are skipped and the toast tells you how many.
The contribution breakdown shows how much each row contributes to the final weighted mean — calculated as (Value × Weight) ÷ Total Weight for that row. Items with higher values and weights contribute more; the breakdown separates the two so you can see which is driving the result and spot outliers.

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