Weighted Average Cost Calculator
The most powerful free weighted average cost calculator for inventory management and procurement. Compute unit costs, batch pricing, supplier comparisons, and inventory valuation with live interactive charts and real-time formula breakdowns.
Cost Data Entry
Cost Presets
Computation Flow
LiveWeight Distribution
LiveValue Comparison
LiveResult Gauge
LiveInventory & Unit Cost Calculator
Enter items to compute weighted average cost per unit.
What Is a Weighted Average Cost ?
Weighted Average Cost in Business
A weighted average cost assigns different importance to each purchase price based on the quantity bought. For example, if you buy 100 units at $5 each and 300 units at $3 each, the weighted average cost is $3.50 per unit — not the simple average of $4. This cost calculator automates the entire process for inventory management and procurement analysis.
Why Simple Average Misleads in Costing
Simple averaging treats all purchase batches equally regardless of volume. If you bought 10 units at $100 and 1,000 units at $10, the simple average shows $55 — but your true average cost is $10.89. The weighted average cost calculator prevents this critical pricing error by factoring in quantities.
Interactive Balance Beam
Drag SlidersHow to Use the Weighted Average Cost Calculator
Enter Cost Values
Type each unit cost or batch price into the 'Value' column — supplier quotes, purchase prices, manufacturing costs, or any cost data you want to average across your inventory.
Assign Quantity Weights
Enter the quantity for each cost. In cost accounting, weights are typically units purchased, batch sizes, or order quantities. The calculator accepts any positive numbers.
View Weighted Cost Results
The weighted average cost calculator computes your result instantly. See the weighted mean cost, sum of products, sum of quantities, and all interactive charts update in real time.
Weighted Average Cost Formula
The Formula Behind Weighted Average Cost
The weighted average cost formula: multiply each unit cost by its quantity, sum those products, then divide by the total quantity. This produces the true weighted cost per unit — not the misleading simple average.
Try the Cost Formula Live
Live Formula — Edit the Values
InteractiveHow the Calculator Computes Weighted Average Cost Step by Step
Inside the Weighted Average Cost Calculator
Costs
Quantities
Step 1: List your items and their quantities
Enter each item cost alongside its quantity. For example: Supplier A $12/unit (500 units), Supplier B $9/unit (800 units), and Supplier C $15/unit (200 units).
Step 2: Multiply each cost by its quantity
The calculator multiplies each cost by its quantity weight. Supplier A: 12 × 500 = 6,000, Supplier B: 9 × 800 = 7,200, Supplier C: 15 × 200 = 3,000.
Step 3: Sum all the products together
6,000 + 7,200 + 3,000 = 16,200. This is the total cost — the numerator in the weighted average formula.
Step 4: Sum all the quantities
Sum the quantities: 500 + 800 + 200 = 1,500. This is the total quantity — the denominator.
Step 5: Divide to get the weighted average cost
16,200 ÷ 1,500 = $10.80/unit. The calculator shows this instantly — the true average cost, not $12.00 (simple average).
Common Cost Calculation Mistakes
Using simple average for unit costs
Averaging unit costs without weighting by quantity produces misleading results. A $100 cost for 10 units and $10 for 1,000 units is not $55. The cost calculator weights correctly.
Dividing by number of batches
Dividing total cost by batch count instead of total units is wrong. The weighted average cost calculator always divides by the sum of quantities.
Confusing costs with quantities
Swapping the unit cost with the quantity produces a completely wrong weighted average. The calculator's labeled columns prevent this mix-up.
Correct costing approach
Multiply each unit cost by its quantity. Sum those products. Sum all quantities. Divide. The weighted average cost calculator automates this entire workflow.
Weighted Average Cost Examples
Inventory Cost Example
Use the weighted average cost calculator to compute true inventory costs. Edit the unit costs and quantities below to see the result update instantly.
The weighted average cost is $10.80, not $12.00 (simple average). Supplier B dominates because they have the largest order quantity (800 units). The cost calculator shows how volumes determine your true cost.
Multi-Supplier Pricing Example
Calculate the weighted average price from multiple suppliers. Edit the costs and order volumes below.
The weighted average cost per kilogram is $8.40, reflecting the blended cost of all materials weighted by the quantity purchased. Steel has the lowest price but the largest volume.
Where Businesses Use Weighted Average Cost
Inventory Valuation
Calculate the true weighted average cost of inventory using the weighted average cost method (AVCO) for accurate financial reporting.
Supplier Comparison
Compare weighted costs from multiple suppliers accounting for different order volumes and pricing tiers.
Manufacturing Costs
Calculate weighted average material costs across production runs, accounting for batch sizes and raw material prices.
Procurement Analysis
Compute weighted average procurement costs across purchase orders where weights represent order quantities.
Important Cost Notes
Quantities must be positive. The cost calculator requires positive weights (quantities or volumes). A weight of zero means the item is excluded from the cost calculation entirely.
Equal quantities = simple average. If every batch has the same quantity, the weighted average cost equals the simple average — same formula, same result. Unequal order sizes are where weighted averages shine.
Weighted cost stays between cheapest and most expensive. No matter how you distribute quantities, the weighted average cost will always be between the lowest and highest individual unit costs.
Larger orders dominate the weighted cost. The larger a purchase quantity relative to the total, the more the weighted cost is pulled toward that batch's unit price. This is the key insight of weighted average costing.
Explore Our Calculator Tools
Fifteen purpose-built weighted average calculators — each tailored to a specific domain with unique inputs, outputs, and interactive visualizations.
Grade Calculator
Calculate your final grade using weighted assignments, exams, and projects.
GPA Calculator
Compute your grade point average across multiple courses.
Weighted Moving Average Calculator
Apply a weighted moving average to time-series data.
Finance Calculator
Portfolio returns, WACC, and investment-weighted metrics with real-time breakdowns.
Cost Calculator
Inventory valuation, unit costs, and supplier comparison with quantity weighting.
Payroll Calculator
Blended pay rates, overtime costs, and department salary analysis by headcount.
Time Calculator
Weighted durations, delivery estimates, and PERT scheduling by task frequency.
Statistics Calculator
Weighted mean, variance, standard deviation, and coefficient of variation analysis.
Mean Calculator
Compute the weighted arithmetic mean from data values with different frequencies or importance weights.
Score Calculator
Compute composite scores from weighted categories for rubrics, tests, and evaluations with letter grades.
Price Calculator
Calculate VWAP, average purchase price, and procurement costs weighted by quantity or volume.
Return Calculator
Compute true portfolio returns by weighting each asset's performance by its dollar allocation.
Rating Calculator
Combine ratings from multiple review sources weighted by review count or credibility.
Interest Calculator
Compute blended interest rates across loans, savings, and credit lines weighted by balance.
Profit Calculator
Analyze blended profit margins across products, services, and segments weighted by revenue.
Weighted Average Cost FAQ
The weighted average cost method (also called AVCO) calculates inventory cost by dividing total cost of goods available for sale by total units available. Each purchase batch is weighted by its quantity, so larger orders have more influence on the average unit cost.
Multiply each unit cost by its quantity, sum all products, then divide by total units. For example: Supplier A ($12 × 500) + Supplier B ($9 × 800) + Supplier C ($15 × 200) = $16,200 ÷ 1,500 = $10.80 weighted average cost per unit.
Use weighted average cost when inventory items are interchangeable and you want a blended cost. Use FIFO (First In, First Out) when tracking specific batch costs matters, such as with perishable goods or items with significant price fluctuation over time.
The calculator works with any numeric values. Convert all costs to the same currency first, then enter the standardized values. The weighted average result will be in your chosen currency unit.
Weighted average cost smooths out price fluctuations across purchase batches. During rising prices, it produces a cost between FIFO (lower) and LIFO (higher), resulting in moderate profit margins and tax implications compared to other inventory methods.