Enter the total cost and the total number of units sold into the calculator below. The calculator will evaluate and display the average cost per unit sold.
Average Cost Formula
The calculator uses one of three formulas depending on the mode you select.
Fixed + Variable mode
Average Cost = (Fixed Cost + Total Variable Cost) / Units
Total ÷ Units mode
Average Cost = Total Cost / Total Units
Weighted Buys mode
Weighted Average Cost = Σ(Price × Quantity) / Σ(Quantity)
- Fixed Cost: costs that do not change with output (rent, equipment, salaries).
- Variable Cost: costs that scale with output (materials, per-unit labor, packaging). Enter as $/unit or as a total.
- Units: number of units produced or purchased. Must be greater than zero.
- Price: cost per unit on a single purchase.
- Quantity: units bought at that price.
All three formulas return cost per single unit. The result ignores taxes, shipping, and discounts unless you build them into the inputs. For weighted mode, simple averaging of the prices is wrong when quantities differ; you must weight by quantity.
Reference Tables
Use these to sanity-check your inputs and interpret the output.
| Mode | Use When | Common Use Case |
|---|---|---|
| Fixed + Variable | You produce something and know setup vs per-unit costs | Manufacturing, print runs, baking, custom orders |
| Total ÷ Units | You already know the lump total and quantity | Receipts, project totals, bulk orders |
| Weighted Buys | You bought the same item at different prices | Stock cost basis, inventory restocks, dollar-cost averaging |
| Result Pattern | What It Tells You |
|---|---|
| Average cost falls as units rise | Fixed costs are spreading across more output. Standard economy of scale. |
| Average cost ≈ variable cost per unit | Fixed cost is small or volume is high. Pricing must beat variable cost to be viable. |
| Weighted average above simple average | You bought more units at the higher price. Larger lots dominate the result. |
| Average cost above selling price | You are losing money per unit. Cut variable cost or raise volume to dilute fixed cost. |
Example
You bake 300 loaves. Oven and rent cost $1,200 for the run. Ingredients and packaging run $2.50 per loaf.
Total variable cost = 300 × $2.50 = $750
Total cost = $1,200 + $750 = $1,950
Average cost = $1,950 ÷ 300 = $6.50 per loaf
If you sell at $8, your margin is $1.50 per loaf. Drop production to 100 loaves and the same $1,200 fixed cost pushes average cost to $14.50, which is above the price. Volume matters.
FAQ
Is average cost the same as average total cost (ATC)? Yes. In economics textbooks, ATC = Total Cost ÷ Quantity, which is what the Total ÷ Units mode calculates.
How is this different from marginal cost? Average cost is the cost per unit across all units. Marginal cost is the cost of producing one more unit. They are equal only when average cost is at its minimum.
Why use weighted average instead of a simple average of prices? Simple averaging treats each purchase equally regardless of size. If you buy 1 unit at $20 and 99 units at $10, the true average cost is close to $10, not $15.
Can I include shipping and tax? Yes. Add them into the fixed cost (one-time fees) or roll them into the per-unit price (proportional charges) before entering values.
