Cost per unit calculator

A workshop starts 10,000 widgets, scraps 4% and ships 9,600. Manufacturing cost per good unit is $16.46, variable cost is $13.66, and fully loaded cost with selling and administrative costs is $20.95. At a $29.00 price that is $8.05 of profit per unit. If volume falls by half, the fully loaded cost rises to $28.24 and the profit almost disappears. Break-even is 4,563 good units.

One formula gives several different answers, and each is right for a different decision. This calculator shows the three side by side, then puts them to work: scrap, a unit cost curve across five volumes, break-even units, and the price that delivers your target margin.

Who reaches for this

The calculator takes one product and one period. It asks for units started, the scrap rate, variable cost per unit started for materials, labor and variable overhead, fixed manufacturing overhead, fixed selling and administrative cost, the variable selling cost per unit sold, and a price. From those it builds three unit costs, the contribution margin, break-even volume, and the price that gives your target margin.

Two features go beyond the formula every competing page shows. The unit cost curve reruns the same plant at 50%, 75%, 100%, 125% and 150% of your volume, so you can see how much of today’s cost per unit is really a volume effect. And the scrap input divides by good units, not units started, because a spoiled unit costs the same as a good one and only the good ones can be sold.

People say “cost per unit” as if it were one number. It is at least three, and choosing the wrong one is the most common reason a unit cost misleads.

Here is how the example builds. Variable manufacturing cost is $11.00 per unit started ($6.00 of materials, $3.50 of labor and $1.50 of variable overhead), so 10,000 started units cost $110,000. Add $48,000 of fixed manufacturing overhead for a total of $158,000, and divide by 9,600 good units to get $16.46. That is the figure that goes on the balance sheet as inventory cost, because financial reporting under U.S. GAAP and IFRS uses absorption costing.

Variable cost is $110,000 ÷ 9,600 = $11.46 plus $2.20 of shipping and fees, or $13.66. It is the cost that a decision to make and sell one more unit actually triggers, so it is the number to use for a special order or a discount. Fully loaded cost adds $22,000 of fixed selling and administrative cost to the numerator, $180,000 in all, giving $18.75 per good unit plus $2.20 of selling cost, or $20.95. It is the floor for a price you can sustain, since a price that does not cover it leaves fixed costs unpaid.

Which one to use

A special order, priced two ways

A customer offers $18.00 a unit for 2,000 extra units, well below the $20.95 fully loaded cost. Judged on the fully loaded figure, the order loses $2.95 a unit. Judged on the variable cost of $13.66, it adds $4.34 a unit, about $8,700 in total, provided the plant has spare capacity, so fixed costs do not change, and provided the order does not lead regular customers to ask for the same price.

Both readings are correct, and they answer different questions. The variable view says whether one more order improves this month’s profit. The fully loaded view says whether a business that sold everything at $18.00 would survive. Taking the order is sound when capacity is idle and the price is contained. It is a mistake when it uses capacity that a full-price order would have taken, or when it resets what customers expect to pay.

Fixed costs stay the same in total however many units you make: rent, equipment depreciation, salaried supervision, insurance. Variable costs rise in proportion to output: materials, piece-rate labor, packaging, shipping. The unit cost of a variable cost is constant, and the unit cost of a fixed cost falls as volume rises. That is the whole reason larger runs are cheaper per unit.

Fixed cost per unit is $70,000 divided by good units, so it is $14.58 at half the volume and $4.86 at one and a half times. The variable part of the cost, $13.66 per unit, does not move. Profit per unit falls from $8.05 to $0.76 when volume halves, which is a drop of 90% from a 50% decline in volume. That effect cuts both ways, and it is why a business with high fixed costs is so sensitive to a slow month.

Average cost and marginal cost

The cost per unit from the formula is an average. It spreads everything, including fixed costs, over every unit. The marginal cost is what one more unit adds, and in the short run that is just the variable cost, $13.66 here. The two answer different questions. Average cost tells you whether the product pays its way over a year. Marginal cost tells you whether one more order adds to profit this month.

The relevant range

Fixed costs are fixed only within a range of activity. Doubling output may need another shift, a second machine or a larger building, and each of those steps the fixed cost up. The curve in the table assumes one plant’s fixed costs hold from 50% to 150% of volume. That is a fair assumption for a moderate range and a poor one for large swings, so treat the outer rows as approximations and check where a new fixed cost would begin.

Reading unit cost over time

A cost per unit that moves from one month to the next has two possible sources, and they call for different responses. The variable part changes when prices or usage change. The fixed part changes when volume changes. Split the movement before reacting to it. If volume falls from 100% to 75% in the example, fully loaded cost rises from $20.95 to $23.38, an increase of $2.43. All of it comes from fixed cost per unit, which goes from $7.29 to $9.72, and none from variable cost, which stays at $13.66.

A manager who sees only the total may go looking for a cost problem on the floor. A manager who sees the split knows the floor is on standard and the issue is demand. The reverse case matters as much: a variable cost per unit that creeps up while volume is steady points to material prices, scrap or labor efficiency, which is where the variances on the standard cost page come in.

A spoiled unit costs as much to make as a good one and cannot be sold. Its cost is spread across the units that can. Dividing total cost by units started understates cost per unit, and dividing by good units gets it right. In the example, 10,000 units are started and 400 are scrapped, so $158,000 of manufacturing cost is spread over 9,600 units, not 10,000.

With no scrap, fully loaded cost would be $20.20. With 4% scrap it is $20.95, an increase of $0.75 or 3.7%, and the profit per unit falls from $8.80 to $8.05. Scrap also changes break-even. The plant must start 4,753 units to sell 4,563 good ones. The variable cost per unit started is $11.00, but the variable cost per good unit is $11.46, because each good unit carries its share of the scrap.

Normal scrap, the kind that happens in any process, is part of the product cost. Abnormal scrap from a machine failure, a bad batch of material or an operator error is usually treated as a loss for the period and not spread over the good units. The distinction matters for reporting, and it matters for management, since abnormal scrap should be investigated and not built into the standard.

Cost per unit is the starting point for two pricing questions. What volume do I need to break even at this price, and what price do I need at this volume for the margin I want?

Break-even volume is fixed cost divided by contribution margin per unit. The contribution margin is the $29.00 price minus the $13.66 variable cost, or $15.34, which is 52.9% of the price. Fixed costs are $70,000, so break-even is $70,000 ÷ $15.34 = 4,563 good units. Below that the plant loses money, and every unit above it adds $15.34 of profit. The contribution margin calculator and the break-even point page take the analysis further.

The price for a target margin comes from the fully loaded cost. To earn a 30% margin on price, divide $20.95 by (1 − 0.30), which gives $29.93. That is $0.93 above the current price, so the plant earns a 27.8% margin today, not 30%. A margin on price is not the same as a markup on cost. A 30% margin needs a 42.9% markup, and the markup vs. margin calculator converts between them.

One caution: the price for a target margin assumes the volume you entered. If the price rise cuts sales, fixed cost per unit rises, and the margin you targeted moves. That is why the calculator shows the curve and the price together.

With one product, fixed costs go straight to it. With several, shared costs such as rent, supervision and equipment have to be split, and the split is a choice. The same total cost gives different unit costs depending on the base.

A shop makes 500 tables and 1,000 chairs. Table variable cost is $17,000 and chair variable cost is $16,000. Shared fixed cost is $10,000, tables take 1,500 labor hours and chairs 500, and tables sell for $80 and chairs for $40. Spread the $10,000 three ways.

A table costs between $40.67 and $49.00 and a chair between $18.50 and $22.67, from the same factory and the same total cost. By units, the table looks like the more profitable product. By labor hours, the chair does. Neither is wrong, because each rests on a different belief about what drives the shared cost. If most of the fixed cost is skilled supervision that follows labor, hours are the better base. If it is warehouse space that follows volume, units are.

The choice belongs to the same family as the overhead rate decision on the predetermined overhead rate calculator, where machine hours and labor hours gave opposite answers for the same two jobs. Whatever base you choose, use it consistently, and check the product mix before dropping a product on the strength of an allocated loss. Allocated costs do not disappear when a product does.

Job costing tracks each order. Process costing suits continuous production of identical units, such as chemicals, bottled drinks or bricks, where costs are accumulated by department and averaged. Its complication is unfinished units at period end. A unit that is half-made has absorbed only part of the cost, so counting it as a whole unit overstates the output.

The fix is equivalent units. Say a department starts 10,000 units, completes 8,000, and has 2,000 in process at period end. The 2,000 are 100% complete for materials, which are added at the start, and 40% complete for conversion, meaning labor and overhead. Materials cost $60,000 and conversion cost $70,400.

A completed unit costs $6.00 plus $8.00, or $14.00, so the 8,000 completed units carry $112,000. The ending inventory carries 2,000 × $6.00 for materials plus 800 equivalent units × $8.00 for conversion, or $18,400. The two add to $130,400, which is the $60,000 plus $70,400 the department spent. The check matters: every dollar must land in either the finished units or the unfinished ones.

Many manufacturers do not compute cost per unit from the period’s actual costs. They set a standard cost per unit in advance, from a standard quantity and price for each input, and compare actual results with it. The standard cost card on the standard cost variance calculator shows the structure, and the variances explain why the actual unit cost differs from the standard.

Overhead is the piece that needs a rate. Fixed overhead per unit turns on the volume you assume, which is why a predetermined overhead rate divides the budget by an estimated activity level. Using a different denominator changes the unit cost of every product even though nothing on the floor has changed. The unit cost in this calculator uses actual good units, which is the simplest case. A plant using a rate applies overhead at the rate and reports the difference from actual as a variance.

Cost per unit in a service business

The same structure works for a consultant, a tradesperson or an agency, with billable hours as the unit. Suppose fixed costs of $60,000 a year cover an office, software and insurance, and variable cost is $10.00 per billable hour. At 1,200 billable hours, cost per hour is $60,000 ÷ 1,200 + $10.00 = $60.00. At 1,600 hours it is $47.50. The hourly rate has to clear that number before it pays the owner anything, and utilization moves it as much as any cost cut would.

Cost per unit for a reseller

A seller who buys and does not make still has a unit cost, built from different pieces. Say a product costs $12.00 to buy, with $1.50 of inbound freight, 5% duty ($0.60), $2.75 for picking, packing and outbound labels, and a marketplace fee of 13.6% on a $35.00 price ($4.76) plus a $0.40 order fee. The unit cost is $22.01 and the profit is $12.99. The eBay fee calculator and the landed cost calculator fill in the fee and freight lines for a specific sale.

Four levers move unit cost: volume, yield, input prices and efficiency. Each has a different effect and a different cost of pulling it. Here is what each is worth in the example, where the starting fully loaded cost is $20.95.

Volume is the largest lever and the least certain, since it only helps if the extra units sell at the same price. Cutting fixed costs by 10% is worth $0.73 and it is the one that is fully within management’s control. Scrap improvements are worth more when the material is expensive, and input price cuts work at every volume. The point of the table is to rank the options before spending on any of them. A project that saves $0.29 a unit on 9,600 units is worth about $2,800 a year, so its cost should be compared with that figure.

Some levers trade against each other. Cheaper materials can raise scrap, as the material price and usage variances on the standard cost page show, and a larger batch lowers fixed cost per unit and raises inventory. The inventory turnover calculator shows what that inventory costs to carry, and the landed cost calculator does the equivalent for goods that are bought in and not made.

Continue with the predetermined overhead rate calculator or the standard cost variance calculator.