Difficulty: Intermediate | Prerequisites: Chapter 9 (flexible budgets, activity and spending variances), understanding of variable manufacturing costs (direct materials, direct labour, variable overhead).
Chapter 9 introduced the flexible budget and showed how to separate volume effects from cost-control effects. This chapter zooms in on the cost-control side. Standard costs set specific benchmarks for how much material, labour, and overhead each unit of product should consume and what those inputs should cost. By comparing actual input usage and prices to those standards, managers can pinpoint whether a variance came from paying too much (a price problem) or using too much (an efficiency problem). This is the most granular level of variance analysis in the course.
Standard costs are pre-set benchmarks for the price and quantity of each manufacturing input. Every spending variance from Chapter 9 can be split into a price variance ("did we pay the right amount per unit of input?") and a quantity variance ("did we use the right amount of input?"). The general model uses three columns: AQ x AP, AQ x SP, and SQ x SP. The difference between adjacent columns gives you the price variance and the quantity variance, respectively.
Standard
A benchmark for measuring performance. In cost accounting, standards specify both the quantity of an input that should be used per unit of output and the price that should be paid per unit of that input.
Think of it as: the "should" number, set in advance, against which you measure what actually happened.
Quantity standard (standard quantity per unit)
The amount of direct materials (or direct labour hours, or variable overhead driver) that should be used to produce one unit of finished product. Includes an allowance for normal inefficiencies such as scrap and spoilage.
In simple terms, this is "how much input per unit of output."
Price standard (standard price per unit)
The price that should be paid for each unit of a direct input. For materials, this reflects the final delivered cost. For labour, it includes wages, employment taxes, and fringe benefits.
In simple terms, this is "how much we should pay per unit of input."
Standard cost card
A document that lists, for one unit of a specific product, the standard quantity and standard price of each input, along with the resulting standard cost per unit. It covers direct materials, direct labour, and variable manufacturing overhead.
Think of it as: the recipe card for a product's cost.
Standard hours allowed (standard quantity allowed)
The total amount of an input that should have been used to produce the actual output achieved during the period. Calculated as: actual output x standard quantity per unit.
In simple terms, this is the flexible budget quantity of input.
Price variance
The difference between what was actually paid for an input and what should have been paid at the standard price, multiplied by the actual quantity of the input. Formula: (AQ x AP) - (AQ x SP).
Think of it as: "Did we overpay or underpay for what we bought?"
Quantity variance (efficiency variance)
The difference between the actual quantity of input used and the standard quantity allowed for the actual output, valued at the standard price. Formula: (AQ x SP) - (SQ x SP).
Think of it as: "Did we use more or less input than we should have?"
Spending variance
The total variance combining price and quantity effects. Formula: (AQ x AP) - (SQ x SP). For labour and overhead, spending variance = price variance + quantity variance. For materials, this relationship may not hold exactly (see Core Content).
Materials price variance
The price variance applied specifically to direct materials. Based on the actual units of materials purchased (not necessarily the same as units used).
Materials quantity variance
The quantity variance applied specifically to direct materials. Based on the actual units of materials used in production.
Labour rate variance
The price variance applied to direct labour. It measures whether the actual hourly wage rate differed from the standard rate.
Labour efficiency variance
The quantity variance applied to direct labour. It measures whether actual hours worked differed from the standard hours allowed for the output produced.
Variable overhead rate variance
The price variance applied to variable manufacturing overhead.
Variable overhead efficiency variance
The quantity variance applied to variable manufacturing overhead. Driven by the same activity base as labour (typically direct labour hours).
Standards are set for both price and quantity of each manufacturing input:
Quantity standards specify how much of an input (materials in kilograms, labour in hours, overhead driver units) should be consumed to make one unit of product. These should be tight but attainable, not ideal. They include allowances for normal waste, scrap, and spoilage.
Price standards specify what should be paid per unit of that input: the delivered cost per kilogram of material, the wage rate per hour (including taxes and benefits), or the variable overhead rate per driver unit.
The standard is always set before the period. It represents the cost that a well-run operation should achieve under normal conditions.
A standard cost card summarises the inputs for one unit of finished product. For each of the three variable manufacturing costs (direct materials, direct labour, variable overhead), it shows:
Standard quantity (or hours) per unit
Standard price (or rate) per unit of input
Standard cost per unit = Standard quantity x Standard price
The total standard cost per unit is the sum of all three.
The model uses three columns, each representing a different combination of actual (A) and standard (S) quantities and prices:
Column 1: Actual Quantity of Input at Actual Price (AQ x AP). This is what the company actually spent.
Column 2: Actual Quantity of Input at Standard Price (AQ x SP). A hybrid: the real quantity, priced at the standard.
Column 3: Standard Quantity Allowed for Actual Output at Standard Price (SQ x SP). This is the flexible budget amount for the input.
Variances fall out of the differences between adjacent columns:
Price variance = Column 1 - Column 2 = (AQ x AP) - (AQ x SP). Isolates the effect of paying a different price.
Quantity variance = Column 2 - Column 3 = (AQ x SP) - (SQ x SP). Isolates the effect of using a different quantity.
Spending variance = Column 1 - Column 3 = (AQ x AP) - (SQ x SP). The total of both effects.
A positive result is unfavourable (U); a negative result is favourable (F). Alternatively, if actual exceeds standard, the variance is unfavourable.
For direct materials, the price variance and the quantity variance are often based on different quantities:
The materials price variance is calculated on the actual units of materials purchased.
The materials quantity variance is calculated on the actual units of materials used in production.
Because purchases and usage may differ in a given period (inventory changes), the materials price variance + materials quantity variance will usually not equal the total materials spending variance. This is a key distinction that does not apply to labour or overhead.
For labour and variable overhead, rate (price) variances and efficiency (quantity) variances are both based on actual hours worked, so they do sum neatly to the spending variance.
Labour rate variance = (Actual hours x Actual rate) - (Actual hours x Standard rate). Unfavourable if the actual wage rate exceeded the standard.
Labour efficiency variance = (Actual hours x Standard rate) - (Standard hours allowed x Standard rate). Unfavourable if more hours were worked than the standard allowed.
Variable overhead follows the same structure as labour, using the same activity base (typically direct labour hours):
Variable overhead rate variance = (Actual hours x Actual rate) - (Actual hours x Standard rate).
Variable overhead efficiency variance = (Actual hours x Standard rate) - (Standard hours allowed x Standard rate).
Standard cost per unit = Standard quantity per unit x Standard price per unit
Standard quantity allowed (SQ) = Actual output x Standard quantity per unit
Price variance = (AQ x AP) - (AQ x SP) = AQ x (AP - SP)
Quantity variance = (AQ x SP) - (SQ x SP) = SP x (AQ - SQ)
Spending variance = (AQ x AP) - (SQ x SP) = Price variance + Quantity variance (exact for labour and overhead; approximate for materials when purchases differ from usage)
Where:
AQ = Actual quantity of input
AP = Actual price per unit of input
SP = Standard price per unit of input
SQ = Standard quantity allowed for actual output
Standard costing is widely used in manufacturing. A car manufacturer, for instance, has a standard cost card for every component: the amount of steel per body panel, the labour hours per assembly step, the overhead per machine hour. Monthly variance reports tell plant managers whether material waste is creeping up or whether a new supplier's lower price is offsetting a quality issue.
Service businesses adapt the same logic. A consulting firm might set a standard number of hours per engagement type and a standard billing or cost rate per hour, then track rate variances (senior staff doing junior work) and efficiency variances (projects running over the budgeted hours).
Students often assume that materials price variance + materials quantity variance = materials spending variance. This is only true when the quantity purchased equals the quantity used. When they differ (inventory builds or draws down), the two sub-variances will not sum to the spending variance.
Students sometimes confuse which quantity to use. The price variance uses the quantity purchased; the quantity variance uses the quantity used. Mixing these up produces wrong answers.
A favourable price variance for materials might mean the purchasing department found a cheaper supplier, but it could also mean they bought lower-quality material, which may cause an unfavourable quantity variance (more waste) downstream.
"Standard" does not mean "ideal." Standards should be tight but attainable under normal operating conditions, including a reasonable allowance for waste and downtime.
The three-column model (AQ x AP, AQ x SP, SQ x SP) is the backbone of standard cost variance problems. Know it cold.
Expect questions that give you actual and standard data and ask you to compute price and quantity variances for materials, labour, or overhead, label each F or U, and interpret the result.
The materials purchased-vs.-used distinction is a favourite exam trap. Read the problem carefully to see whether you are given units purchased, units used, or both.
Be prepared to explain what might cause a specific variance (e.g. "What could explain a favourable materials price variance combined with an unfavourable materials quantity variance?").
Know that for labour and overhead, rate + efficiency = spending variance, but for materials this may not hold.
True or False: The standard quantity allowed is calculated by multiplying actual output by the standard quantity per unit. (True)
Fill in the blank: Price variance = AQ x (______ - ______). (AP - SP)
True or False: For direct materials, the price variance is always based on the quantity used in production. (False, it is based on the quantity purchased.)
Fill in the blank: Labour rate variance + labour efficiency variance = labour ______ variance. (spending)
True or False: Standards should represent ideal, perfect-world performance with zero waste. (False, they should be tight but attainable, with an allowance for normal inefficiencies.)
Q: A company produced 1,000 units. The standard allows 3 kg of material per unit at $2/kg. Actual usage was 3,200 kg at $1.90/kg. Calculate the materials price variance and quantity variance.
A: SQ = 1,000 x 3 = 3,000 kg. Price variance = 3,200 x ($1.90 - $2.00) = 3,200 x (-$0.10) = -$320 = $320 F. Quantity variance = $2.00 x (3,200 - 3,000) = $2.00 x 200 = $400 U.
Q: Using the same data, what is the materials spending variance?
A: Spending variance = (3,200 x $1.90) - (3,000 x $2.00) = $6,080 - $6,000 = $80 U. Note: $320 F + $400 U = $80 U. In this case the two sub-variances do sum to the spending variance because units purchased = units used.
Q: A company's standard allows 2 direct labour hours per unit at $15/hour. It produced 500 units and used 1,050 hours at $15.40/hour. Calculate the labour rate and efficiency variances.
A: Standard hours allowed = 500 x 2 = 1,000 hours. Rate variance = 1,050 x ($15.40 - $15.00) = 1,050 x $0.40 = $420 U. Efficiency variance = $15.00 x (1,050 - 1,000) = $15.00 x 50 = $750 U.
Q: Why might the materials price variance and quantity variance for a period not sum to the materials spending variance?
A: Because the price variance is based on the quantity purchased while the quantity variance is based on the quantity used. When a company purchases more material than it uses (or vice versa), the two variances cover different quantities and will not add to the total spending variance.
Q: A plant manager reports a favourable materials price variance but an unfavourable materials quantity variance. What might explain this combination?
A: The purchasing department may have bought cheaper, lower-quality materials. The lower price produces a favourable price variance, but the inferior quality leads to more waste and rework on the production floor, resulting in an unfavourable quantity variance. This is a classic example of how variances can be interdependent.
This chapter is a direct extension of Chapter 9's flexible budgets. The spending variances from Chapter 9 are decomposed here into their price and quantity components. If Chapter 9 tells you that costs were out of line, Chapter 10 tells you why.
The concept of standard costs also connects to job-order and process costing systems covered earlier in the course, where standards feed into predetermined overhead rates and inventory valuation. In later chapters, fixed overhead volume variances build on the same general model introduced here.
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