Performance Management · Material mix and yield variances

Interpreting Mix and Yield Variances in ACCA PM

Updated 11 October 2026 · Fact-checked

Mix and yield variances split the material usage variance. Mix shows the cost effect of using a different blend of inputs. Yield shows the effect of more or less output per input. They are linked: a cheaper mix may cut yield or quality. Judge them together, by their net effect.

Understand Interpreting Mix and Yield Variances

A material mix variance tells you what happened because the blend of materials differed from standard. A material yield variance tells you what happened because total input produced more or less output than standard. Together they add up to the material usage variance.

The two are interdependent. Managers can use more of a cheap material and less of an expensive one. That gives a favourable mix variance. But the cheaper blend may produce more waste, lower quality or less output. That shows up as an adverse yield variance. So never judge one without the other.

Causes of an adverse mix variance include: a shortage of the standard material, so a substitute is used; operators using more of the material that is easy to hand; poor scheduling or batch control; a deliberate cost-cutting change; and a standard mix that is unrealistic. Causes of an adverse yield variance include: poor quality or faulty materials, machine problems, untrained or careless labour, spoilage, evaporation, and a mix change that damages output.

A favourable mix variance is not always good news. The question to ask is whether the net effect of mix and yield is favourable, and whether quality, customer satisfaction and brand are affected. Changing the mix is worthwhile only if the saving in material cost per unit of good output is greater than the extra costs, such as lost yield, rework, returns and lost sales.

Also ask who is responsible. Purchasing may cause a mix change by buying cheaper or substitute material. Production may cause yield loss. Some variances are uncontrollable, for example a supplier shortage. The standard itself may also be out of date.

Key rules to remember

Material mix variance: (Actual total input quantity in standard mix − Actual quantity used) × Standard price per unit, for each material; Positive means favourable. Sum across materials for the total. Applies when materials can be substituted.
Material yield variance: (Actual total input − Standard input for actual output) × Standard average cost per unit of input; Equivalent to (Actual output − Standard output from actual input) × Standard cost per unit of output. Adverse when you used more input than standard allowed.
Link to usage variance: Mix variance + Yield variance = Total material usage variance; Use this as a check on your workings. Keep the sign of each variance (F or A).
Is a mix change worthwhile?: Cost per unit of good output = Cost per unit of input mix ÷ Yield from the mix; Compare the old and new mix. Then consider quality and sales effects that are not in the figures.

How to solve Interpreting Mix and Yield Variances questions

Use this method for any question that asks you to calculate and then comment on mix and yield variances.

1Work out the standard mix, standard prices and standard yield (output per unit of input).
2Calculate the actual total input and the standard input for the actual output.
3Calculate the mix variance for each material, then the total. Mark each F or A.
4Calculate the yield variance using the standard average cost per unit of input.
5Check that mix + yield equals the total usage variance. Fix any difference before you comment.
6Interpret each material: say which was over- or under-used and give a likely cause that fits the scenario.
7Link the two variances. Say whether the net effect is favourable and whether a mix change is worthwhile, including quality and sales effects.
8Finish with a recommendation: investigate, change the standard, control the mix, or keep the current mix.

Quickest way: Fast comment routine

When to use it: Use it in Section C when the numbers are given or already calculated and you must write a short comment.

Write the sign and size of mix, yield and total usage first.
Say whether they offset each other. Opposite signs suggest cause and effect.
Give one cause for each from the scenario, such as a substitute material or poor quality input.
State the net cost effect and whether the mix change was worthwhile.
Add one point on quality or customer impact and one action.

Common mistakes in Interpreting Mix and Yield Variances

Commenting on mix alone and calling a favourable mix variance good.
The sign F looks like good news, so students stop thinking.
Fix: Always look at yield and the net usage variance. Ask what the cheaper mix did to output and quality.
Using actual prices instead of standard prices in the calculation.
Students mix up price and usage variances.
Fix: Mix and yield are quantity variances, so use standard prices only.
Writing generic causes such as 'poor management'.
Students memorise a list and do not read the scenario.
Fix: Use details given: a supplier shortage, new staff, a machine fault or a new recipe. Tie each cause to a variance.
Forgetting that mix and yield add to usage.
They are calculated separately and never reconciled.
Fix: Add them and compare with the total usage variance as a check.
Recommending a permanent mix change from the variance figures alone.
Students ignore non-financial effects.
Fix: Compare cost per unit of good output, then mention quality, customer reaction, rework and the reliability of supply.
Treating every variance as controllable.
Students assume someone is always at fault.
Fix: Ask whether the cause was a market shortage or a flawed standard. Say who is responsible and whether the standard needs revising.

Worked examples

Example 1

A product has this standard input per batch: A 60 kg at ₹10 per kg and B 40 kg at ₹25 per kg. 100 kg of input should yield 90 kg of output. Actual output was 4,500 kg. Actual input was A 3,300 kg and B 1,900 kg. Calculate the mix, yield and usage variances and comment.

Show the solution

Standard cost per kg of input = (60 × 10 + 40 × 25) ÷ 100 = 1,600 ÷ 100 = ₹16.
Standard input for 4,500 kg output = 4,500 ÷ 0.9 = 5,000 kg (A 3,000 kg, B 2,000 kg).
Actual total input = 3,300 + 1,900 = 5,200 kg. Actual input in standard mix = A 3,120 kg, B 2,080 kg.
Mix A: (3,120 − 3,300) × 10 = ₹1,800 adverse. Mix B: (2,080 − 1,900) × 25 = ₹4,500 favourable. Total mix = ₹2,700 favourable.
Yield: (5,200 − 5,000) × 16 = ₹3,200 adverse.
Check usage: A (3,000 − 3,300) × 10 = ₹3,000 A; B (2,000 − 1,900) × 25 = ₹2,500 F; net ₹500 A. Mix ₹2,700 F − yield ₹3,200 A = ₹500 A. It agrees.
Comment: more of cheap material A and less of dear material B gave a mix saving. But input was 200 kg more than standard, so yield was poor. The yield loss is bigger than the mix saving.

Answer: Mix ₹2,700 favourable; yield ₹3,200 adverse; total usage ₹500 adverse. The cheaper mix probably reduced yield, and the net effect was adverse, so the change was not worthwhile on material cost alone.

Example 2

Using the standard in the previous example, management considers a new mix of 70 kg A and 30 kg B per 100 kg input. It expects yield to fall to 88 kg of output. Is the change worthwhile on material cost? Comment on other factors.

Show the solution

Standard cost per 100 kg input = ₹1,600. Cost per kg of output = 1,600 ÷ 90 = ₹17.78.
New cost per 100 kg input = 70 × 10 + 30 × 25 = 700 + 750 = ₹1,450.
New cost per kg of output = 1,450 ÷ 88 = ₹16.48.
Saving = 17.78 − 16.48 = about ₹1.30 per kg of output. On 4,500 kg this is about ₹5,850.
Non-financial points: quality may fall, so returns or complaints may rise. The yield forecast is uncertain, and a small further fall in yield could remove the saving. Material B supply and customer specification should also be checked.

Answer: Yes, on cost alone: about ₹16.48 against ₹17.78 per kg of output, a saving of about ₹1.30 per kg. It is worthwhile only if quality is acceptable and the yield forecast holds.

Exam tips

Show every calculation and mark F or A. In Section C you can earn marks for method even if a figure is wrong.
In written parts, tie comments to the scenario. Generic lists score poorly.
Always discuss mix and yield together and give the net effect.
Mention quality, customers and whether the standard is realistic when you judge a mix change.
In objective tests, remember mix + yield = usage. This lets you check a variance quickly.

Practice questions from Material mix and yield variances

Interpreting Mix and Yield Variances: frequently asked questions

Are mix and yield variances related?

Yes. Together they make up the total material usage variance. They are often linked in cause too: a change to a cheaper mix can lower yield. So read them together.

What causes an adverse material mix variance?

Common causes are a shortage of the standard material, so a substitute is used, poor scheduling, operators not following the recipe, and a standard mix that is out of date. It is adverse when the actual blend costs more than the standard blend.

Can a favourable mix variance be bad?

Yes. If the cheaper blend lowers output or quality, the yield variance may be adverse and larger. Judge the net effect and the impact on customers.

How do I comment on mix and yield variances in the exam?

State each variance with its sign, give a cause from the scenario, link the two, say who is responsible and give a recommendation. Keep it short and specific.