ACCA PM December 2026: Mix and Yield Variances – Why Your Mix Variance Is Probably Wrong

Your mix variance is not "actual kg minus standard kg for the output achieved." That is a usage variance, and PM markers will not give you the marks for it. Mix is measured on total actual input, at the standard mix, and yield is whatever is left.

Where the marks go in PM

The PM study guide asks you to calculate and interpret material mix and yield variances, and it expects you to explain them, not just compute them. Mix tells you whether the blend of inputs was cheaper or dearer than the standard blend. Yield tells you whether the total input produced as much output as it should have. Together they make up the total material usage variance.

The classic slip is to compare each material's actual quantity with the standard quantity for actual output. That gives you a usage variance per material. It blends mix and yield together, so it cannot be your mix answer.

The second slip is the yield price. Yield is valued at the standard cost per kg of output (or per kg of input, depending on how you frame it), not at the price of one material. Pick one consistent method and show it.

Worked example

Standard mix per 100 kg of input: 60 kg A at £5 (£300) and 40 kg B at £10 (£400), total £700. Standard loss is 10%, so 100 kg of input gives 90 kg of output. Standard cost per kg of output is £700 / 90 = £7.78.

Actual: 500 kg of A and 500 kg of B (1,000 kg in total), producing 850 kg of output.

Wrong answer: standard quantity of A for 850 kg of output is 850 / 0.9 x 0.6 = 566.7 kg. Actual 500 kg gives (566.7 - 500) x £5 = £333 F. That is a usage variance for A, not a mix variance.

Right answer:

Mix. Take the actual 1,000 kg input and split it in the standard 60:40 ratio: A 600 kg, B 400 kg. A: (600 - 500) x £5 = £500 F. B: (400 - 500) x £10 = £1,000 A. Total mix variance = £500 A. You used more of the expensive material than the standard blend allows.

Yield. Standard output from 1,000 kg of input is 900 kg. Actual output is 850 kg, so you are 50 kg short. 50 x £7.78 = £389 A.

Check. Actual input at standard prices is (500 x £5) + (500 x £10) = £7,500. Standard cost of actual output is 850 x £7.78 = £6,611. The difference is £889 A, and £500 + £389 = £889. If your two numbers do not add to the usage total, something is wrong. This check takes 30 seconds and is worth doing every time.

What to do

1. Always set out the three lines first. Actual input in actual mix, actual input in standard mix, standard input for actual output. Mix is the gap between lines one and two. Yield is the gap between lines two and three.

2. Prove it adds up. Mix plus yield must equal total usage. Write the check on your answer. It shows the marker you know the link, and it catches errors before they cost you.

3. Interpret in one sentence each. "Adverse mix: more of the dearer material B was used. Adverse yield: output was 5.6% below standard, which may point to poor quality inputs or process waste." Then say whether the mix could be changed without hurting quality. That is the bit that earns the application marks.

The bottom line

Variance questions are among the most predictable marks in PM, and mix and yield is where many candidates lose them through one wrong comparison. Get the three-line layout locked in and the rest is arithmetic.

Mix is about the blend. Yield is about the output. Never confuse the two.