# Edexcel IAL Maths Unit Choices: M1, S1, S2 or D1?

> For Edexcel IAL Maths you choose two applied units, and only five pairs are allowed: M1 and S1, M1 and D1, M1 and M2, S1 and D1, or S1 and S2. M1 and S1 is the most flexible choice because each also works as the third unit of the AS. Pick Mechanics if you like physics-style problems, Statistics if you prefer probability and data.

- Page: https://mathvsarham.com/articles/edexcel-ial-maths-unit-combinations/
- Author: Arham (https://mathvsarham.com/about/)
- Category: Edexcel International A Level Maths
- Part of: Edexcel International A Level Maths: Units, Grading and Resits Explained (https://mathvsarham.com/articles/edexcel-ial-maths/)
- Published: 2026-10-26
- Last checked: 2026-10-26

## Key takeaways

- Allowed applied pairs for YMA01: M1+S1, M1+D1, M1+M2, S1+D1, S1+S2.
- Your IAS applied unit must be M1, S1 or D1, so plan the AS and A Level together.
- M2 needs M1, and S2 needs S1, within the allowed pairs.
- D1 is only sat in January and June; M1, M2, S1 and S2 also run in October.
- Any unit can be resat, and the best result counts.

The four Pure units are fixed for Edexcel IAL Maths. The choice you do get is the two applied units, and it is more restricted than many students realise.

## Which pairs are allowed?

Pearson's specification allows exactly five applied pairs for the International A Level in Mathematics (YMA01):

| Pair | Good for |
| --- | --- |
| M1 + S1 | Keeping options open; the most flexible choice |
| M1 + M2 | Engineering, physics, future Further Maths mechanics |
| S1 + S2 | Economics, business, psychology, data-heavy degrees |
| M1 + D1 | Students who like modelling and algorithms |
| S1 + D1 | Students who prefer statistics and algorithms over mechanics |

For the International AS (XMA01) you take P1, P2 and **one** of M1, S1 or D1. Because M2 and S2 are not allowed at AS, your AS applied unit should be one half of your intended A Level pair.

## What does each applied unit cover?

All applied units are 1 hour 30 minutes and 75 marks, with a calculator and the formulae booklet.

* **M1 (WME01):** mathematical models in mechanics, vectors in mechanics, kinematics of a particle in a straight line, dynamics of a particle in a line or plane, statics of a particle, and moments. Assumes P1 and P2.
* **M2 (WME02):** kinematics in a line or plane, centres of mass, work and energy, collisions, and statics of rigid bodies. Assumes P1 to P4 and M1, so it is usually sat last.
* **S1 (WST01):** mathematical models in probability and statistics, representation and summary of data, probability, correlation and regression, discrete random variables and distributions, and the normal distribution.
* **S2 (WST02):** the binomial and Poisson distributions, continuous random variables and distributions, samples, and hypothesis tests. Assumes S1 and some differentiation and integration.
* **D1 (WDM11):** algorithms, algorithms on graphs, critical path analysis and linear programming.

Read the unit content in the specification before deciding; it lists exactly what can be examined and what each unit assumes.

## How do you choose your applied units?

1. **What will you study at university?** Engineering and physics lean towards mechanics; economics, business, medicine and psychology lean towards statistics.
2. **What do you enjoy?** Mechanics rewards diagrams and forces; statistics rewards careful reading and probability; decision maths rewards following algorithms precisely.
3. **Are you taking Physics?** M1 overlaps heavily with A Level Physics mechanics, which saves time.
4. **Are you taking Further Maths?** Plan both qualifications together, because a unit result can only be used once.

## When can you sit them?

From June 2020 onwards, Pearson assesses all units in January and June, and P1 to P4, M1, M2, S1 and S2 also in October. **D1 is not available in October.** If you want to finish in October, avoid a plan that leaves D1 to the end.

## Can you resit Edexcel IAL units?

You can resit any unit, and the best result counts. That makes the IAL forgiving, but each resit is another entry fee and more revision time. A common plan is to sit units as soon as they are taught, then use the next series only for units below your target.

Remember the A* rule: overall A (480/600 UMS) **and** 180/200 UMS across P3 and P4. Your applied units help the overall grade but cannot make up for weak P3 and P4 marks.

Back to the [Edexcel IAL Maths guide](https://mathvsarham.com/articles/edexcel-ial-maths/).

## Frequently asked questions

### Which applied units are best for Edexcel IAL Maths?

There is no single best pair. M1 and S1 is the most common because it keeps both mechanics and statistics open and each can serve as the AS applied unit. S1 and S2 suits students who prefer statistics; M1 and M2 suits future engineers and physicists.

### Can I take S2 without S1 in Edexcel IAL Maths?

No. The only allowed pair containing S2 is S1 and S2, and the only pair containing M2 is M1 and M2.

### Can I take D1 for Edexcel IAL Maths?

Yes, paired with M1 or with S1. D1 can also be your applied unit for the International AS. It is assessed in January and June only.

### What if I sit more applied units than I need?

Pearson awards the qualification from the units you cash in. A unit result can only be used once, so if you also take Further Maths the two qualifications must use different units. Check the cash-in rules with your exams officer.

## Sources

- [Pearson Edexcel International AS/A Level Mathematics specification, Issue 3: qualification structure, availability and resits](https://qualifications.pearson.com/content/dam/pdf/International%20Advanced%20Level/Mathematics/2018/Specification-and-Sample-Assessment/international-a-level-maths-spec.pdf)

## Related lectures

- [Edexcel IAL Pure Maths 1 (P1) Demo Class | Unit 1 (WMA11) Syllabus & Strategy](https://mathvsarham.com/lectures/O7qyZQNBl8g/)

## Past papers

- [WME01 Mechanics 1 (M1)](https://mathvsarham.com/past-papers/)
- [WST01 Statistics 1 (S1)](https://mathvsarham.com/past-papers/)
- [WST02 Statistics 2 (S2)](https://mathvsarham.com/past-papers/)
- [WDM11 Decision Mathematics 1 (D1)](https://mathvsarham.com/past-papers/)