UMS, raw marks and what the examiner actually records
Every A-Level paper is marked in raw marks — the numbers written on the script, out of whatever the paper is worth. Those raw marks are then converted into UMS (Uniform Mark Scale), a fixed currency in which every unit of every subject is worth the same number of marks no matter how hard the paper turned out to be. A brutal further-maths paper that everyone found impossible can be converted upward; a paper that turned out easy is converted down. The grade boundaries are set after the papers are marked, and they are what the conversion is built from.
This is why the UMS for a paper is not simply raw ÷ maximum × UMS maximum. The real conversion is piecewise linear: between two adjacent grade boundaries, raw marks map to UMS along a straight line; the slope changes at every boundary. If an A is 64 raw marks and 80 UMS while a B is 56 raw and 70 UMS, then 62 raw marks sits halfway between the two boundaries and converts to 75 UMS — not to 77.5, which is what scaling by the maximums would give.
Enter your board's published raw boundaries into the table above and the conversion becomes exact for your series; leave them alone and the tool falls back to a straight proportional map, which is a reasonable approximation and exactly right when the boundaries happen to be evenly spread.
The standard UMS bands
Across UK A-Levels the UMS percentages are uniform, and the ten-point spacing is deliberate — each grade is a ten-point band:
| Grade | UMS | What it means |
|---|---|---|
| A* | 90% and above | Plus the second condition below |
| A | 80–89.9% | Strong performance |
| B | 70–79.9% | Comfortably above the pass line |
| C | 60–69.9% | The usual university entry requirement |
| D | 50–59.9% | A pass |
| E | 40–49.9% | The minimum pass |
| U | Below 40% | Ungraded |
On a 300-mark A-level, each ten-point UMS band is 30 marks wide: A* from 270 UMS, A from 240, B from 210, C from 180, D from 150, E from 120. Internationally the same percentages drive most A-Level and International A-Level grades, which is why 80% is such a common target.
The A* rule is two conditions, not one
An A* is not simply "90%". In the modular specifications it requires at least 80% overall and around 90% in the A2 units. A student with 82% overall who scored 95% in the A2 units gets the A*; a student with the same 82% who scored 78% in the A2 years does not, even though the aggregate is identical. That is why the percentage-to-grade tab asks for the A2-stage percentage separately: the tool tells you whether the second condition is satisfied instead of quietly handing out an A*. Some boards and international specifications award A* on a single aggregate cut-off, so check your specification — but the two-part rule is the safe assumption in the UK.
AS + A2: which weighting applies to you?
This is where the tool earns its place, because the answer changed with the 2015 reforms in England:
- England, reformed A-Levels: linear. Everything is examined at the end of two years and the AS is a separate, decoupled qualification that does not count towards the A-Level at all. Set the AS weight to 0 and the tool simply grades the A2 aggregate.
- Wales (WJEC) and Northern Ireland (CCEA): the AS still counts for 40% of the A-Level, with the A2 contributing 60%.
- Legacy modular A-Levels and staged Cambridge International routes: the AS is normally 50% of the total (200 UMS of 400).
The combined percentage is a weighted average of each stage's own percentage: AS% × 0.4 + A2% × 0.6 for the 40/60 case. With AS at 160 of 200 (80%) and A2 at 231 of 300 (77%), that gives 80 × 0.4 + 77 × 0.6 = 78.2%, a B — and the results table shows exactly what the A2 has to score to pull each grade back into range. Note the asymmetry: the A2 carries the larger share, so a weak second year cannot be rescued by a brilliant first year.
Reading the numbers in the right order
- Raw marks first. They are what the examiner awarded and the only thing you can verify on a returned script.
- Then UMS, using the boundaries for your series, because UMS is what the grade is calculated from.
- Then the grade. Never compare raw percentages from two different papers and assume the harder one hurt you — converting to UMS is precisely the mechanism that protects you from that.
Frequently asked questions
What is UMS in A-Levels?
UMS stands for Uniform Mark Scale. Raw marks from each paper are converted to UMS so that a unit is always worth the same number of marks whichever series you sat it in — a hard paper is scaled up, an easy one down. Grade boundaries are decided after marking and the conversion is built from them.
How do I convert raw marks to UMS?
Use the boundaries for your series: between two adjacent boundaries the conversion is a straight line. If A is 64 raw = 80 UMS and B is 56 raw = 70 UMS, then 62 raw is halfway and becomes 75 UMS. Scaling by the maximums (62 ÷ 80 × 100 = 77.5) is only correct when the boundaries happen to be proportional.
What percentage do I need for an A* at A-Level?
The aggregate cut-off is 90% of the UMS, but that is only half the rule: most modular specifications also require at least 80% overall and about 90% in the A2 units. A high aggregate with an average second year is graded A, not A*.
Does AS count towards the A-Level?
It depends on the specification. England’s reformed A-Levels are linear and the decoupled AS does not count at all. In Wales and Northern Ireland the AS contributes 40%, and the legacy modular specs and staged Cambridge International routes normally use 50/50.
How do I work out my A-Level grade from AS and A2 scores?
Turn each stage into a percentage of its own maximum, then take the weighted average: with a 40/60 split, AS 160/200 (80%) plus A2 231/300 (77%) gives 0.4 × 80 + 0.6 × 77 = 78.2%, a B. The tool also shows what the A2 has to score for each higher grade.
What percentage is a grade C at A-Level?
60% of the UMS — 180 out of 300 on a full A-Level. The bands are evenly spaced at ten points: A* 90, A 80, B 70, C 60, D 50, E 40, with anything below 40% ungraded (U).
Are these the official grade boundaries?
No. The UMS percentages are standard, but the raw marks behind them are published separately for each subject and each exam series, and they move from year to year. Enter your board’s published raw boundaries into the table to get an exact conversion — until then the tool assumes proportional boundaries.