PSLE T-Score to AL Score Conversion: Why Direct Mapping Is Not Possible

Parents with children who took the PSLE before 2021 often ask a practical question: what does my older child's T-score of 235 or 250 translate to under the new Achievement Level system? It is a natural question — especially for families comparing siblings or trying to gauge whether a secondary school's historical cut-off point is within reach for a younger child.

The short but important answer is that no formula can reliably convert a T-score to an AL score. The two systems measure fundamentally different things, and any attempt at direct conversion misrepresents what each score actually means.

PSLE T-scores were norm-referenced values derived from a student's position relative to the cohort mean and standard deviation, while AL bands are criterion-referenced grades based solely on absolute raw marks — the two systems use different inputs, different scales, and different underlying information, making direct conversion mathematically impossible.

Why Direct Conversion Does Not Work

A T-score aggregate — say, 238 — is a sum of four subject T-scores, each calculated from the formula: 50 + 10 × (Raw Mark − Cohort Mean) / Standard Deviation. To work backwards from 238 to raw marks, you would need to know the cohort mean and standard deviation for each subject in that specific examination year. That information was never published on result slips or certificates, and MOE has not released it retrospectively.

Even if you had the cohort statistics, the conversion would still be unreliable because the AL bands use fixed mark thresholds that do not correspond to any consistent T-score value. A raw mark of 85 in English always maps to AL2 — but the T-score that an 85 produced varied from year to year depending on paper difficulty and cohort performance. In a year with a very difficult English paper, an 85 might have produced a T-score of 68; in an easier year, the same 85 might have produced 62.

The same raw mark generates the same AL band every time, but a different T-score each time. This is why no lookup table or calculator can bridge the two systems.

What MOE Did Instead: Indicative AL Ranges for Schools

Rather than converting individual scores, MOE took a different approach to help families navigate the transition. Using actual raw-mark data from the final T-score cohorts, MOE modelled what the AL outcomes would have been for students admitted to each secondary school in recent years.

This modelling produced the indicative AL cut-off point ranges that are now published annually for every secondary school. For example, a school whose T-score cut-off was consistently around 245–250 might now show an indicative AL range of 6–9. This range reflects the range of PSLE scores held by students who would have been admitted under the new system had it been in place during those years.

These indicative ranges are updated each year with real posting data from the most recent AL cohort, making them increasingly accurate as more years of AL posting data accumulate. By 2026, several years of live AL posting results inform the ranges, and they have stabilised for most schools.

What Parents Should Use Instead of Conversion

For families comparing across siblings who took the PSLE in different eras, the most useful comparison is not numerical but qualitative. A T-score of 240–250 placed a child roughly in the top third of the cohort — eligible for many popular secondary schools and the Express stream. The AL equivalent in terms of school access is a PSLE score in the range of roughly 8–12, depending on the specific schools being targeted.

More practically, parents should focus on the current indicative AL ranges for secondary schools of interest, not on historical T-score cut-offs. A school that previously had a T-score cut-off of 245 now has an indicative AL range — and that range, not the old T-score number, is what matters for a younger sibling's posting prospects.

MOE's SchoolFinder tool publishes the most recent indicative AL ranges for every secondary school, along with information on school programmes, location, and subject offerings, providing families with the data needed to make realistic school choices.

Summary

No direct conversion exists between the old PSLE T-score and the new AL score because they measure different things using different data. Parents should not rely on T-score-to-AL calculators or comparisons. Instead, use MOE's indicative AL cut-off ranges for secondary schools — derived from modelled and live posting data — as the sole reference point for school planning under the current system.

FAQ

Why can't MOE just publish a T-score to AL conversion table?

Because the T-score depended on cohort mean and standard deviation — values that changed every year and for every subject — there is no fixed mapping from T-score to raw mark, and therefore no fixed mapping from T-score to AL band. A single T-score could correspond to many different raw mark combinations, each producing a different AL outcome. A conversion table would be misleading rather than helpful.

My older child scored 250 in the old PSLE. What is the AL equivalent?

There is no precise equivalent, but in terms of secondary school access, a T-score of 250 typically placed a student in the top 15–20% of the cohort, eligible for most popular secondary schools and IP programmes. Under AL, the comparable range for similar school access is roughly AL 6–9, depending on the specific school. For any particular school, check its current indicative AL range rather than trying to convert the old score.

Will the indicative AL ranges keep changing every year?

Indicative ranges are updated annually with the latest posting exercise data. As more cohorts complete the posting process under the AL system, the ranges become more stable. Most schools' ranges have already settled within a narrow band, though high-demand schools at competitive score boundaries may see occasional one-point adjustments.

Can I use sibling priority if one child's T-score is "equivalent" to the younger child's AL score?

Sibling priority in secondary school admission — where it exists at specific schools — is typically based on having a sibling currently enrolled, not on score comparisons. Check individual school admission policies, but do not expect T-score-to-AL comparisons to carry any weight in the posting process, as MOE does not recognise such conversions.