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Z-Score / District Rank Estimator

Estimate your A/L Z-score, percentile and district rank from your marks using the standard Z = (mark − mean) ÷ SD formula.

Estimate, then plan

Everything runs in your browser. You supply the statistics — the tool does the arithmetic.

This is an estimate for planning only — not an official UGC/NIC result. An official Sri Lankan A/L Z-score is computed by the Department of Examinations from the island-wide distribution of marks for each subject and year, across all candidates. It cannot be reproduced from one student's marks. Any reference values you type here are your own assumptions, and results will only be as good as those assumptions.

How the estimate works

For each subject the tool applies the standard score formula used for standardised marks:

Z = (your mark − subject mean) ÷ subject SD

  • Z = 0 means you scored exactly the subject average.
  • Z = +1 means one standard deviation above the average (roughly the top ~16%).
  • Z = +2 is roughly the top ~2.3%.
  • The aggregate estimate averages your subject Z-scores, matching the way an A/L aggregate is built from equally weighted subjects.

The defaults (mean 50, SD 10) are placeholders. Replace them with the real subject statistics for your year if you have them.

1 · Your subjects

Subject Your mark Mean SD Z

Estimated Z-scores

Aggregate Z (avg)
—
Estimated band
—
Approx. percentile
—
if the distribution is normal

Per-subject Z averages are a simplification — the real aggregate also depends on how subject marks are combined and on the island-wide cohort. Treat this as a planning signal, not a prediction of your results.

2 · District rank estimator

Position a candidate within a district cohort you define. The rank assumes the district Z-scores are normally distributed around the district mean.

Estimated district position

—

Percentile
—
candidates below you
Approx. district rank
—
—
Top
—
of the cohort

Where to get real reference data

Use your own released statistics or published summaries for the year you sat: subject means and standard deviations, cut-off Z-scores and district candidate counts. This tool deliberately does not ship guessed cut-off tables — you enter the reference data, so you always know its source.