Journal of Information Organization P Paramasivaiah 16 3 2026 https://doi.org/10.6025/jio/2026/16/3/122-138 https://www.dline.info/jio/fulltext/v16n3/jiov16n3_2.pdf This study measures and ranks cross country dispersion and inequality in the allocation of compulsory instruction time across curriculum subjects at two levels of education. Drawing on the OECD Education at a Glance database (Instruction Time per Subject by Level of Education), the analysis covers primary education (ISCED 1; N = 347 observations) and lower secondary general education (ISCED 2/24; N = 395 observations) across OECD member and partner countries. Six complementary dispersion and inequality indicators standard deviation, interquartile range, coefficient of variation, Gini coefficient, median absolute deviation, and intercountry range are computed at both the aggregate and subject levels, and synthesised into a composite inequality score via equal weighted percentile ranking. The results reveal three principal findings. First, primary education exhibits substantially greater cross country heterogeneity than lower secondary education on every indicator examined. Second, the dispersion hierarchy is sharply bifurcated: flexible, optional, and vocationally oriented curriculum categories (e.g., Subjects with Flexible Timetable, Options Chosen by Students, Non-compulsory Curriculum) display the highest inequality, whereas core academic subjects Mathematics and Reading, Writing and Literature show the strongest international standardisation. Third, inter-country ranges approaching 100 percentage points for flexible categories reflect fundamentally divergent national philosophies of curriculum design. The findings are interpreted through the ex-ante equality-of-opportunity framework, which treats country of schooling and curriculum category as circumstances beyond individual control, thereby framing instruction time inequality as a structural determinant of educational opportunity. The study contributes a transparent, multi indicator methodology for monitoring curricular convergence and divergence across education systems.