Spain's classroom ratio cut will cost €28 billion over a decade but won't improve learning, study finds
A government plan to reduce the maximum number of students per classroom in Spain will require at least €28.18 billion in net public spending over ten years, yet scientific evidence suggests it will yield negligible improvements in academic performance.
A legislative initiative by Spain's Ministry of Education to lower mandatory student-to-teacher ratios faces sharp criticism from a new economic analysis, which projects a net cost of over €28 billion across the next decade with little to no impact on learning outcomes.
The proposed reform
Currently under debate in the Congress of Deputies, the bill would reduce the maximum number of students per class in primary education from 25 to 22, and in compulsory secondary education (ESO) from 30 to 25. Additionally, each student with special educational needs would count as two for the purposes of the ratio. The reform is scheduled for progressive implementation, reaching full deployment by 2031.
The price tag
A study by the Esade Centre for Economic Policy (EsadeEcPol), authored by researchers Lucas Gortazar and José Montalbán, estimates the net average annual budgetary cost at €2.818 billion between 2027 and 2036, accumulating to €28.184 billion. In the peak year of 2031, when the law is fully in force across both primary and secondary stages, the real cost will hit €6.549 billion, offset by a demographic dividend of €1.38 billion from declining student numbers, leaving a net peak cost of €5.169 billion. The reform would require creating approximately 69,000 new classrooms and hiring the equivalent of 103,000 full-time teachers.
The economic memorandum of the bill says that lowering ratios will not entail costs, but they have not made public any data to support that. We have done the math and, making a conservative estimate, we do see an effect.
Unequal distribution of funds
The report highlights a regressive distribution of resources. Schools serving the wealthiest 25% of students would absorb 31.2% of the funding, while those serving the most vulnerable 25% would receive only 21.9%. This is because the linear cut benefits schools with currently fuller classrooms, which are concentrated in higher-income urban areas. Regionally, Andalusia, Catalonia, and Madrid would concentrate 63% of the national cost, despite enrolling roughly 50% of all primary and secondary students.
- Progressive implementation of new ratios begins in primary and secondary schools.
- Reform fully deployed. Real cost peaks at €6.549 billion; net cost at €5.169 billion after demographic savings.
- End of the first decade of implementation. Accumulated net cost reaches €28.184 billion.
Questionable educational impact
Despite its high cost, the policy lacks scientific backing. The EsadeEcPol analysis, drawing on data from the Ministry, the National Statistics Institute (INE), and international assessments like PISA, TIMSS, and PIRLS, concludes that reducing class sizes generates little to no advantage in student performance. The researchers argue the funds could be more effectively deployed on targeted interventions such as intensive tutoring programs or salary supplements for teachers in high-complexity schools.
The investment effort of this law is very high, and the consequences for learning are scarce.
A call for targeted alternatives
Rather than a universal reduction, EsadeEcPol advocates applying the measure only in high-complexity schools where students face socioeconomically disadvantaged conditions. The study also recommends generalizing other initiatives with a stronger evidence base for improving learning, such as small-group tutoring during school hours.
