Glossary · Lifestyle and budget

Equivalence scale

A multiplier system (commonly OECD-modified: 1.0 / 1.5 / 1.85 / 2.2) that scales single-person costs to household-level costs.

An equivalence scale answers the question: if a single person needs €X, what does a couple, or a family of three, need? The OECD-modified equivalence scale — the international standard — uses 1.0 for the first adult, +0.5 for each additional adult, and +0.3 for each child under 14. So a family of two adults plus a child sits at 1.8× the single-person baseline.

The reason multipliers aren't simply additive is that housing, utilities, and many durable goods are shared. A two-bedroom apartment doesn't cost twice as much as a one-bedroom; running a heating bill for two people isn't double what one person pays. Per-person variable costs (food, healthcare, transport) scale closer to linearly.

Mundevo's cost-of-living and salary-needed pages use a slightly adapted scale (1.0 / 1.5 / 1.85 / 2.2 for sizes 1, 2, 3, 4+). The differences from pure OECD are small and reflect that very large families share less efficiently per extra person.

Formula

OECD-modified scale:
  household_factor = 1.0 + 0.5 × (extra_adults) + 0.3 × (children_under_14)

Where Mundevo uses this

Calculator — /calculator

Related terms

Lifestyle tier

Mundevo's four-step scale (frugal / balanced / comfortable / premium) for how much you spend relative to the median resident.

Cost-of-living index

A single number that scores how expensive a city is, normalized so New York City = 100.

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