The following three variables are relevant for calculating the approximation to the nationwide natural threshold: M (average district magnitude), S (total assembly size), and E (number of electoral districts). The formula is this: T = 75% / ((M + 1) * √E) or, which is the same, T = 75% / (((S/E) + 1) * √E), or 75% / (((S + E)/E) * √E).35 To illustrate with our examples of Spain and Ireland: in Spain, where S=350, and E=52, the nation-wide natural threshold (T) is 1.35%, while in Ireland, where S=165 and E=42, T amounts to 1.85%.36 The following are some additional calculations of the nationwide natural threshold (source: Gallagher and Mitchell, footnote 27, Taagepera, footnote 31):

Nation-wide Natural Threshold in Majority/Plurality Systems

Country Nation-wide Natural Threshold
France 1.56%
UK 1.48%

Nation-wide Natural Threshold in Combined Systems

Country Nation-wide Natural Threshold
Germany 0.13%
Hungary 1.77%
Russia (when the combined system was applied) 1.67%

Nation-wide Natural Threshold in Proportional Systems

Country Nation-wide Natural Threshold
Austria 0.41%
Belgium 1.93%
Denmark 0.43%
Finland 1.32%
Ireland 2.34%
Italy 1.48%
Netherlands 0.5%
Spain 1.35%