Use the speed the authority considered (for radar, after the technical margin) and the limit in force at the spot: the general one (50 km/h in localities, 90 on roads, 120 on motorways for a car) or the signposted one, if lower.

Serious offence (article 145.º of the Código da Estrada): besides the fine, you lose 2 licence points and risk a driving ban of 1 month to 1 year. Paying the minimum fine (€120) does not stop the ban: the case continues just to decide it (article 172.º, n.º 4). With no serious or very serious offences and no road crimes in the last 5 years, the ban's execution can be suspended (article 141.º).

The calculator applies the article 27.º, n.º 2 table of the Código da Estrada to general and signposted limits. Out of scope: the special limits the law sets for certain drivers and vehicles, coexistence zones, repeat offences and driving too fast for the conditions (article 24.º), which is a different offence. The exact fine within the range is set in the proceedings.

Educational estimate, not legal or financial advice. The decision belongs to ANSR or the court; official values: Código da Estrada and the Portal das Contraordenações.