Software | EC8 Spectrum Calculator Web App

An online tool to calculate acceleration and displacement response spectrum according to EC8 (EN 1998-1) European Standard. Fill out the form with the desired parameters, and click Calculate button to generate the response spectra. You can download the plots in PNG and PDF formats, as well as to export the values in XLS and CSV files by clicking on icon. Zoom in/out functionality is also available.


The reference peak ground acceleration (PGA) on type A ground, agR, for use in a country or parts of the country, may be derived from zonation maps found in its National Annex.

According to EN1998-1 §3.2.1(3), §2.1(4). For ordinary buildings, an importance factor of γ = 1.0 is recommended.


For elastic analysis of reinforced concrete buildings the value of ξ = 5% can be used. For special cases a viscous damping ratio different from 5% is to be used, this value is given in the relevant Part of EN 1998.

The value to be ascribed to β for use in a country can be found in its National Annex. The recommended value for β is 0.2.

Unless special studies based on the available information indicate otherwise, the design ground displacement dg, corresponding to the design ground acceleration, may be estimated by means of the following expression:

dg = 0.025 ag S TC TD = m.