On top of the quoted figure, there is an equivalent of employer's FICA contributions. The rate is around 12.5%. Anyway, this is treated separately and you don't generally hear about it; employers factor it into their calculations before deciding on a salary range.
Exception: it's somewhat common for public sector employees to have the employer's contribution quoted on their payslips, perhaps to make them feel like they're paying into the system.
In my company we pay about 25% on top for social security, worker's benefits, health insurance, etc. This is without any company-provided benefits such as trainings, conference allowances, holidays, etc.
There's the official one which you would declare (pre-tax, or "on-paper"), the actual you get (post-tax, or "hands-on") and the one that shows your actual cost to the employer (pre-tax salary + 31% additional tax).
50%~ overhead sounds about right.