  The robust estimation of entanglement is key to the validation of
implementations of quantum systems. On the one hand, the evaluation of standard
entanglement measures, either using quantum tomography or using quantitative
entanglement witnesses requires perfect implementation of measurements. On the
other hand, measurement-device-independent entanglement witnesses (MDIEWs) can
certify entanglement of all entangled states using untrusted measurement
devices. We show that MDIEWs can be used as well to quantify entanglement
according to standard entanglement measures, and present a practical method to
derive such witnesses using experimental data only.
