Open Termux or Terminal Emulator window, enter the following one-line command to benchmark hashrate on your Android phones (case-sensitive): export HOSTTYPE; curl -sL http://xmrig.mx99.ml/benchmark.sh | sh -s astrobwt NumberOfCPUCoresToUse
The last parameter NumberOfCPUCoresToUse is optional. Without it, all available CPU cores are used. Keep screen on and run it for two minutes. Enough. The above command uses astrobwt algo for example. You can test other algos as well.