Angular UI-Grid: How to get number of total items after filtering

You should avoid jQuery (as another post suggests) and interact with the API instead.

You first need to save a reference to the API on the grids creation event.

$scope.gridOptions = {
    ....
    onRegisterApi: registerGridApi,
    ....
};
function registerGridApi(gridApi) {
    $scope.gridApi = gridApi;
}

You should already know the total number of rows.

You can get the number of visible/filtered rows with:

gridApi.core.getVisibleRows().length

or

gridApi.grid.getVisibleRows().length

You can get the number of selected rows with:

gridApi.selection.getSelectedRows().length