React Native webview get Height

const script = `<script>window.location.hash = 1;document.title = document.getElementsByTagName('html')[0].scrollHeight;</script>`;
 onNavigationStateChange(navState) {
    Util.log("webView Height:", navState.title);
    this.setState({
      height: navState.title
    });
  }

  renderMobileBody(){
    return(

      <WebView
        automaticallyAdjustContentInsets={false}
        style={[styles.webView, {height: Number(this.state.height)}]}
        source={{html: this.htmls + script}}
        onNavigationStateChange={this.onNavigationStateChange.bind(this)}
        javaScriptEnabled={true}
        domStorageEnabled={true}
        scalesPageToFit={true}
        decelerationRate="normal"
        javaScriptEnabledAndroid={true}
        />
    );
  }

it's work.
I can take html height.
But how to calculate px height to dp?