Postal Code finder uses the current location from your browser to determine the postal code. So allow location access in the browser when prompted to get the most accurate current location details of yours. This tool will also show the location and other known details about your current location.
Visit this link from your mobile may help you to find more accurate data. If you are sure about the location and need to find the postal code. Use the postal code map service instead.
Scan this QR code to access this web page from the mobile browser.