If you need a way to convert Chinese characters into Pinyin with tone marks then look no further than Google translate.
Just enter Chinese text into the box on the left then click on the Ä (capital A with an umlaut) in the bottom right corner and the Pinyin with tone marks will be displayed below.
If you find that Chinese is incorrectly auto-detected as Japanese, just manually select Chinese from the drop-down selection of languages.
Thanks to Daan for providing this tip.
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