Client error: (413) Request Entity Too Large

I am trying to post a graph on my plotly(free subscription account) and i am getting th4e following error
Error: Client error: (413) Request Entity Too Large
This file is too big! Your current subscription is limited to 524 KB uploads. For more information, please visit: https://plot.ly/settings/subscription.

I ve posted several other charts on my free account, but this is the first time i am getting this error, i cannot find any chart size limit on subscription page, Can anyone please help, directing me towards some right direction to resolve this?

Thanks