score:8
I am an ex-India Post employee and we used to advise postage of Rs. 12 for International Post Cards, i.e. India to anywhere. I know few colleagues who encouraged stamps worth Rs. 15. Surface PostCard cost Rs. 4 to 7 while Airmail PostCard cost Rs. 12, except Pakistan, Bangladesh, Nepal and Bhutan which cost Rs. 8.
Hope this helps!
Upvote:3
Indian Post Website has a postage calculator which will show you the cost. Anyway most Post offices websites have this calculator feature.