Five nights in Phnom Penh in Cambodia cost the same as one night in Rio de Janeiro, revealed Hotels.com.
Vietnam and Thailand are also good-value destinations for those on gap year breaks, said Hotels.com, which compared hotel prices around the world during the first half of 2013 with those in the same period last year.
The average price of a hotel room in Phnom Penh in January-June 2013 was just £35 compared with as much as £180 in Rio and £137 in Sydney.
Hanoi in Vietnam (£41), Chiang Mai in Thailand (£44) and Siem Reap in Cambodia (£45) were also among the best-value backpacker destinations during the first half of this year.
Overall, the Asia region saw a 2% drop in average hotel prices in the first six months of 2013.
Kate Hopcraft, of Hotels.com, said: "It's no surprise that South East Asia is the most cost-effective destination on the backpacker route but this latest drop in prices has come at a welcome time for those setting off on their gap year trip of a lifetime. "
1. Phnom Penh, Cambodia £35
2. Hanoi, Vietnam £41
3. Chiang Mai, Thailand £44
4. Siem Reap, Cambodia £45
5. Pattaya, Thailand £49
6. Ho Chi Minh City, Vietnam £60
7. Bangkok, Thailand £63
8. Goa, India £68
9. Krabi, Thailand £77
10. Phuket, Thailand £78