About 1 in 10 men in some parts of Asia has admitted raping a woman who was not their partner, according to the first large studies of rape and sexual violence.
When their wife or girlfriend was included, that figure rose to about a quarter, the same study showed.
"It's clear violence against women is far more widespread in the general population than we thought," said Rachel Jewkes of South Africa's Medical Research Council, who led study.
The research was paid for by several United Nations agencies and Australia, Britain, Norway and Sweden. The papers were published online on Tuesday in the journal, Lancet Global Health.
In the new research, male interviewers surveyed more than 10,000 men in Bangladesh, China, Cambodia, Indonesia, Sri Lanka and Papa New Guinea.
The word "rape" was not used in the questions, but the men were asked if they had ever forced a woman to have sex when she wasn't willing or if they had ever forced sex on someone who was too drunk or drugged to consent.
In most places, scientists concluded between 6 to 8 percent of men raped a woman who wasn't their partner. When they included wives and girlfriends, the figures were mostly between 30 to 57 percent.
'Wanted to have fun'
The lowest rates were in Bangladesh and Indonesia and the highest were in Papa New Guinea. Previous studies of rape have been done in South Africa, where nearly 40 percent of men are believed to have raped a woman.
Of those who acknowledged forcing a woman to have sex, more than 70 percent of men said it was because of "sexual entitlement."
Nearly 60 percent said they were bored or wanted to have fun while about 40 percent said it was because they were angry or wanted to punish the woman.
Only about half of the men said they felt guilty and 23 percent had been imprisoned for a rape.
A previous report from the World Health Organisation found one-third of women worldwide say they have been victims of domestic or sexual violence.