The promise - ahead of vote in Karnataka on Saturday - follows the release of Bollywood's first film on menstrual hygiene in February and similar pledges by political parties in other recent elections.
"They probably thought that like the movie, this is another agenda item that will be popular and will woo the common public," Sulagana Chattopadhyay, a voter, told the Thomson Reuters Foundation by phone from Bengauru.
"Without clear plans on infrastructure and implementation, I'm sceptical and feel it's an election gimmick. But even if 10 percent benefit, then that will be great."
Women in the country face many challenges when they have their periods, especially in rural areas where a lack of awareness and affordability mean many end up using unsanitised cloth or rags, and increase the risk of infections and disease.
The movie "Padman" - which depicts one of Hindi cinema's most popular action heroes, Akshay Kumar, wearing a sanitary pad - has generated debate over the subject.
The ruling Bharatiya Janata Party (BJP) has vowed to give free sanitary pads to students and the poor, and to fix the price at 1 rupee for all women if voted to power.
The Congress party - which governs the state - has promised free pads to students in government colleges and to scrap the current tax on them.
Surbhi Singh, founder of Sachhi Saheli, a charity which raises awareness on menstrual health, said the pledge was "laughable".
"The national government is charging 12 percent tax on sanitary napkins and (lists it) as luxury item," she said.
"Why don't they remove that first?"
Only 18 percent of women in the country use sanitary pads, Akshay Kumar said on Twitter on Thursday, in support of a campaign by Niine Movement, an initiative promoting menstrual hygiene.
"Every female has the right to manage her period safely and with dignity," he said in a statement.