'Living wage': One in four Welsh workers earns less
One in four Welsh workers earns less than the UK "living wage" calculated to cover the basic costs of living.
The voluntary rate of £7.85 an hour set by university researchers is 21% higher than the legal minimum wage of £6.50.
Wales TUC national officer Julie Cook said low pay was "blighting the lives" of hundreds of thousands of families.
Business organisation CBI Wales said living wages were a useful guide but many firms could not afford to pay more than the minimum wage.
The UK government said it supported firms who paid the living wage "only when it is affordable and not at the expense of jobs".
Around 261,000 workers in Wales are thought to earn less than the living wage, according to the latest annual report on the matter by KPMG.
Across the UK 22% of workers are said to earn less than the living wage, with Northern Ireland worst off with 27%.
The voluntary rate has been adopted by more than 1,000 employers across the UK, benefiting 35,000 workers.
Ms Cook called for people to be given "a fair day's pay for an honest day's work", saying it would help boost the economy.
She said: "It is now time for all responsible employers to commit to adopting this standard, which enables workers to earn just enough to be able to live a decent life."
The UK living wage is calculated by the Centre for Research in Social Policy at Loughborough University, while a higher rate for London is calculated by the Greater London Authority.
CBI Wales Director Emma Watkins said living wages could be a "useful guide" but stressed that the national minimum wage enjoyed "strong support" from the business community.
She added: "Rather than requiring firms to introduce pay rises that many cannot afford, we must look at ways to raise living standards sustainably."
A spokesperson for the UK Department for Business, Industry and Skills said: "We support businesses that choose to pay the Living Wage, however only when it is affordable and not at the expense of jobs."