Peak body Volunteering Australia has announced the theme for National Volunteer Week 2019 will be 'Making a World of Difference'.

Volunteering Australia policy manager Lavanya Kala said this year's National Volunteer Week theme stresses the incredible impact volunteers make at a local, national and global level.

"Volunteers donate an estimated 734 million hours of time each year to the community," she said.

"This volunteering yields a 450 per cent return for every dollar invested.

"Nationally this is an estimated annual economic and social contribution of $290 billion."

National Volunteer Week will run from May 20-26, 2019. Thousands of events will be held across Australia to say thank you to the six million formal volunteers and many more informal volunteers who give their time.

The week-long celebration includes breakfasts, morning and afternoon teas, luncheons, open days, award ceremonies, picnics, forums and training sessions to acknowledge and recognise how volunteers make a world of difference to Australian communities.

"National Volunteer Week provides an important opportunity to reflect, acknowledge and celebrate the achievements of the many volunteers that span across different sectors and organisations," Ms Kala said.

"From the arts, sport, emergency services, aged care, disability support, mental health, community transport, the environment, corporate volunteering and community services; volunteers are inextricably woven into the fabric of everyday life and Australian society is very dependent on the support provided by these unsung heroes."

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This year also marks 30 years since National Volunteer Week began in 1989.

To mark the occasion, Volunteering Australia has released a special edition commemorative 30 years of National Volunteer Week pin, on sale in its online shop.

National Volunteer Week is also an important occasion to think about how volunteers are indispensable socially, culturally and economically across the country.

Are you interested in becoming a volunteer?

Volunteering Australia encourages would-be volunteers to visit www.govolunteer.com.au, Volunteering Australia's national database of volunteering opportunities.

Visit your state or territory peak body to connect with your local volunteering support service and find a suitable volunteering opportunity.