Over $4 billion of New Zealanders' KiwiSaver money is invested in sin stocks, weapons makers and unethical companies, according the social enterprise behind a new online search tool.

Barry Coates, a former Green Party MP, has launched Mindful Money which breaks down the investments in KiwiSaver's 260 funds and shows people what percentage of their fund is invested in 10 controversial areas.

Until now KiwiSaver members have been able to see the companies they invest in but have had to do their own research to find out what sectors or practices the companies are involved in.

Coates said