That Rotary members log a lot of volunteer hours should come as no surprise to anyone familiar with the organization. But a new report just released by Johns Hopkins University provides a powerful look at the impact of all those volunteer hours.

The special report prepared for Rotary International by the Johns Hopkins Center for Civil Society Studies found that Rotary members had volunteered a total of 5.8 million hours within a four-week survey period. Extrapolating those results over an entire year, the report gave a conservative estimate of nearly 47 million hours of volunteer effort generated by Rotary members in a typical year.

The report then analyzed the economic impact of all those hours and estimated the value conservatively at $850 million a year, if communities had to pay for the services that Rotary volunteers provide.