If an advertiser moved 6% of its TV ad spending in to online video, how many more viewers would it reach?

That’s the question online ad tech outfit YuMe is trying to answer by launching its Multi-Screen Reach Calculator, a web app that lets ad planners play with various spending scenarios across different devices.

“We keep getting asked often, ‘How do I calculate reach?’,” says Redwood City, CA-based YuMe‘s marketing SVP Ed Haslam. “We have the tools to do that for online – but there are no tools out there right now to do that across smartphones, tablets and connected TVs.”

To make the “reach-alator”, YuMe crunched the findings of a Nielsen research effort in to the effect of multi-screen ad buying, which found 87% of consumers use devices while the TV is on.  More on today’s news in this company press release.