The state’s mass transit agency has been asking residents how to solve its immediate $161 million deficit (and even bigger ongoing deficit) — with riders facing higher costs and less service as a killer incentive — but now the Metropolitan Area Planning Council has made it a little more, well, fun.

The council has launched an interactive MBTA Budget Calculator at fixthet.mapc.org.

“This tool allows you to mix and match different elements from the MBTA’s own proposals to fill the budget gap, along with additional revenue and savings options proposed by the MBTA Advisory Board and others,” said Amanda Linehan, the council’s communications manager.

Cambridge hosted a hearing Feb. 29 with legislators and Massachusetts Bay Transit Authority — one of 30 the agency is holding in communities throughout its service area — at which some 125 people spoke, many with ideas about where to find a few million here, a few million there. Some has suggestions as simple as making all riders pay their fares, as T workers may have been too casual about it in the past, and holding other services accountable for their failings. Fines for missed commuter rail schedules have been foregone for The Massachusetts Bay Commuter Railroad Co. and Veolia Transportation North America in what some called a “sweetheart deal,” for instance.

City officials had their own list of suggestions, which state legislators such as Sen. Sal DiDomenico praised as “probably the best we’ve seen.”

But it’s not clear what will be adopted or how in time to keep fares and services where commuters want them.

“MAPC created this budget calculator to collect these ideas in one place and give people an opportunity to come up with their own plan. Even better, the website includes a link that allows users to share their ideas with their legislators,” Linehan said.

The Massachusetts Bay Transit Authority plans to adopt a budget by April 15.