Parent fundraising groups are pumping a lot of money into San Diego Unified schools, but because the district doesn’t track these nonprofits, we haven’t been able to say how much – until now.

Actually, there are too many holes in the groups’ books to know precisely how much money we’re talking about. But after a lot of homework, I can make a pretty good guess.

School foundations, PTA groups and booster clubs – all nonprofit entities that raise money for schools – brought about $6.5 million to San Diego Unified in 2011-2012. More groups reported their income for that year than for 2012-2013, so I looked there.

The number is likely higher than that. The district doesn’t keep a central database for all nonprofits that work alongside schools, so I pulled their IRS filings one by one.

But not every foundation is named after the school it works with, making it hard to pinpoint just how many foundations exist and who they support. A foundation at Barack Obama Elementary, for example, might be named “Kids Love to Learn and Play” (I made that up).

Some groups were delinquent in filing their reports to the IRS. Others have most likely dissolved, but never bothered to file dissolution paperwork.

Now, $6.5 million is pocket change compared with the district’s mammoth $1.1 billion operating budget. But it’s also nothing to scoff at.

There are a few foundations that raise money for clusters, or collections of schools located in the same general area. But the bulk of that money stays in the particular schools whose parents raised it. This means almost 40 percent of the $6.5 million stays in La Jolla.

Let’s put that $6.5 million into context. That same amount could fund:

• One year’s budget at Central Elementary School

• One year’s salary for about 70 teachers (if they made the district average $92,000, with benefits).

• About 12,115 new iPads (with three-year warranties!)

Again, the total $6.5 million raised by the foundations couldn’t buy those things — that money is like a bunch of gift cards that can only be spent on the school it originated from. But it helps to see how much that amount could buy if it could be bundled together and spent on anything.

Parents and foundations argue that certain schools and clusters have to raise money themselves, because they receive less money per pupil and are short-changed in terms of public funding.

I plan to take a closer look at that claim but for now, it’s important to remember that this fundraised money is unrestricted. Schools can use it for additional teachers, supplemental music or math programs or for fun stuff like field trips.

Schools can also have multiple nonprofits working alongside it. Mira Mesa High, for example, raised about $165,000 in private money from a foundation, a PTA group and a music booster.

La Jolla High has a similar set-up. They just seem to be little better at it. In 2011-2012, fundraising groups brought more than $787,000 to the school.

La Jolla High raised the most in 2011-2012, considering all sources, but if you break the schools down by size, La Jolla Elementary brought in the most per student.

That year, La Jolla Elementary had about $950 to spend on each kid – that’s on top of what it got from the state based on its average daily attendance. That’s a lot, especially considering about 90 schools in the district didn’t report any additional revenue at all.

These 15 schools are the highest earners in the district, in terms of what they brought in through fundraisers. Most are located in La Jolla or Scripps Ranch, although San Diego High near downtown knows how to raise a buck, too. They just have more students who have to share it.