Giving Tuesday, the anti-Black Friday day for charitable donations, comes on the heels of Cyber Monday. If you’ve never heard of it before, that’s because it is only a few years old, founded in 2012 by the 92nd Street Y and the UN Foundation in response to post-Thanksgiving materialism—and the fact that December is your last chance for a tax-deductible donation before the new year arrives.

Last year, around 700,000 people donated $116.7 million.

Unfortunately, many people just don’t have the patience to deal with a sea of charities—and others don’t really have much to give. This leads many people to the inevitable question: What are the most efficient charities to support?

Give Well has dedicated itself to this very question since 2007, using copious research and a critical process to determine exactly where the dollars are needed the most. The utilitarian philosophy prioritizes effectiveness per dollar, perfect for someone looking to maximize their giving.

Of course, this sort of strategy may not be right for everybody. Exchange rates, trade, and different living standards mean dollars save more lives and have greater impact if shipped abroad, and many people like to support their own communities, national organizations, or pet causes.

If you’re looking purely to save lives, it’s hard to argue with Give Well’s top-rated charity, Against Malaria Foundation. Cheap nets for people in the developing world who are exposed to malaria directly save lives and improve health. According to Give Well, around every $3,500 donated saves a child’s life. This may sound like a lot; you might have heard incredible statistics that a $5 net can save a child’s life. Of course, a $5 net can save a child’s life, but Give Well notes that simplistic calculations that assume too much inflate the value of a single dollar by ignoring much of the picture.

Still, it’s an incredible value—Give Well notes that some of the best domestic programs come in at around $10,000 per life affected.

A few other charities make the Give Well cut for being recommended in terms of excellent value and need. Schistosomiasis Control Initiative deworms a child for just $1.26 each, and they could use more money. Expanding past sub-Saharan Africa worm issues is Deworm the World, which de-worms children for around 79 cents each. Around 1.5 billion people, a quarter of the world’s population, are affected by soil-borne worms, impairing hundreds of millions of children, according to the World Health Organization.

Give Well has one other organization on its list, which is a little bizarre. It’s called Give Directly, and it does exactly what it sounds like: It gives money to those in extreme poverty in places like Kenya and Uganda. After a cash transfer, they themselves decide what they need and buy it.