Just made my main charitable gift for this year. I won't disclose the exact amount of the gift, but the ratios between the numbers below are all accurate.

I donated $1000 of after-tax money to GiveDirectly. I got a 100% match from my employer, so the charity gets $2,000. I grouped 3 years of planned charitable giving all into 2016, so I can take advantage of itemizing deductions (unusual for me), which means I save about 30% on federal and state income taxes, so the cost to me is about $700.

But wait, I donated appreciated stock with a cost basis of only 80% its current value. Donating stock means I avoid paying 15% long term capital gains tax on the 20% of gain, so I saved another $30 of taxes, so the net cost to me fell to $670.

Between the tax planning and corporate match, the charity's benefit ($2000) is three times what it cost me ($670) to give. So efficient!