Prior to November 30, 2016, I was just one of the 137 million Americans — specifically, among the 56% of millennials — who relax with a beer, cocktail or spirit at least weekly. But that Wednesday morning was different: The second I opened my eyes and looked up at the ceiling, I knew I wanted to stop drinking.

I chose to give up alcohol for many reasons, and it’s probably those reasons coming together at once that made it an easy decision. All I’d hoped for came true: I had more energy, more mental clarity. I started losing weight and waking up earlier. I felt more optimistic and ambitious about my goals.

I also knew it was going to save me money. I just didn’t realize quite how much.

When you don’t budget, you don’t know

It’s easy to sink a lot of money into anything when you don’t limit yourself as to how much you spend on it. In general, my husband and I follow a reactionary type of budgeting that I’m sure plenty of people do — after a big month, we’ll just say, “We need to spend less on X next month.”

For the most part, it works. And for the most part, we stay on track, diverting money where it needs to go: savings, bills, mortgage, retirement, etc. And the rest, we spend on ourselves.

The realization

After two full months of sobriety, I noticed a huge difference in the “rest we spend on ourselves” part of my budget. Instead of breaking even with our usual spending habits before moving on to the next month, I found a couple hundred dollars left in my account with nowhere to be, just twiddling its thumbs. The next month, the same thing. My curiosity effectively piqued, I decided to run a few numbers.

Doing the math

I use the Mint app to track my spending, mainly so I can take note of trends and pinpoint the “we need to spend less on X” stuff. It’s also convenient for searching by transaction type across multiple accounts. And despite a few improvements I could suggest (hit me up, Mint customer experience department), it’s become an essential tool for my personal financial management.

Sorting by Bars and Alcohol, I found that I’d spent $1,757 on alcohol in the past year. We aren’t big bar people and live at the end of a dirt road, so this doesn’t sound like that much to me. But it also wasn’t a full picture of how much we were spending on suds and spirits.

The hidden math

My husband, because he is the best, chose to join me on my sobriety journey. Note that these figures are for a two-person household. Also, I live in California, where there’s at least one full aisle in the grocery store dedicated to liquor, and eating out at restaurants is a two- or three-night-weekly affair. Because line items are not recorded in credit card purchases (yet), I fooled myself into thinking we just ate a lot.

Tracking the patterns, however, I learned that we were now spending roughly $90 a week on food versus $130 before — a savings of 30%. Swapping four Manhattans for seltzer, we were now spending roughly $80 out to eat versus $140 before — a savings of 42%.

I spent $8,885 on groceries and $3,964 on restaurants in the prior year. So using those same percentages, I found that $2,666 of my grocery budget and $1,665 of my restaurant expenditures were going to alcohol.

That’s slightly less than the 6.8% of other millennials who admit to spending more than $100 a week — or at least $5,200 a year — on drinks. And it’s far less than the 4.5 million Americans who say they spend more than 200 bones a week on alcohol. Still, I took it a step further and went back to 2015.