Back to school with 3 kids. Multiply everything by 3. Then remember the one who just graduated.

Two weeks ago I was sitting on a porch in Western Montana watching my kids run around my mom's property at Flathead Lake.

Last week I was floating the Snake River in Wyoming with 17 family members on a Wednesday afternoon.

This week I am staring down back to school shopping for three kids and dreading every single second of it.

The transition from Grand Tetons to Target back to school section is one of the more jarring experiences a parent can have. One minute you're watching bison cross the road in Yellowstone. The next you're debating whether the $4 composition notebook is meaningfully worse than the $7 one while a 10 year old lobbies hard for the one with the holographic cover.

This is also the first back to school season in 18 years where I'm not shopping for four kids. My oldest graduated in June. He's figuring out the next chapter — and for the first time in a long time the back to school list has one fewer name on it.

That's a strange feeling. Not bad. Just strange.

Three kids heading back. One who just closed that chapter for good. This is the life. Wouldn't trade it.

Families with K-12 students are expected to spend an average of $863.86 this year on back to school — a record $43.3 billion total nationally. That's per household, not per kid. Which sounds manageable until you have three kids in three different grades with three different supply lists and three different opinions about what their backpack should look like.

Here's what back to school actually costs when you multiply it out honestly for a family like ours:

Total realistic range for three kids: $1,040 to $1,905

That number is uncomfortable. It's also completely real. And it lands right after a family road trip that cost nearly $5,000. August is not for the faint of heart financially.

Here's how to make it survivable:

Wait on clothes until the last two weeks of July or early August. Retailers discount heavily in late July to clear summer inventory. Clothing spending is up 22% this year even as parents say it's the first category they'd cut if money gets tight. The exact same clothes cost meaningfully less two weeks from now than they do today.

Don't buy electronics until you know exactly what's required. Families are cutting technology spending 16% this year by putting off replacing devices that still work fine. Follow that instinct. A laptop that works is a laptop that works. Replace it when it stops working, not when the new school year starts.

Buy supplies before you see the teacher's list. Get the basics — notebooks, pencils, folders, a backpack. Wait two weeks into school before buying anything specific. Teachers always have a list that's different from the store display. Buying twice costs twice as much.

Set a per-kid budget before you walk into any store. Decide the number per kid before you go. Tell the kid the number. Let them make choices within it. This one habit eliminates most of the back to school financial stress and teaches kids something genuinely useful about money at the same time.

Use the Oregon no sales tax advantage. If you have family or friends in Washington — back to school shopping in Oregon saves them 10.4% on everything. That's $100 back in their pocket on a $1,000 purchase. Worth the drive. Worth mentioning to anyone you know across the border.

The one purchase most parents make too early every single year: Fall clothes. Kids grow. Buying fall clothes in late July means some of them won't fit by October. Buy what they need for the first two weeks of school. Buy the rest in September when you know what actually fits and what the weather is actually doing.

Before you buy a single back to school item — open your notes app and write down every kid's name with three columns: Clothes, Supplies, Other. Put a dollar limit in each column. Add it up. That's your back to school budget. Go into every store knowing that number and you'll spend meaningfully less than the family who walks in without one.

I promised a final road trip financial report. I've been adding up receipts this week. Here's where we landed.

The final trip cost came in under the $4,686 budget. Family hospitality in Montana and Minneapolis saved us roughly $1,500 in lodging and meals. The America the Beautiful pass — which my 4th grader got free through the Every Kid Outdoors program — saved us over $100 in park entry fees. The Tetons Airbnb split with family came in exactly as budgeted.

The budgeting exercise worked. Not because it made the trip cheaper — it didn't. It worked because we knew the number going in and never once stressed about money on the road. Every gas station, every restaurant, every rafting trip happened without financial anxiety attached to it.

That's what a budget actually buys you. Not restriction. Permission.

If you missed the road trip series — issues #010, #011, and #012 are all on the web at fourkidslater.com. Montana, Minneapolis, the Grand Tetons, and 17 people on the Snake River in Wyoming. It was the trip of a lifetime and I'm already thinking about the next one.

Last Wednesday I was in a raft on the Snake River in Wyoming with my youngest kids and my oldest son who just graduated. The mountains were behind us. The water was cold. Nobody was thinking about back to school.

This Wednesday I need to buy three kids' worth of school supplies.

Three. Not four. For the first time in 18 years.

My oldest graduated in June. He was on that river with us. He sat around the table at the Tetons Airbnb with the whole family. He rode quads on the ranch in Grass Range Montana where his grandfather grew up. He was there for all of it.

And now he's not heading back to school in August for the first time since he was five years old.

That's a strange thing to sit with in the school supply aisle. Not sad exactly — he's starting the next chapter and that's what's supposed to happen. Just different. The kind of different you don't fully anticipate until you're standing there counting supply lists and coming up one short.

Three kids. Three supply lists. One dad who just got back from the best road trip of his life and is now trying to remember if the 7th grader needs a three-ring binder or a five-subject notebook.

Five-subject. It's always the five-subject.

The fall sports season is starting back up — registration fees, gear, travel. We're building the Four Kids Later Fall Sports Budget before the bills start arriving. Plus the one financial move every parent should make in August before the school year starts.