At 2am you are not going to type 'is my guest room big enough.' You are going to type something closer to 'can Mom sleep over without the kids losing their minds.' Good news: the first half of that question can be answered with a tape measure and a cup of coffee. The second half takes a little longer, but it starts with the same walk-through.

Measure the route, not just the room

Most people walk into the guest room, see a bed, and decide it fits. The room is the easy part. Walk the route Mom will take on a normal morning: bed to bathroom, bathroom to kitchen, kitchen to the chair where she likes to sit. Measure the narrowest doorway on that route with a tape and write the number down. Then walk it again carrying what she will actually carry, a bag in each hand, because that is what a real morning looks like.

Check the floor while you are down there. A rug that slides, a step between rooms, a threshold you forgot about until you were in the dark. Note every one. You are not fixing the house tonight. You are making a list of what the house asks of her, so you can decide which items you can change and which ones she will simply have to step around.

Count the bathroom

This is where the fit usually breaks. Ask whether the bathroom she will use is on the same floor as her room. If it is shared with three kids and a school-morning rush, decide before she arrives who gets it first, who gets it last, and whether there is a set window for her. Look at the tub or shower entry, the toilet height, and whether there is a clear place to stand that is not the bath mat in the hallway. Put the things she uses every morning on one shelf at a height she can reach from where she will stand. Not on the top shelf where the kids keep the shampoo collection.

Give the kids their square footage back

Every guest room comes from somewhere. If the room you are offering was the kids' homework table, the play corner, or the place the dog sleeps when it storms, the kids are the ones who lose the space. Name that out loud before you move anything. Ask each kid what they would lose and what they would get back. A kid who keeps their bedtime routine and gets to pick the Saturday movie is a lot less likely to start a campaign against Grandma.

Also check the sound. Can the kids' rooms hear her television? Can she hear the dishwasher at 5am? A door that closes, a white noise machine, or a rule about who gets up first can fix most of it. If none of those work, the room is probably not the right room for this plan, and that is information you want before the weekend, not during it.

Test the night, not only the day

Mornings are the easy part to imagine. Nights are where the surprises live. Walk the path from her bed to the bathroom in the dark. Is there a light that turns on without a scavenger hunt? Are the kids' bathroom light and the hallway light on the same switch? Can she find the door out of the room without stepping on a toy? Set up a night light, leave the path clear, and walk it yourself with the lights off. You will learn more in five minutes than in five days of planning.

Ask her what she needs, and write it down

Mom will probably say she does not need anything. Ask a different question instead: what do you use every morning, what do you need to reach in the dark, and what do you always bring with you? Write the answers on the same list as your measurements. Then compare the two lists. The gaps between what she needs and what the room offers are your real to-do list, and they are almost always smaller than they look at 2am.

Decide the length before you decide the room

A weekend is not the same as a month. Pick a first stay short enough that everyone can survive it and long enough to learn something. Two nights is a reasonable trial for most families. Write down what you want to check on each day: the bathroom at 6:30, the kids' homework time, the drive to school, and what happens when someone needs a quiet hour. If one check fails, that is not you failing. It just means the plan needs a different room, a different schedule, or a shorter visit.

If you want to see how the two calendars sit next to each other before you pick a weekend, start with The Kids' Week and Mom's Week. It shows the same week from both sides, which makes the sleepover decision a lot easier to plan.