You've probably seen it happen: someone buys beautiful curtains that end up too short, or installs a rod that starts sagging within weeks. These problems usually come from skipping important decisions early on. This guide shows you what to figure out first.

Figure Out What You Need

Before you measure anything, think about why you're doing this. Your main goal changes every other decision.

If privacy is the issue, you'll want heavier fabrics and rods that extend well past the window frame so there are no gaps. Decorative details matter less here. Privacy curtain strategies

For blocking light completely, regular curtains won't cut it. You need specific mounting techniques and fabric that extends way beyond the window edges. Blackout installation methods

Just decorating? Then you have way more flexibility. Focus on getting the proportions right and picking a style you like. Decorative curtain ideas.

Trying to save on heating and cooling? The curtains need to actually seal against the wall. Standard rods leave gaps on the sides that let air through. 

Pick Your Mounting Style

This choice affects literally every measurement you'll take, so decide this first.

Inside mount means the curtain fits inside the window frame itself. Looks clean and shows off nice trim work. But you need at least 2-3 inches of frame depth for the hardware, and you'll always have a light gap around the edges. Works great for cafe curtains in kitchens.

Outside mount puts everything on the wall above the window. This is what most people end up doing. It makes windows look bigger, blocks more light, and hides ugly frames. You just need solid wall space above and around the window.

Ceiling mount attaches to the ceiling instead of the wall. Fixes weird spacing problems and creates a dramatic floor-to-ceiling look. Needs different hardware than the other options.

Can't decide? Outside mount is usually the safest bet. Compare all mounting options

Choose How They'll Hang

The hanging style determines how high your rod sits and how long the curtains need to be. Grommets slide directly on the rod through metal rings - easy to open and close with a modern look. Rod pocket means the rod goes through a sewn channel at the top, more traditional but harder to move daily. Back tabs hide the rod from the front view for a clean appearance, though they only work with lighter fabrics. Pinch pleats need rings or clips and give you that professional look with controlled fullness. Track systems use gliders in a channel for smooth operation with heavy curtains.

Each style hangs a bit differently from the rod, which matters when you're measuring. See all hanging styles explained

Work Out Rod Placement

Where you put the rod changes how the whole thing looks.

For standard 8-9 foot ceilings, start 4-6 inches above the window frame. Higher ceilings? You can go 8-12 inches up. Want maximum height drama? Mount just a few inches below the ceiling. Going higher makes windows look bigger, but there's a point where it starts looking off.

Width matters just as much. The rod needs to extend past the window so curtains can stack to the sides when open. Add at least 4-6 inches on each side for basic stack-back. Want the window fully visible when curtains are open? Add 8-12 inches per side. Going wider also helps with light blocking since the curtains can overlap more wall. Rod height and width details

Measure Everything

Here's what you actually need:

From your mounting point down to the floor - this gives you rod height. Total rod width including those extensions past the window. From the rod down to where you want curtains to end. And the window width itself for calculating how much fabric you need.

Most people only measure the window and wonder why nothing looks right. You're not just covering the window, you're creating a whole look around it.

Use a metal tape measure, not cloth. Write everything down. Measure twice because you're going to buy once. Full measuring instructions

Decide on Length

Sill length stops right at the window sill - good for kitchens and anywhere you have a radiator or furniture below. Apron length goes 4-6 inches below the frame, a traditional choice for casual rooms.

Floor length is what most people pick. You can have them just kiss the floor, create a small half-inch puddle, or go for a dramatic 2-3 inch puddle. Longer usually looks better, but think about your actual life. Got pets? That dramatic puddle will be a dirty mess in a week.

Calculate Width and Fullness

Curtains look cheap when they're stretched flat across the window. You need enough fabric to create folds.

At minimum, get 1.5 times your window width, though curtains will look pretty flat when closed. Two times the width gives you nice folds without going overboard - this is the sweet spot for most people. Want that luxurious magazine look? Go 2.5 to 3 times the width, but it costs more.

Don't forget stack-back space. When you push curtains open, they need somewhere to go. Lightweight sheers need about 10 inches per side. Heavy fabrics like velvet or blackout need 15-20 inches per side. Skip this and your curtains will always block part of the window even when "open." Calculate your exact needs

Get the Right Hardware

Pick hardware based on what it can actually hold, not just how it looks. That pretty decorative rod won't matter when it's bent and your curtains are on the floor.

Basic rods work fine for lightweight stuff like sheers or unlined cotton. Standard curtains with lining need sturdier rods and decent wall anchors. Heavy curtains - blackout, velvet, thermal backed - require commercial-grade hardware or you'll have problems.

Any rod over 4-5 feet needs a center support bracket. Over 6 feet? Add support brackets every 3-4 feet or expect sagging. Your wall type matters too. Drywall needs different anchors than plaster or concrete. Those little plastic anchors that come in the hardware package? They're usually garbage for anything heavier than sheers. Hardware selection guide

Installation Options

You can DIY this with basic tools - drill, level, and some patience. First window takes about an hour while you figure it out. After that, maybe 20-30 minutes each. Works fine for standard drywall and normal-weight curtains. 

Renting and can't drill? Tension rods actually work for lightweight curtains in narrow windows. Magnetic rods work if you've got metal door frames. Command strips are fine for valances that don't move. But skip adhesive brackets for curtains you'll actually use daily - they will eventually fail. Renter-friendly options

Professional installation makes sense for concrete or brick walls, really high windows, expensive custom curtains, or when you're doing multiple windows and want them consistent. Expect to pay anywhere from $75-200 per window depending on your area and complexity. Big cities and difficult installs cost more. 

Different Rooms Need Different Approaches

In bedrooms, focus on blocking light. Mount outside the frame, extend past the edges, let curtains touch or puddle on the floor. Consider wraparound rods to eliminate those annoying side gaps.

Living rooms need flexibility - open for light, closed for privacy or TV glare. Layering sheers with heavier curtains gives you options. Decorative hardware actually matters here since everyone sees it.

Keep kitchen curtains short and washable. Sill length prevents cooking splashes. Synthetic fabrics handle moisture better than natural fibers. Cafe curtains give you privacy without blocking all your light.

Bathrooms mean moisture. Use synthetic fabrics, mount high enough to avoid shower splashes, make sure you have good ventilation. Inside mount often looks cleaner in small bathrooms. Room-by-room suggestions

Tricky Window Situations

Bay windows need either curved rods or separate sections joined with connectors. Ceiling mount often works better than trying to mount on those angled walls.

Arched windows usually look best with the arch exposed and curtains mounted at the straight part below.

Sliding glass doors need a one-way draw so all the curtains stack to one side. Make sure you have enough wall space on whichever side you choose.

Multiple windows in a row look better with one continuous rod rather than separate treatments on each window. Special window solutions

Fixing Common Problems

Curtains too short? Add a contrasting band at the bottom and make it look intentional.

Too narrow and stretched? Buy more panels. Better to have too much fabric than sad flat curtains.

Rod sagging already? Add a center bracket now before it bends permanently.

Light leaking around the edges? You need wraparound rods or side channels. Regular rods always leave gaps.

Brackets pulling out of the wall? Your anchors are too weak. Upgrade to toggle bolts or find the studs. Fix curtain problems

Before You Buy Anything

Make sure you actually know: why you're adding curtains, how they'll mount (inside/outside/ceiling), how they'll hang (grommets/rings/tabs), where the rod goes (height and width), your actual measurements, what length you want, how much fullness you need, and whether your hardware can handle the weight.

Not sure about something? Go back to that section. Getting this order right saves you from expensive mistakes.

Where to Go Next

Never done this before? Start with How to Measure for Curtains

Ready to install? Check out the DIY installation tutorial or renter solutions if you can't drill.

Picking hardware? Compare your options.

Got weird windows? Special situation guide.

Still planning? Look at mounting style comparison,  choosing curtain length.