How to Sew Corners (Clipped, Boxed and Mitered)

Why Corner Techniques Matter for Bag‑Making and Small Sewing Projects

This guide shows you how to sew corners using the three most common techniques: clipped, boxed and mitered.

If you sew bags, pouches or small accessories, the quality of your corners makes a visible difference to the overall finish. Crisp, structured corners make a handmade item look intentional and professional, while bulky or rounded corners can make even a well‑sewn project appear untidy.

For anyone learning bag‑making, understanding how to sew corners properly is one of the core skills that unlocks better results immediately. It is also one of the most common problems beginners search for, which is why this tutorial attracts high‑intent readers who often go on to download sewing patterns and guides.

This post covers the three main techniques used in bags and small projects:
• Clipped corners (used frequently in beginner projects)
• Boxed corners (used to create depth in make‑up bags and pouches)
• Mitered corners (mainly used in home décor)

Where relevant, I have included natural links to the sewing PDF guides that use these techniques.

What Are the Three Main Corner Types?

Before going deeper, here is how each technique works and where you will see it used.

Clipped corners: Used when turning a project right side out to remove bulk so the point sits cleanly. Common in beginner sewing projects and many small projects. My simple drawstring bag step-by-step guide uses clipped corners as part of the construction.

Boxed corners: Used to give depth and shape to make‑up bags, pouches, storage bags and some totes. If you want to practise this technique, my boxed zipper pouch tutorial takes you through the full method with no binding.

Mitered corners: A clean angled finish used in placemats, napkins and home décor. Useful to learn, but not used in my current PDF guides.

How to Sew Clipped Corners

Clipped corners are the quickest way to achieve sharp points after turning a project right side out. They are used widely in small projects and are ideal for beginners.

When to Use Clipped Corners

• Drawstring bags
• Small pouches
• Wallets, coin purses and small accessories
• Linings that need clean, defined points

If you want a project to practise clipped corners, my simple drawstring bag tutorial is designed for beginners and includes this step naturally.

Step-by-Step: Clipping Corners Cleanly

1. Sew your seams using the recommended seam allowance.
2. Press the sewing line gently to set the stitches.
3. Trim across the corner at a 45-degree angle, leaving a small margin so you do not cut through the seam.
4. Turn the project right side out.
5. Use a turning tool or knitting needle to gently push the corner outward.
6. Press the corner so it holds a crisp shape.

Clipped corners are one of the simplest techniques, but mastering them immediately improves the overall finish of your projects.

How to Sew Boxed Corners

Boxed corners are used when you want a bag or pouch to have a flat base. They are perfect for make‑up bags, storage pouches and any project that needs depth.

If you'd like a beginner‑friendly project that uses boxed corners, my boxed zipper pouch tutorial guides you through the full construction without binding.

When to Use Boxed Corners

• Make‑up bags
• Storage pouches
• Organisers
• Small baskets

Two Methods for Sewing Boxed Corners

1. The cut‑out method (beginner‑friendly)
A square is removed from each corner, and the remaining edges are brought together and sewn. This is the method most commonly used in beginner sewing patterns.

2. The fold‑and‑sew method
The corner is folded into position rather than cut. This method reduces fabric waste but requires accurate folding.

Step-by-Step: Boxing Corners

1. Decide how deep you want the base to be.
2. Mark and cut out identical squares from each bottom corner (or fold instead of cutting).
3. Bring the raw edges together, matching seams precisely.
4. Pin firmly so the seams do not twist.
5. Sew across the opening and press.

Boxed corners give structure and help a bag stand up, which is one reason they feature in many intermediate bag‑making projects.

How to Sew Mitered Corners

Mitered corners are commonly used in flat sewing projects where the edges need a polished finish.

When to Use Mitered Corners

• Placemats
• Napkins
• Tea towels
• Fabric gift wraps

Step-by-Step: Creating a Mitered Corner

1. Press your hems in place around all four edges.
2. Open out the folds and trim the corner so it lies flat.
3. Fold the fabric diagonally so the raw edges align.
4. Refold the hems and press.
5. Topstitch for a clean finish.

Although not used in my current PDF guides, this technique is useful to learn if you want high‑quality finishes in home décor sewing.

Common Problems With Sewing Corners (and How to Solve Them)

Bulky corners that do not turn properly
Trim the seam allowance more closely. Using lighter interfacing also helps.

Corners that collapse or dent
Ensure the corner is clipped correctly and pushed out fully before pressing.

Uneven boxed corners
Check that all cut squares are the same size and that the seams align perfectly.

Rounded clipped corners
You may need to trim a little closer to the stitching, but always leave a safe margin.

Troubleshooting is part of learning, and improving corner techniques often transforms the quality of your finished projects.

Practical Tips for Achieving Sharp, Professional Corners

• Press as you sew — it makes a dramatic difference.
• Use a turning tool gently to avoid punctures.
• Shorten the stitch length slightly around corners for better control.
• Choose interfacing weights that add stability without excessive bulk.

These refinements help your handmade items look more finished and more structured.

Which Corner Technique Should You Learn First?

If you’re a beginner, start with clipped corners. They are simple, widely used and appear in many small sewing projects. My simple drawstring bag step-by-step guide is ideal if you want a straightforward project to practise this.

Once you're comfortable, move on to boxed corners, especially if you want to make make‑up bags and pouches. The boxed zipper pouch tutorial is a suitable next step.

Mitered corners can be explored later when moving into home décor.

FAQ

How do I stop my corners looking rounded?
Rounded corners usually happen when the seam allowance isn’t trimmed closely enough. Clipping the corner more neatly and pressing firmly will create a sharper point.

Why are my boxed corners uneven?
Uneven boxed corners are almost always caused by cut-out squares that aren’t identical or seams that don’t align. Measuring carefully before cutting solves this.

What stitch length should I use when sewing corners?
A slightly shorter stitch length (around 2.0–2.2 mm) gives better control when sewing around corners and helps maintain a crisp shape.

Do I press corners before or after turning?
Both. Pressing the seam before turning helps set the stitching, and pressing again afterwards helps the corner hold its shape.

Want a Project to Practise These Corner Techniques?

Here are projects that match each skill:

• Clipped corners: The simple drawstring bag tutorial uses clipped corners naturally within the construction and is perfect for new sewists.

• Boxed corners: The boxed zipper pouch tutorial walks you through sewing boxed corners with no binding, making it a great next step.

Each guide is designed to build confidence and help you progress from beginner techniques to more structured projects.