Measure, pin, and sew a straight line to hem pants
Hemming pants on a sewing machine takes about 20 to 30 minutes once you have the right measurements. You will need the pants, a measuring tape, pins, thread that matches the fabric, and a sewing machine with a straight stitch. The basic process is: try on the pants at the length you want, mark that line with pins, fold the fabric up to create the hem, and sew along the fold with a straight stitch about a quarter-inch from the edge.
The most common mistake is measuring while sitting down or in shoes you will not actually wear. Stand in the shoes you plan to wear with the pants, have someone else measure from the floor to where you want the hem to hit, or mark the length yourself by looking in a mirror. Write down that measurement — do not rely on memory.
Key Takeaways
- Measure the pants while standing in the shoes you will wear them with, and mark the desired length with pins all the way around the leg.
- Fold the fabric up along your pin line, press it flat with an iron, and pin the fold in place before you sew.
- Use a straight stitch on your machine, sew about a quarter-inch from the folded edge, and backstitch at the start and end to lock the thread.
- Try on the pants after hemming to check the length before you cut away the extra fabric.
Mark the hem line with pins while wearing the pants
Put on the pants with the shoes you will wear them with most often. Stand in front of a mirror or have someone help you. Measure up from the floor to where you want the hem to sit — usually the pants should just touch the top of your shoe or break slightly on the instep. Use a measuring tape or a ruler held against your leg.
Once you have the measurement, mark that line all the way around the leg with pins. Push the pins through both layers of fabric so they go in horizontally — this keeps them from falling out while you work. Mark both legs, even if they seem the same length, because legs are often slightly different.
Take off the pants carefully without moving the pins. Lay them flat on your work surface with the inside facing up so you can see the pin line clearly.
Fold and press the hem before sewing
Fold the fabric up along the pin line so the wrong side (the inside) of the hem faces outward. The fold should be crisp and even all the way around. If the fold is uneven, adjust the pins until the line is straight.
Use an iron set to the heat level for your fabric — check the care tag on the pants if you are unsure. Press the fold flat with firm, even strokes. This crease helps the hem stay in place while you sew and makes the final stitch look neater. Let the fabric cool for a moment before you move it.
Pin the folded hem in place with pins running perpendicular to the fold — that is, pins that go across the hem rather than along it. Space them about two inches apart. These pins hold the hem steady while you feed it through the machine.
Thread the machine and set the stitch
Wind a bobbin with thread that matches your pants fabric as closely as possible. Thread the top of the machine with the same color. If you cannot find an exact match, choose a shade slightly darker rather than lighter — it is less visible in the finished hem.
Set your machine to a straight stitch with a stitch length of about 2.5 millimeters. This is a standard length for most fabrics and creates a seam that is strong but not so tight it puckers the fabric. Check your machine's manual if you are not sure how to adjust stitch length — the dial or button is usually on the front of the machine.
Test the tension on a scrap of the same fabric before you hem the pants. Sew a short line and look at both sides — the stitches should look the same on top and bottom. If the top thread is loose or the bottom thread is bunched, adjust the tension dial slightly and test again.
Sew the hem with a straight line
Position the pants under the presser foot so the needle will go about a quarter-inch from the folded edge of the hem. This distance keeps the stitch close enough to hold the hem but far enough from the edge that it will not show when you wear the pants. Lower the presser foot to hold the fabric in place.
Backstitch three or four stitches to lock the thread at the start. Then sew forward slowly, keeping the fold line straight under the needle. Remove pins as you approach them — do not sew over them, as this can break the needle or damage the machine.
When you reach the end of the leg, backstitch three or four stitches again to lock the thread. Raise the presser foot and remove the pants. Repeat for the other leg.
Trim the excess fabric and finish the edge
Try on the pants to check the length before you cut anything. If the hem looks right, lay the pants flat and trim the excess fabric to about half an inch above the stitching line. Use sharp scissors or a rotary cutter and ruler for a straight cut.
Finish the raw edge to prevent fraying. The simplest method is a zigzag stitch: set your machine to a zigzag pattern and sew along the cut edge, letting the needle swing over the edge of the fabric. This seals the fibers and keeps the hem from unraveling in the wash. Alternatively, use pinking shears — special scissors that cut a zigzag pattern — to trim the edge instead of straight scissors.
Press the finished hem one more time with an iron to flatten it. The hem is now complete and ready to wear.
Common problems and how to fix them
Puckered or wavy hem: This usually means the tension is too tight or you are pulling the fabric while sewing. Loosen the top tension slightly and let the machine feed the fabric at its own pace — do not push or pull. If the fabric is stretchy, use a ballpoint needle instead of a regular sharp needle.
Uneven hem length: The pants may not have been measured correctly, or one leg may be longer than the other naturally. Measure and mark each leg separately rather than assuming they are the same. You can also hem each leg to a different length if needed.
Stitches breaking or skipping: The needle may be bent, dull, or inserted incorrectly. Replace the needle with a fresh one — needles are inexpensive and wear out quickly. Make sure it is inserted all the way up into the needle clamp and facing the correct direction for your machine.
Thread bunching on the underside: The bobbin tension is too loose or the bobbin is not wound evenly. Rewind the bobbin and make sure it is inserted correctly into the bobbin case. If the problem continues, adjust the bobbin tension screw slightly — turn it clockwise to tighten.
Frequently Asked Questions
Can I hem pants without an iron?
Yes, but the hem will be less neat and may shift while you sew. If you do not have an iron, fold the hem carefully and pin it very securely with pins close together. Sew slowly and let the machine do the work without pulling the fabric. The finished hem will still hold, but the fold line may not be as crisp.
What thread color should I use?
Match the thread to the fabric color as closely as possible. If the pants are a solid color, use thread in that same shade. For patterned fabric, choose a color that appears in the pattern or matches the dominant color. Thread slightly darker than the fabric is less visible than thread that is too light.
How wide should the hem be?
A standard hem on pants is one to one and a half inches wide. Measure from the fold line to the cut edge. Narrower hems work for lightweight fabrics, while heavier fabrics like denim may need a slightly wider hem for strength. Check the original hem on the pants if they came with one — you can match that width.
What if the hem is crooked after I sew it?
Remove the stitches with a seam ripper, re-measure and re-pin the hem, and sew again. It is faster and easier to redo it than to try to fix a crooked hem. Seam rippers are inexpensive and come with most sewing machines.
Do I need to finish the raw edge if the pants are already hemmed?
If you are replacing an existing hem, you can trim the old hem away and finish the new edge with a zigzag stitch or pinking shears. If the pants are new and the original hem is still there, you do not need to finish the edge again — just sew your new hem on top of the old one.