Buttonholes, zippers, snaps and elastic: how to sew closures

Buttonholes sized from the button, a centered zipper, snaps and hook-and-loop tape, elastic casings fitted on the body, and drawstring limits for anything made for a child.

1. Buttonholes sized from the button Understand

A buttonhole is a slit through the fabric with its edges covered by stitching, long enough for a button to pass and short enough to hold it. Sewing.org's beginner lesson, credited to the Singer Reference Library, makes the point most beginners miss: the buttonhole marks on a pattern give its position, not its length. The button sets the length. Both NMSU's Guide C-231 and the University of Idaho's buttonhole bulletin say to have the actual buttons before you make any buttonholes (NMSU Guide C-231; University of Idaho CIS 602, 1983).

How long

A button has to pass through sideways, so both its width and its thickness count. Start from the button's diameter plus its thickness, the rule in the University of Idaho's bulletin, sewing.org's lesson ("as a general rule") and Brother's one-step buttonhole page. For a 3/4 in button 1/8 in thick that is 7/8 in (2.2 cm); sewing.org's worked example is a 7/8 in button 1/8 in thick needing a 1 in buttonhole. Convention Another source adds 1/8 in for the fabric, which matters on a button that size, so this is the length of your first test, not the final one. For dome, ball and covered buttons the sources agree on a test buttonhole on scrap. The buttonhole calculator gives the length.

The test buttonhole settles it

NMSU's guide says to make a test buttonhole first on a scrap, with the same layers the project will have (fabric, interfacing or stabilizer, facing). Sewing.org says to make a test buttonhole too, and for covered, domed or odd-shaped buttons to cut a slit in a swatch and lengthen it until the button slides through easily. Idaho's bulletin tests machine buttonholes through all the layers involved. NMSU and sewing.org both make the test first, every time, and this manual agrees: sew the test. Test it

1. Build the test piece from two layers of the project fabric with interfacing between or fused to one, as the project will be. NMSU interfaces both the button and the buttonhole areas; Idaho stabilizes stretchy fabric with fusible nonwoven interfacing (interfacing).
2. Mark the length from the formula you chose, with a line across each end.
3. Sew the buttonhole the way your machine's manual shows (one-step or four-step, below).
4. Put a pin across each end as a stop, then cut the slit open from the middle toward each end with a seam ripper or small sharp scissors, as the CAERT unit does. Sewing.org runs the point backward between the two rows of stitching first, to separate the threads before cutting.
5. Push the button through. It should pass without forcing and stay buttoned when you tug the fabric. If it has to be forced, sew a longer test; if it slips out, a shorter one.
6. Write the length that passed on the test piece and on the settings sheet (stitch: buttonhole), with the fabric and interfacing.

NMSU advises erring on the short side when cutting the slit: once cut through, try the button, and cut further only if it needs it.

One-step and four-step buttonholes

A one-step buttonhole is sewn in one pass with a buttonhole foot that measures the button. On the machine shown in Brother's one-step page, you put the button in the foot's holder plate; the page gives a maximum length of about 28 mm (about 1 1/16 in) as diameter plus thickness, and for odd-shaped buttons it sets the plate to that sum instead (Brother, one-step buttonholes). Brother's page does not name the model, so treat its 28 mm as one machine's limit. A four-step buttonhole is sewn in stages: one side, a bar across the end, the other side, a bar across the other end, each chosen in turn on the dial. You decide the length by where you stop each side. Your manual gives the steps, the order and any length limit for your machine. Product-specific

Placement and spacing

• Direction. NMSU sews vertical buttonholes on the center front or back line, and starts horizontal ones 1/8 in past the center line toward the edge, so the button sits on the center line when buttoned. Idaho uses horizontal buttonholes on fitted garments, because strain pulls across them.
• Spacing. NMSU gives 2 to 3 1/2 in apart as standard placement, a buttonhole at the bust line on a blouse to keep it from gaping, and a seam gauge for even spacing. If a pattern is lengthened or shortened, NMSU and sewing.org both respace the buttonholes, keeping the top and bottom positions.
• Which side. Idaho puts buttonholes on the right side of women's garments and the left of men's; NMSU's fastener guide gives the same lapping: right over left for women, left over right for men.
• Hems. Idaho's 1983 bulletin says not to make a buttonhole through a hem. That is one archival source; follow the pattern if it says otherwise.

NMSU also advises against choosing a button more than 1/8 in larger or smaller than the pattern calls for, because the buttons will look out of proportion or the buttonholes will need respacing.

2. Zippers: types, the placket and a centered zipper

A zipper closes a seam with two rows of teeth or coils on tape, joined by a slider. The University of Kentucky's zipper fact sheet names three types (University of Kentucky FCS2-842):

The placket is the opening in the seam where the zipper goes. Kentucky makes the opening as long as the teeth, including the top and bottom stops, plus 1 in, and wants at least a 5/8 in seam allowance there; 1 in, it says, makes the zipper easier to put in. Oregon State's zipper sheet adds the space a waistband or facing needs above the zipper: 3/8 in plus a 5/8 in seam at a pants or skirt waist (1 in in all), 1/2 in plus 5/8 in at a neckline (1 1/8 in) (Oregon State 4-H 320-35). Convention

The zipper foot is a narrow presser foot that lets the needle stitch close to the teeth. Singer's accessory guide describes one that attaches to the left or right of the needle, so you can sew either side of the zipper, with grooves underneath for the zipper tape (Singer Accessory User Guide, 2022). Your machine's foot may attach differently; its manual shows how. Product-specific

Preshrinking, and which zipper

• Preshrinking. If the project will be washed hot, a soak of the zipper first costs little; otherwise follow the zipper's package or the pattern.
• Centered or lapped. The pattern's instructions usually decide. This manual teaches the centered zipper first because its two sides are sewn the same way.

A centered zipper, by the baste-and-open method

A centered zipper sits behind a seam with a row of stitching on each side, the two folds meeting over the teeth. The method below follows Oregon State's and Kentucky's sheets, with Singer's guide for the foot.

1. Sew the seam below the opening at the normal stitch length and backstitch at the bottom of the opening.
2. Machine-baste the opening closed on the seamline with the longest stitch. Basting is temporary stitching, long so it is easy to pull out. Press the seam open. Oregon State clips the bobbin thread of the basting every 1 in (2.5 cm) so it pulls out easily later.
3. Mark the topstitching line on the right side with tape or a basted line: 1/4 to 3/8 in from the seam on each side for a centered zipper, by Oregon State's figures.
4. Place the zipper face down on the open seam allowances, the teeth centered on the seam, the stops inside the opening. Pin or baste it to the allowances.
5. Put on the zipper foot and, from the right side, topstitch down one side along your line, across the bottom just below the bottom stop, and up the other side. Kentucky stitches across the bottom 1/8 in beyond the stop and topstitches from the bottom to the top. Keep the needle clear of the metal stop.
6. Pull the thread ends to the inside and tie them, remove the basting and the tape, and press.

When the slider is in the way, stop with the needle down, raise the foot, slide the pull past the needle, lower the foot and go on.

Shortening a zipper. Both Kentucky and Oregon State shorten a conventional zipper from the top or bottom by whipstitching over the teeth several times at the new length with a double thread (Kentucky also allows a machine zigzag), then cutting the excess about 1/2 in below that point.

3. Snaps, hooks and hook-and-loop tape

Every two-part closure has an overlap, the side on top when closed, and an underlap, the side beneath. NMSU's fastener guide places the parts by that (NMSU Guide C-232).

• Snaps are for places with little strain, by NMSU's guide. The ball half goes on the overlap and the socket on the underlap, each stitched 1/8 in from the edge. NMSU notes that no-sew snaps pierce and damage the fabric, so they are worth a test on a scrap first.
• Hooks and eyes suit high-stress places such as waistbands better than snaps, NMSU says. Sewing snaps and hooks by hand is in Everyday mending (hooks, eyes and snaps).
• Snap tape is a woven tape with snaps already set in it, machine-stitched to each side of an opening. The University of Kentucky's fasteners sheet says it is used most on infant and toddler clothing, sportswear and home items (University of Kentucky CT-MMB.029).

Hook-and-loop tape

Hook-and-loop tape has stiff hooks on one strip and soft loops on the other, and closes by pressure. NMSU and Kentucky both describe it as suited to children and to people with limited finger or hand mobility, such as people with arthritis, because it needs no fine finger work. Their placement and care:

• Hook side on the underlap, away from the skin; loop side on the wrong side of the overlap. Both sources.
• Stitch it, do not rely on adhesive. Both sources say the adhesive backing is rarely strong enough alone, and NMSU warns that sewing through it can gum the needle and cause skipped stitches.
• Machine-stitch it at 12 to 15 stitches per inch (about 2.1 to 1.7 mm), NMSU's figure, or sew it by hand.
• Close it when not in use. NMSU and Kentucky both say to keep it closed whenever it is not in use, to protect nearby fabric from the hooks. Convention

Utah State's four-square pillow closes its envelope back with 3 in of hook-and-loop tape, if you want the pillow cover in Your project to close (sewing the project).

4. Casings and elastic

A casing is a fabric tunnel that holds elastic, a cord or a ribbon, at a waist, wrist or ankle. Oregon State's casings sheet describes two kinds (Oregon State 4-H 320-36). A fold-down casing is made by turning the garment's own edge to the inside and stitching it. An applied casing is a separate strip, or bias tape, stitched on, for edges where folding down will not work.

How wide

The tunnel must be wide enough for the elastic to move. Make it at least 1/4 in (6 mm) wider than the elastic, ribbon or drawstring, Oregon State's minimum; a casing that meets it also meets Utah State's smaller minimum of 1/8 in. Utah State adds that the elastic should fit snugly enough in the casing that it does not roll (Utah State, Youth Elastic Waist Skirt). Convention

A fold-down casing

1. Turn the raw edge under 1/4 in (6 mm) and press, as Oregon State does. A line of stitching 1/4 in from the edge first makes the fold easier.
2. Fold again by the casing width and press. Utah State's skirt, for 1 in elastic, presses the top down 1 1/2 in.
3. Stitch along the lower edge close to the fold, leaving an opening to put the elastic in: Utah State leaves 1 1/2 in. Utah State stitches 1/8 in from the folds at the top and bottom; Oregon State's optional top edgestitch sits 1/16 in (1.5 mm) from the edge.
4. Baste the seam allowances flat inside the casing if a seam crosses it. Utah State machine-bastes them at 8 stitches per inch (about 3.2 mm) for 1 1/2 in down from the top, so the bodkin does not catch on them, and removes the basting afterward.

Elastic, threading and fitting

Non-roll elastic has ribs that resist twisting and folding over inside a casing; Oregon State's sheet names it for casings. A bodkin is a blunt needle or clamp that pulls elastic or cord through a tunnel; Utah State and Kentucky use a large safety pin for the same job.

1. Buy at least your measurement. Utah State's skirt buys 1 in elastic at least as long as the waist measurement. For a wrist or ankle sample, use that measurement.
2. Fix a bodkin or safety pin to one end and push it through the casing. Pin the free end to the garment so it does not vanish into the tunnel.
3. Overlap the ends 1 in and pin them with a safety pin, as Utah State does, checking the elastic is not twisted.
4. Try it on. Adjust the overlap until it feels right at the waist (or wrist), then cut off the excess. Bernina's pants leaflet puts it as sewing the elastic at "a comfortable width" (Bernina, Pants Vicky leaflet). Test it
5. Stitch the overlapped ends securely by machine, as Utah State does. Then stitch the casing opening closed.
6. Spread the fullness evenly around the casing. Utah State stitches through the elastic and fabric at each seam, from the right side, to keep the elastic from rolling.

Fit the elastic on the body rather than cutting it to a fixed amount shorter. How much shorter than your waist it ends up depends on the elastic's stretch, the fabric and how firm you want it, which is why the try-on settles it. Test it

5. Drawstrings on anything for a child

A drawstring, in the federal rule's definition, is a non-retractable cord, ribbon or tape that pulls parts of upper outerwear together to close it. The ASTM standard behind the rule names the hazards it addresses: strangulation and vehicular dragging.

What the federal rule says

We checked the rule text in the eCFR on 2026-10-15. 16 CFR Part 1120, the CPSC's substantial product hazard list, names children's upper outerwear in sizes 2T to 16 or the equivalent, with one or more drawstrings, that does not conform to ASTM F 1816-97 (eCFR, 16 CFR Part 1120). A substantial product hazard is the rule's category for products the CPSC can require to be reported and recalled. The rule says girls' and boys' size Large counts as 12 and Extra-Large as 16, and that a garment labelled with a size range is covered if any size in the range is. Section 1120.4 incorporates ASTM F 1816-97, approved June 10, 1997 and published August 1998. The latest eCFR version date for Part 1120 is 2022-12-28, from a 2022 amendment about window coverings; the drawstring text dates from 2011.

The CPSC's business guidance spells out the limits in plain terms (CPSC, Drawstrings in Children's Upper Outerwear):

A bar tack here is what the CPSC describes: stitching through the drawstring and the channel so the string does not slide out (Everyday mending sews a bar tack by hand, hand stitches).

Two editions of the standard

The federal rule cites the 1997 edition, ASTM F 1816-97. ASTM's current edition is F1816-18, reapproved in 2024, written F1816-18(2024) (ASTM F1816-18(2024) scope page). Its scope page covers girls' and boys' upper outerwear such as jackets and sweatshirts worn over other clothing, in sizes 2T to 12 for neck and hood drawstrings and 2T to 16 for waist and bottom drawstrings, the same split as the CPSC guidance. It names strangulation and vehicle dragging as the hazards and exempts fully retractable drawstrings. The full standard is sold by ASTM; we read only its free scope page.

6. See it: Dana's test buttonhole and Marcus's elastic See it

Free sources behind this chapter:

• NMSU Guide C-231, Machine Buttonholes Made Easy: the wrap method, buttonhole shapes, spacing and the test on the same layers.
• Oregon State 4-H, Centered and Lapped Zippers: the baste-and-open method with drawings and topstitching distances.
• Utah State, Youth Elastic Waist Skirt: a fold-down casing and elastic fitted by trying on, start to finish.
• CPSC, Drawstrings in Children's Upper Outerwear: the limits in plain terms, for anyone sewing for a child.

7. Practice: a buttonhole, a zipper and a casing on scrap Practice

Minimum: one test buttonhole that passes its button, one centered zipper, and one elastic casing fitted on your wrist or waist, each labelled. Time: about 2 hours. Materials: scraps of a woven cotton, a small piece of fusible interfacing, one button, a 7 in conventional zipper, the zipper foot and buttonhole foot that came with the machine, about 10 in of 1/2 to 1 in non-roll elastic (or your waist measurement if you test at the waist), a bodkin or large safety pin, pins, a seam gauge and the iron.

1. Size the buttonhole. Measure the button's diameter and thickness and run them through the buttonhole calculator. Note both lengths.
2. Sew the test buttonhole on two layers of scrap with fusible interfacing, at the shorter length. Cut it open between pins and try the button. If it has to be forced, sew a second test at the longer length beside it.
3. Log it on the settings sheet: stitch "buttonhole", the length that passed, fabric and interfacing.
4. Prepare the zipper seam. Cut two scraps about 5 × 10 in. With a 1 in seam allowance, sew 2 in at the bottom at normal length and backstitch, then baste the rest closed and press it open.
5. Sew the centered zipper following the steps: zipper face down, topstitch 1/4 to 3/8 in each side and across the bottom below the stop, then remove the basting. Open and close it ten times.
6. Sew a fold-down casing on a scrap strip long enough to go around your wrist or waist with a few inches to spare: turn under 1/4 in, fold to at least the elastic width plus 1/4 in, stitch the lower edge leaving an opening.
7. Thread the elastic, overlap the ends 1 in with a safety pin, and fit it on your wrist or waist. Adjust, cut, stitch the ends, close the opening.
8. Label all three samples and file them in the sample book.

8. Your sewing Your sewing

9. Check your work Check your work

Criteria

• Was the buttonhole length worked out from the actual button, and tested on the same layers and interfacing?
• Does the button pass without forcing and stay buttoned when the fabric is tugged? Are the ends of the buttonhole uncut?
• Does the zipper open and close smoothly, with no basting left, the folds meeting over the teeth, and the topstitching an even distance from the seam on both sides?
• Is the casing wider than the elastic by at least the amount one of the sources gives, with the elastic lying flat and untwisted?
• Was the elastic length set by trying it on, with the ends overlapped and stitched?
• For anything made for a child: no hood or neck drawstring, and any waist drawstring within the federal limits used as a benchmark?
• Is each sample labelled, and does the buttonhole have a row on the settings sheet?

Worked example

Dana's buttonhole (fictional) meets the buttonhole criteria: sized from her 3/4 in button by two rules (7/8 and 1 in), tested at 7/8 in on two layers with interfacing, the button passes and stays, the bar tacks intact, and the row is on her settings sheet. A buttonhole on another fabric needs its own test. Marcus's elastic (fictional) meets the casing criteria: 1 in non-roll elastic in a casing he checked against both width rules, fitted by trying on to 33 in from the 36 in he bought, overlapped 1 in and stitched. Theo's pair has no drawstring, so the child criterion is met by leaving it out.

Common mistakes

• Sizing a buttonhole from the pattern mark instead of the button, or buying the buttons after the buttonholes are sewn.
• Testing the buttonhole on a single layer without the interfacing the project will have.
• Cutting through the bar tack at the end of a buttonhole. A pin across each end stops the blade.
• Sewing into the metal stop of a zipper, which breaks the needle. Stop the topstitching just short of it.
• Forgetting to baste the zipper opening closed, so the two sides of the seam do not meet over the teeth.
• Cutting elastic to a formula, then finding the waist too tight or too loose. Fit it before cutting.
• A twisted elastic in the casing. Check the overlap before you stitch it.
• Stitching hook-and-loop tape with the hook side against the skin.

What is still unresolved

Samples show the methods work on your machine and scrap; they do not settle the real project. A buttonhole on a garment needs its own test on that fabric, and elastic for a garment is fitted on the person who will wear it (the test sample). Whether any rule applies to something you sew is not something this manual decides; for items you plan to sell, the CPSC is the authority.

10. Knowledge check and scenario

Checklist

• My sample book has a test buttonhole sized from a real button, a centered zipper and a casing with elastic fitted by trying on, each labelled.
• The settings sheet has a row for the buttonhole with the length that passed.
• I know the drawstring limits I will follow for anything I sew for a child.
• I sewed hook-and-loop tape, a lapped or invisible zipper, or an applied casing on scrap. (Go deeper; optional)