How to Make Underwire Adjustments for the Harriet

Choosing Underwires for the Harriet Bra


I’ve been on a little bit of a Harriet binge lately, in part motivated by a desire to use up a bit of my precious lace stash. While recently sorting through some of my bins, I had my first experience of supplies gone bad–I found a few rusted rings and sliders and elastic that actually crumbled when I pulled it out of a bag. Despite my careful inclusions of silica gel packs in tightly sealed rubber bins, I’ve discovered that “aging stash” isn’t always a good thing!

Anyway, this week I made the pattern in a 32G, and sometimes in the larger cup sizes I like to switch out to a wire with a narrower profile. The narrow wires I have happen to be a bit longer than the “regular” wires around which I drafted the pattern, so that also means I had to make some changes.

I get a lot of questions about substituting wires so today I want to share a few tips on choosing and underwire–and what to do when the wire you want doesn’t fit into the size you choose.

Choosing an Underwire

Harriet was drafted around regular length wires from Bra-makers Supply, and I suggest buying these if you don’t want to be bothered with cutting wires or making adjustments. These wires are a good everyday-wear length for many women, they are very good quality, and were perfect for the kind of coverage I wanted from the Harriet.

If you look at the back of the pattern, there is an underwire chart. This will show you which wire to use for your size:

Underwire chart for the Harriet Bra pattern

The length on the right of this chart will tell you the maximum length your wire can be to fit into the bra channeling. I included this because I know many people will buy their wires from a different source, or perhaps prefer to use a different size or shape of wire. In all these cases, it’s important to measure you wire to ensure it will fit.

Something to note if you are new to bra making: there are no standards to shape and length for sizes in wires. So if you purchase a wire from another shop, even if it is the same size as your suggested wire size, it could have a very different length.

(I’ve also written previously about underwire styles and fitting, if you’d like more tips on wire fitting.)


1. Find your wire size

First find the wire length in your chart. For example, I’m making a 32G and the recommended wire length is 11 3/4″.

Harriet Bra underwire length chart

2. Measure the length of your preferred wire

Trace the inside of your preferred wire from tip to tip.

Tracing an underwire to measure its length

Now measure the line with a measuring tape. I suggest doing it twice to make sure you are getting a correct measurement, since measuring tape can be finicky. I like to use one of my fave measuring tools, the Curve Runner–this thing is genius for measuring curves on a sewing pattern!

Measuring an underwire length

3. add some length for wire play

Finally, add 1/2″ or 15mm to that measurement–this is how long your channeling seam needs to be in order to fit your preferred wire.

Adding Underwire Length

The extra 1/2″ is for wire play, which allows the wire to move a little bit during wear. Otherwise, the wire will cause some stress and possibly tear the channeling.

My new wire length is 12 1/4″ which is 1/2″ longer than the recommended length for the 32G.


If your new wire seam length is longer than the wire length in the pattern chart, add the extra length to the pattern itself OR cut the wires to the proper length. In my example of the 32G, I’d need to add 1/2″ in length or cut 1/2″ off the wires.

You can add length to the underarm or the front (or both). This will depend on your preference in fitting, but if it’s a small amount I tend to make the change at the sides. To change at the underarm, add the length to outer cup and the wire seam on the outer cradle.

Lengthen underwire adjustment for Harriet bra

Once you lengthen those areas, smooth the line from strap all the way to the back. As demonstrated in the bottom illustration, line up the outer cup, outer frame and band along their stitching lines and true this line.

To change the front:

Lengthen underwire adjustment for Harriet bra

The other option is to cut your wires. You can cut just the front or just the side or both.

Cutting wires is my preferred method. It’s incredibly easy–takes less than 30 seconds! If you plan to make this pattern more than once, I highly recommend you get yourself some cutters. I use these Knipex mini bolt-cutters (they cut through every wire like butter) and 1/16″ heat shrink tubing to cover the cut tip. (Both will last you forever.)

5. Adjust for a shorter Wire

If your new wire length is shorter than the length in the wire chart, usually you can cut the pattern as is. No adjustments needed!

However, if the difference is more than 1/2″, I recommend changing the pattern by lowering the bridge and the seam at the underarm a bit. Otherwise the bra’s edges are going to fold over your wire (it’s really annoying to wear, trust me!). To lower the seam, make the exact opposite alterations as illustrated above–take out length on all the same pieces and smooth the edges.

On combining sizes

One of the questions I’m often asked is along these lines: I want to use 34F in the cup, but need a wire that fits 34E. Should I cut a 34E size in the cradle and band and adjust the 34F cup to it?

This is possible, but in my experience adjusting a larger cup to a smaller cradle can have unintended fit issues and run into wrinkling in odd places. Part of this is because you end up with a different cradle width as well as length. I recommend the above alterations before messing with franken-sizing. 🙂

a note on plunge wires

The only wires I don’t recommend for the Harriet are plunge-style wires. These wires have a very short and splayed front “arm”. Adapting the pattern for these would require significantly changes to the front and sides. This changes the bra’s silhouette but more importantly you’ll lose some of the pattern’s support in the front.  (If you really want to play with plunge wires, cups with a vertical dart or seam/s work really well with plunging styles, and there are also plunge-specific patterns!)

I hope this post clarified how to substitute wires. (And convinced you that wire cutters are awesome.) Please feel free to ask any questions in the comments!

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