How to Crochet Half Double Crochet in Rounds with a Straight Seam

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This crochet tutorial will teach you how to crochet a straight seam with half double crochet (hdc) in rounds and the reason for having trouble with this stitch in comparison to other stitches.


After I publish the Straight Seam in Rounds Tutorial, I got hundreds of messages all with the same question: Why does my seam slant after I finished the increase using your method? After doing some digging, I noticed, that it was not every stitch that created this problem. It was only the half double crochet (hdc) that would not create straight seams, but rather have slanted seams.

So, I started to dig deeper and figure out why that is and what you can do about it. I found 2 methods that will help you get the seam straight with hdc. I will teach you both methods in a photo and video tutorial.

Straight Seam with Half double crochet

In case you need some more crochet tips and tricks to have a happier and more relaxed time crocheting, please check out these:

  1. Perfect Straight Seam Every Time
  2. Smooth Edges
  3. Alternative Turning Chain
  4. Hidden Slip Stitch

The Most Important Part of all: WHY you have No Straight Seams with HDC

So first, let’s take a look at the 4 basic crochet stitches. One of the first things to point out is that the half double crochet is a half stitch whereas the single, double and treble crochet stitch are all full stitches (that’s how I see it).

Because of that and the bulk that gets created when crocheting a hdc the “V’s” (below seen as horizontal lines) are not on top of each other row/round by row/round. That creates a shift and makes the seam slanted when crocheting a hdc in rounds. I demonstrate and explain this a bit more detail in the below video.

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Basic crochet stitches (sc, hdc, dc, and tr) drawing
I go these pictures from Craft Yarn Council to represent them visually better and more clearly.
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Why HDC Stitches don’t line up in Rounds

So, here you can see it a bit clearer that the hdc stitches are made in the same shifted over when crocheting “on top” of a stitch from the previous rounds. That creates a shift and you won’t see a straight seam with hdc.

half double crochet in the round

However, to use double crochet as an example, you can clearly see that, as a full stitch, the next stitch “on top” of a dc stitch from a previous round is not shifted over as much and actually gets straightened out when you keep crocheting. The V’s of the stitches (horizontal lines) line up and are parallel from each other which isn’t the case for hdc.

Crochet straight seam with hdc

Proof that HDC Stitches Shift In Rounds

Let’s look at the hdc in a round when it’s laying flat. Look at the spot where the hdc stitch above the hook is. Now, look at the V (horizontal lines) of that stitch. Do you see that it’s shifted over which creates slanting.

hdc in the round

Now, let’s do the same test for a double crochet. Do you see where the dc is above the hook? Now, do you see how the V’s of that stitch align parallel to the V’s below that stitch? That is why a full stitches create straighter seams than half double crochet stitches.

crochet in the round straight seam

So, now that you fundamentally understand how the stitches looks like and how its structure affects whether a seam is straight or not, I will teach you 2 ways how to get a half double crochet seam straight.

How to Crochet a Straight Seam with HDC in Rounds

The below picture show how a typical hdc seam looks like in rounds when you follow a pattern and it tells you to do a ch of 1 or 2 in the beginning of each round. You crochet your typical increases per round until you need to increase in height but not in stitches. You see that you can’t achieve a straight seam with hdc this way. Now, let’s look how you can trick the system.

half double crochet increase in the round

2 Methods to Get Straight Seams with HDC in Rounds

1. Method: Decreases, but a bit bulky

Here, you can see that I got a straighter (but still not perfect) seam with hdc. This is the first method. So, I crocheted a hdc dec at the beginning of each round (not the first round of increases) and then compensated for that stitch at the end of the round by crocheting a hdc inc. That makes the stitch count balance out and creates a shift into the other direction.

Sadly, it creates a bit of a bulk. So you need to decide if that’s worth it for you to get a straight seam with hdc. I also used the hidden slip stitch and did not crochet a ch of 1 or 2 to reduce some of the bulk. The 2nd video below shows this method.

half double crochet in the round -straight seam

2. Method: More Seamless and Straighter Seam

You can also, skip the first stitch after a slip stitch and then add the stitch back after you finish a round. I prefer this method as it looks better and is less bulky. The first video below shows you step by step how to do this method for several rounds.

how to join rounds in crochet without a seam

The Break-Through Moment: Get Straight Seam with HDC Video Tutorial

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Straight Seam with HDC – Another Method

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Straight Seam with HDC

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hdc increase in the round straight seam
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5 Comments

  1. Another GREAT tutorial! Hope you continue to feel better and thanks again for all you’re doing to keep us hooking!

  2. Thank you for this tutorial. I wonder if the decrease stitch would look less bulky if you did it slightly different. I think I would try yarn over insert into first stitch, yarn over insert into next stitch, yarn over pull through two loops, yarn over pull through remaining loops on hook.
    Just a thought that I haven’t tried yet.

  3. Thank you for your clear explanation of how to avoid the slanted seam when crocheting a hdc beanie. It was clearly presented and makes crocheting beanies way less frustrating.

  4. Thank you for this tutorial. I’m working on a project now making pants for my grandbaby using an extended HDC and was just wondering why my seam was slanting. So grateful to see this today. Wow … awesome tutorial. Thank you again.

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