The great thing about sewing is that we are all designers and we are all able to get clothes that fit us well and make us look and feel even better.

But yet many people just sew up the patterns straight out of the envelope (or printer, as may be the case) with out enjoying the possibilities for individual fitting. Some may not do it, because they don’t know how.

SO I thought I would do a series on fitting and altering different kinds of t-shirt.

While there are many ways to fit garment and almost as many books instructing how to, most of them merely talk about fitting woven fabric garments. And while I’m a big fan of tissue fitting, it just will not work with a pattern with no or even negative ease. So here is my tried and true way of fitting t-shirts.

First I’ll talk about the Full Bust Alteration, since it is an alteration which has an enormous impact on the over all fit of the t-shirt.

Most patterns companies (MariaDenmark, and Onion included) draft for a B-cup bust. I am not big busted (I wear a C cup bra), but even I have to do a FBA on my top patterns if I want them to fit great on my shoulders and back. I might measure 90 cm (which would put me in a size S) around the bust. But in reality my back and shoulders have the width of the size XS – the extra cm are “used up” by the bust, which means that a S will be too big around the shoulders and back, and will probably not fit properly over my bust.

These pictures (of the same pattern – one made in a standard size S and one made in XS with a FBA (+ a bit added to the side seams) show it well, I think (click to enlarge).


To determine which size to sew, I take my High (or Upper) bust measurement. Here is a nice article about taking measurements and this excerpt from the Palmer Pletch book also shows (and tells) about the difference between full bust and high bust.

My high bust is 84 cm – which puts me in the XS size.

I started by tracing the pattern of the front piece on to tissue paper, this will make it so much easier to handle doing cutting and re-taping.

{I traced the pattern on to tissue paper – the broken lines marks the seam allowances}

Then it’s time to determine where on the pattern the apex of the bust is (we need it for the next step). In woven shirts this is a lot easier, mainly because I know the measurements for the pattern apex, or can try the tissue on, but with the stretch in the knit fabric, this wont work. So I’ve done this totally non-scientificly by trying on a bunch of different t-shirts, pinning where the apex was when I wore them, fold them in half and measure from the Centre Front. Then I have come to the conclusion that for me it works if I go about 2.5 cm (1″) down from the under arm and find a point that is 3/8 in from centre front. This might work for you too.

{Determining apex point}

Now I draw the lines which are going to work as guides while I add more room to the bust:

{The guide lines}

Line 1 goes straight down from the apex and then from the apex into the armhole – to a point about 1/3 of the way up from the underarm.

Line 2 goes from apex to the side seam (I don’t know how far down it should go – I just imagine where my dart would be).

Line 3 is placed on the centre front side of line 1, perpendicular to line 1. I like to put it just above the waist line.

Now it’s time for the paper scissors: Cut line 1 until the arm hole (you do not want to cut into the seam allowance!) and cut line 2 from the seam allowance and until just before the apex.

{Cut line 1 and 2}

Anchor the pattern piece with pins – I use a cardboard cutting board to pin in to (and align the centre Front line with the line on the board), but you could also use a folded out card board box or an ironing board.

To determine how much room to add to the front piece (i.e. how much to spread the paper apart), I calculate like this (again, this is not scientific, but it works): The size I’ve cut is meant for a 84 cm bust. My bust is 89 cm – so I need 5 extra cm. Since the front piece represents half of the front, I’ll round down to 2 cm – to count the stretch in (5 divided by 2 is 2.5).

I add this by spreading line 1, making sure to keep the two edges of it completely parallel. This makes line 2 spread open (as to form a dart) and also creates a small fold in the arm hole seam allowance. And it’ll make the hem uneven. We’ll deal with the hem and the dart in a minute, and we’ll just tape down the seam allowance fold. It’ll be fine.

{spreading line 1 – and anchoring it with pins}

To make the hem even again, I cut line 3, and slide the bottom section of the centre front side down until the hem is even again (that’s why I like to do it above the waist line, it’s more lines to align with). Remember to anchor it well.

Now I’ll fill in the gaps with new tissue. Just slide pieces in and tape from the top.

{Adding tissue – except to line 2}

I don’t add tissue to the dart formed by line 2, and here is why. I don’t want my t-shirts to have darts – and I don’t mind the little drag lines that you can see in the picture of the striped shirt. Now. If you have made a very big FBA, you might want the dart, and in that case – leave it there. Fill it out with tissue, mark it on your fabric and sew the darts before you sew the side seams.

I do this: I simply close line 2, ignore the little bump it creates (I just tape over it) and let the dart move to a centre front swing.I don’t add tissue to the centre front (all though I could) but just know that it’s there. I also don’t sew the centre front dart!! (that would be weird!)

{I will place the pattern on the fabric as I had filled until centre front with tissue}

When I then cut my fabric, I pretend the tissue at centre front is there (and continues the centre front line). This also adds fabric to my centre front waist, which is good for me, as I need more fabric around my tummy fluff.

That’s it – that’s all there is to it. It’s much faster and easier to do than it looks – and it makes a lot of difference. Not only to woven fabric garments, but also to knit fabric garments!

Give it a try!












19 thoughts on “FIT(TING) TO A TEE (the FBA)

  1. BeccaA

    Thank you for this very clear explanation. The illustrations are very helpful. I have downloaded the pattern. When I get my printer to cooperate I will print it out and try it.

  2. Lene

    That is the most useful tutorial for knit fabrics I have seen in a long time. Thank you so much. My t-shirts never fit well but I couldn’t figure out how to make a FBA without also creating a dart. I can’t wait to try out your method.

  3. Jennifer

    Thank you for posting these instructions. They will be very helpful when I make my next shirt.

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  6. kerri

    Thank you so much for the full bust adj. photos and instructions. I have this issue and it has kept me from sewing for myself. I will have to give it a try with a pattern i already own, but your t pattern looks cute and i Love the Christmas dress! Saw you on Pattern Review! Kerri

  7. Kim

    Hi! I was so excited to discover your free T-shirt pattern on Craftsy, and the FBA tutorial here is a huge bonus. Question: if you’re full busted but small waisted, is there a good way to keep the T-shirt from looking too boxy around the waist?

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  9. Ashlea

    These instructions are great, thank you for taking the time. I keep looking at FBA tutorials, trying to find an answer to my fit issue. I need an fba (e cup), but I don’t need extra width below the bust line. Every FBA tutorial I’ve seen widens the top all the way down to the hem line. Any help or suggestions?

  10. Ashley

    I am taking “Sewing with Knits” on Craftsy and Meg posted this link. i had not heard anything about FBA. I am totally going to try it! I have a tiny frame with a C cup also. It is hard finding shirts that are not too big yet do not squeeze the chest area too much. I have a long torso too. Thanks for this!

    1. mariadenmark Post author

      I’m glad you like it and hope you’ll get great results!
      If you want the t-shirt to fit your long torso as well, just hold up the pattern (matching shoulder lines or bust points) in front of you and establish how much you want to lower the waist. Then cut and spread horizontally just above the waistline (and do it the same amount on the back piece) and add new tissue to the pattern before truing the curves of the side seam.

  11. Lisa

    Thanks for these instructions. I’m curious, doesn’t this now make the waist and hips too big? How does one add a little more ease in the bust area to a pattern where everything else fits well as is?

    1. mariadenmark Post author

      It, does, if you close the dart. (and it does give you a bit more room no matter what) – But you can just redraw the side seam after closing the dart – Just make sure you also check the back side seam – the side seams should have the same length…

      1. Lisa

        Okay, I’m working my way through this as I’m getting ready to make my next tshirt. Where I’m stuck now is matching the side seams. Does one actually ease the front into the back? Or do you redraw the side seam to match the back? Or redraw the back to match the front? The pattern I’m working on has a very fitted waist so there is a lot of curve in the side seam. After the adjustment, the waistline is falling lower on front than on back. If I raise it on the front after doing the adjustment, am I just going back to where I began before the adjustment? Also, what do you do with the section of the side seam above the dart? After the adjustment, it curves back in, which is different than the usual shape of a pattern. Does one leave it or draw the line back outward?

  12. Stefani Laniucha

    Thank you so much for this tutorial I sew for myself and my daughter
    She has a full bust and even using a sewing dummy I have such trouble getting a smooth fit and often having to do alterations before the article is fit for the outside world to see.
    Your simple and down to earth explanations are invaluable I am so glad I found your site.
    Again Thank you

  13. Sharon

    Thank you for your clear and illustrated FBA. I am very happy I found this site. Cheers.

  14. Karrie

    I just tried this out on a knit t-shirt pattern, and it worked wonderfully! I have always had the same problem with those lines across the chest, and had to size up and compromise the fit. My t-shirt fits perfectly in the bust, arms, shoulders, thank you! I did have to take in some of the extra fabric created by the FBA since I didn’t need any extra in the waist/hips but that was not a problem. A perfect tailored t-shirt!

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