Download the spreadsheet and play along at home.
It's been a while since I've done a tutorial and seeing as I use this technique all the time, it's about time I shared it with all of you. This also makes me feel better about the fact that I do not have any updates on my CAL project to post, as my deadline pieces are all keeping me busy.
NOTE: The attached spreadsheet is just a sample and contains measurements that may be useful but which may not meet the standards for some publications. You are welcome to use what I have for your own design purposes but it'll be you who has to ultimately support any patterns written from it, so do your research first.
Excel can be used to help you organize and plot your final pattern. Unfortunately, it can't do all the dirty work, but you can find yourself being a bit more consistent, if you let the program do your calculating. If you plan to submit your patterns for publication, providing a spreadsheet with all your work can be of great help to the tech editor. Doing so, may make logic errors more obvious and allow for faster editing.
For simplicity's sake, we're going to make a simple boat neck top that is identical front and back, has waist shaping, set in style armsceyes and just a little shaping at the neck. Obviously, the more parts you have and the more they vary, the more calculations and measurements you need. Frankly, since I am not in the apparel business and most available resources only offer a limited number of standard measurements, there is a point, for me, when I must make a leap of faith with some measurements. Luckily, knits offer a certain degree of give and take and being off a stitch or two will not generally ruin a piece. For a fairly comprehensive list of measurements and wonderful design instruction, I highly recommend this book.
At this point, don't worry about whether you'll knit in the round or not. It's not even hugely important if you'll work bottom up or top down, though it is usually most intuitive to organize it to flow in the same order that you will knit the piece. For this tutorial, we'll be working bottom up, so all measurements will start at the hip.
The first thing to do is create an area to set your gauge and ease. I like to set up the gauge box to auto calculate the stitches per inch (or per centimeter, if you prefer) out of some larger area. Generally, I do 4 inches. Tthe way that I have it set up, I can change that if necessary.
Make a box for gauge with 3 rows and 3 columns (see below)
Set the number of inches measured and then a single inch below it. I have "4" here but you could measure 6 inches or 3 inches or any other number you like. On the row below, set the calculation to divide the previous row's stitch column by the number of inches. It should look something like this.
I prefer to do this instead of hard coding the division by 4, because there are times I need to change gauge after I've made the spreadsheet. This makes it far more flexible. I can change how many inches I measured and how many stitches I get and the stitches per inch always properly calculates.
Go ahead and set up your Ease as well. I added a vertical ease option, but I don't think this is terribly necessary. You'd want to use this if you tend to work with a lot of negative ease, since doing so will eat up length. For the horizontal ease, I've used a negative number just to show that it works with both positive or negative numbers. You can adjust this at any time and the calculations will update. For ease, I set the amount of ease in inches and then multiply it by the appropriate gauge. This can make it faster to make some calculations.
Expand on your formula
Excel is really great at quickly calculating adjoining cells based on the source cell. It does this by maintaining a relationship between the different variables.
You'll note in the spreadsheet, that I set up each area so that the sizes stay in order, side by side.
If I want to make the waist 8 inches smaller than the chest, for all sizes, I can quickly and easily do this without having to type in a formula for every cell.
To do this, just click the first Waist cell, go to the Formula Bar (you may have to choose to make this toolbar visible) and click "=", click the chest measurement cell (in my case, C7) then type "-8" and press return or tab. The picture above shows the formula as it should be for the Waist for size 34.
The waist becomes 26" based on the formula entered.
Now to expand that to all the other sizes, select the Waist cell for size 34, move your cursor to the lower right corner of that cell until a black plus sign appears. Click and drag across all the other sizes in that row.
All the sizes will automatically update.
Name that cell (Hey, this ones an important one!)
The function I just showed you will be your best friend. Once you have your basic measurement for each size, you'll only write your formulas once, and then expand them to the other cells in the same row. However, there are times when you do not have a different cell value for each size. For instance, you only have one stitch gauge. If you multiply the waist width by the stitch gauge and do the function above, to expand it to the other sizes, Excel will look for the next cell to the right of the gauge, to determine the gauge for that size. Excel doesn't understand that the gauge is a set value and must be applied to all the sizes. You can solve this problem two ways. First, you could set up a gauge box for each size so that when you expand the formula, there is always an accurate value, but that's not ideal. Instead, you can name the cell associated with stitch gauge. When you name it, you are telling excel that whenever you use that cell, it's a fixed element. Don't go changing it when I expand a calculation across the row.
Be careful, though, if you name a cell you don't mean to name, it can throw off your calculations later.
To name a cell, click it.
Go to your toolbars and make sure the Formula bar is visible. This is the same one you used to to type in your calculations. To the far left of the Formula toolbar is a box that tells you the cell's name. Normally it will be a letter and a number, indicating the column and row location of that cell. Click your cursor in that box and type in a name. Click enter. Your cell has been named. I named the stitch gauge "SG" the row gauge "RG" and also named the horizontal and vertical ease.
Now when you can type in "sg" into any formula and have it pull in this value. While creating a formula, you can also click on the cell to have "sg" added to the formula.
If you are trying to name a cell and it doesn't take, make sure you are pressing Return after typing the name. Just clicking somewhere will not apply the change.
Let's start calculating
I generally organize my info in the following way, but you may find a better way that suits you.
In the upper left, I place my slopper measurements. These are the actual body measurement with no ease worked in. Decide how many sizes and what measurements you need and start filling them in. It can be helpful to break up the measurements into meaningful sections. I just used a gray bar to add a little space. You might also want to color code length measurements and width measurements to help you quickly find values when you are working up a formula.
To the right, I create an area to calculate the size of the garment. This will include ease and will be used as the basis for the final pattern. Refer to your schematic drawing and decide what measurements you need to produce each step of the way. I find that I'm actually doing this part and the next part, at the same time. As I'm working out the pattern, I realize I don't know how to get my next value because I haven't provided myself the proper information.
At any time, you can add a new row, by Option (mac) or Alt (pc) clicking the number below where you'd like to add a row.
At the bottom, I have two areas for calculating. The left area is where the raw calculations occur. I am multiplying the stitch or row gauge times various measurements to get the number of stitches or rows I need to work. The raw calculation might tell me I need to cast on 65.2394 stitches. Show me how to do that and I'll buy you a cookie.
To the right, I have the rounded version of the numbers. All I do is indicate that the exact same number should appear there. How do I do that? It's easy. The formula is just an equal sign and then click on the corresponding cell in the Raw Calculations area. Then, we go back to our expanding trick and apply it all the way across the row. Once the row is filled, we can select it and drag down to rows below.
Then, I set the cell so that it shows the number with no decimal points. To do that, I type COMMAND (mac) or CONTROL (pc) + 1. This opens the Format Cell window.
From the NUMBER tab, choose Number and set the decimal places to zero. This will round all the numbers to the closest integer.
You raw numbers are going to default to the "GENERAL" setting which is fine. That setting will just display the numbers for as long as the decimal cares to go or can fit in the spot. You might opt to change this for your own preference.
Just because something is set to round, doesn't mean the numbers will be right. Take a look at the "Actual Pattern" calculations for the size 34. If you pull a calculator out, you'll see the number I have highlighted is actually wrong. The number would rightfully be the
|Stitches after the underarm BO||83|
|Minus double the decreases||8|
The answer is rounding errors. All those decimal places gained us a stitch somewhere. When it comes time to finalize your document, you'll want to overwrite the rounded numbers with the actual numbers. I leave this for last because I often play with the numbers repeatedly, while working out the pattern. Once you update the numbers with actual numbers, you'll want to make sure you set up that area to calculate against itself, not against the raw numbers. The raw numbers are just there for reference.
For instance, in the example above, I'd change the rounded 83 to just 83, the rounded 4, to just 4, and then calculate the total number of stitches with a formula that subtracted double the decreases from the number of live stitches, which would give me the correct value.
It may seem a little overwhelming to follow this tutorial, but I think if you slowly build yourself up to using spreadsheets for your pattern planning, you'll find it really helpful. Feel free to play around with the sample I'm providing you. I don't know that all the calculations are 100%, but you'll get an idea of how to use it. Start small and keep experiementing. You can even manually fill in each section and just use Excel as a means to organize your data. One great way to learn more is to try user Excel to plot an existing pattern that either you or someone else created. You know your gauge and the measurements, so see if you can get the proper cast on, shaping and bind offs.