Common measurement mistakes

Are you making these mistakes without realizing it? Don't worry, you're not the only one.

Converting inches to centimeters, rounding suggestions, and listing measurements are all areas where many designers can make mistakes without even knowing it's a mistake!

INCHES TO CENTIMETERS

It all starts with the gauge. Pattern gauge is measured in a square that is 4 inches (10 cm). But if you use a calculator, 4 inches in real life equals 10.16 cm. Since 10.16 cm is hard to measure (unless you have a magnifying glass) it's rounded to 10 cm for knitting purposes. This is where the errors happen when converting inches to centimeters and vice versa.

CONVERTING USING 2.5 VERSUS 2.54

In real life 1 inch equals 2.54 cm. But in knitting, 1 inch equals 2.5 cm. This means, that all conversions should be made using the correct ratio of 1 inch to 2.5 cm (1:2.5). The .04 cm difference may not seem like a big deal, but it can cause issues when you are grading for larger sizes.

You know when you buy something at the store and the cashier asks, "you want your penny?" Most people say no, because what is a penny going to do? Maybe nothing by itself. But over time those pennies do add up and it could make a difference in the long run. Maybe that's not the best example, but it is another way of looking at how a small difference can add up to a lot in the end.

CONVERSION EXAMPLE

Let's say we have a sweater pattern. Size medium has a finished measurement of 36 inches. Using the real life 2.54 conversion rate (36 x 2.54), it would make it 91.4 cm. Using the knitting 2.5 conversion rate (36 x 2.5), it would make it 90 cm. That's an extra 1.4 cm, which maybe isn't a big deal. But now lets look at size 5XL, which has a finished measurement of 60 inches. Using 2.54 conversion, we get 152.4 cm. And using 2.5 conversion, we get 150 cm. That's 2.4 cm (about 1 inch) of ease that the knitter may not have wanted or taken into consideration when making the pattern.

If you want an accurate pattern that correctly matches your specified finished measurements, it's important to use the correct conversion rate. It's a simple change that will help your patterns become more accurate in the long run.

ROUNDING

Another thing I see, is designers will give centimeter measurements to two decimal places, such as 2.53 cm rather than 2.5 cm. The .03 cm might be a nice idea for the most accurate measurement, but there really isn't a way to see this on a ruler. The same goes for trying to read 3.8 inches on a ruler, it makes more sense to round to 3.75. I would suggest making it a habit of rounding to the nearest quarter (.25) for both inches and centimeters.

HOW TO PROVIDE FINISHED MEASUREMENTS

When it comes to listing the sizes of the finished measurement, you should never provide it in a range of numbers. I've only seen this a handful of times, but it's still worth noting that finished measurements should never be in a range per size. You can provide the "To Fit" measurements and provide a line that suggests how much ease is recommended. Here are some examples on how you could list sizes:

Finished Bust Measurement: 36 (40, 44, 48) inches

To Fit Bust: 32-36 (36-40, 40-44, 44-48) inches

or,

Finished Bust Measurement: 36 (40, 44, 48) inches

To Fit Bust: 32 (36, 38, 42) inches

Suggested Ease: 2-4 inches

but never,

Finished Measurements: 32-36 (36-40, 40-44, 44-48) inches

QUESTION & ANSWER

Q - What's the best way to convert a large range of numbers, since a calculator wont help?

A - Use a spreadsheet! Enter your numbers in inches first in a row in google spreadsheets. In the next line down, enter the formula to convert to centimeters.

If your inch measurement is in cell D3 for example, enter in the cell below: =D3*2.5

Or if you are doing centimeters to inches, enter: =D3/2.5

Q - Do I need to go back into all my published patterns and fix the conversion?

A - No. If you have a few patterns, it might be easy enough to update them all. But designers make updates and changes to their writing styles and formats all the time. Start making these changes on your next and future patterns.

Q - What if I don't want to make this change?

A - Well, that's up to you. But for highest accuracy and success, I strongly encourage you follow the correct conversion rate.

Q - How do I convert inches to centimeters and vice versa, since a calculator is "wrong"?

A - To convert inches to centimeters: inches × 2.5 = centimeters: 26in × 2.5cm = 65 cm

To convert centimeters to inches: centimeters ÷ 2.5 = inches: 65cm ÷ 2.5 = 26in

Have another question? Let me know!

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