Knitting a scarf...help needed

Hi,

I am new to knitting and have just started working on a scarf. Here’s where I am stuck.
The scarf pattern I found has a gauge of 3 sts=1" in pattern stitch and wants me to use a US size 11 needle. The yarn I have and want to use has a gauge of 20 sts=4" in pattern stitch and wants me to use a US size 7 needle. If I use the yarn i have and a US size 7 needle how will this affect my design? Should I try using the yarn I have with a bigger size needle? What will that do?

I will really appreciate any advice.

Thx

Did you try it to see what happens? The yarn may be a little thin for those needles, but you may like the effect.

i tried using the size 7 needles and your right, it was very thin. So Im thinking to use a size 10 needle. My doubt is will this affect the design?
will i need to cast on more stitches to get the length?

Using the same yarn on the 10s? That should work out okay. You cast on sts for width, the length is how long you knit it. You might not need to add more stitches though, try it as written and see how it turns out then.