Multistranding and estimating gauge

[Think of Winter]

Is there a way to accurately estimate the gauge you'll get with multiple strands?

I love the Misti Alpaca chunky that I used for a scarf recently. It is heaven to knit with. But $14.50 a skein is a rare indulgence for me. Knit Picks has baby alpaca in sport weight. It would cost about $20 per scarf instead of $30 if 2 strands of sport weight = 1 of chunky.

Misti Alpaca chunky
3/5 sts= 1" on US #10

Andean treasure sport
6 sts = 1" on #3 - 5 needles (3.25mm-3.75mm)

Knit picks also has a lace weight baby alpaca. Might that work? Any way to guess?

[zech13_9_goforgold]

The only way I know how to get the guage is to just make a swatch. Why is guage so important to you for a scarf? Couldn't you just kind of guess as you go? For example, I would just buy the sport weight, cast on a certain number of stitches. Then, stretch those stitches out on the needle to see how wide the scarf might be. Just start knitting. If it is too thin or too wide, start over making the necessary adjustments.

[flapjack]

It might work, but I would do a swatch. I personally dislike the look of double stranded in something where texture is integral- like a big, chunky, garter stitch scarf. (I'm not so picky about ribbing, and have no idea what this says about me.)