Measurements for the size 26:
Waistband - 30 inches
... hard to measure this, the waistband is curved, laid flat it's 15 inches across the top of the waistband, and 15.5-16 at the bottom of it. I might have done it wrong... I'm not sure how Joyce's 27 measured 27? And my 26's are measuring 30 inches? Hmmmm! I do not think they stretched, even if they did, surely not a full 4 inches!
Front rise - 8.5 inches
Back rise - 13 inches with 6 inch yoke drop
Back pocket dimensions - 6 inch L x 5.5 inch wide
Hip Measurement, laid flat, seam to seam, right above crotch point - 20 inches in front. Back is hard to measure - it's wider. Looks like 24 inches.
Measurement flat, right below crotch point - 10 inches front, 12-13 back
Ankle opening - 11 inches
Comparison to other jeans I own:
I have AG high-waist skinnies, which are super super stretchy (so stretchy it's like wearing pajamas, and yes by end of day they have stretched a tad too much), also in size 26. I'd say they are comparable but the Nikki's of course are designed for a relaxed and loose fit.
I have AG mid/high rise boot cuts that have very little stretch at all, in size 26 and 27; I can't zip either of them at the moment, because of the lack of stretch.
I am also wearing Joe's Jean's, the Niyah skinny, which I'd say is a mid-rise, 10 inch ankle opening, also size 26. I'd say the Nikki's are comparable -- if you have the Joe's, you'll like the Nikki's and can safely order similar size. Of course, the Joe's are not meant to be a relaxed fit. I find the Joe's quite comfortable to wear, not too tight, not too painted on/sausage, just enough stretch, but not so much stretch they bag out by end of day.
Does that help?