Pixel art you can wrap around yourself.

How this is worked out

Gauge tells you how many stitches and rows fit into a measured square. Scale that up to the size you want and you have your stitch count:

stitches across = finished width ÷ gauge width × gauge stitches
rows down = finished height ÷ gauge height × gauge rows

Yardage is the part nobody can tell you exactly, because it depends on your yarn, your hook and how tightly you work. There are two honest ways to get at it.

Weigh a swatch — the accurate one

Work a swatch, note how much yarn it ate, and scale by area. A 4 × 4 in swatch that used 17 yd works out at about 1.1 yd per square inch, so a 48 × 48 in blanket needs roughly 2,450 yd. This is the method worth trusting, because it measures your hands rather than an average.

If you would rather not unravel the swatch, weigh it instead: divide the swatch weight by the ball weight, then multiply by the yards on the ball label.

Estimate from yarn weight — the quick one

Every yarn weight uses a fairly predictable amount per stitch, and taller stitches eat more than short ones. The estimate here uses those averages. Treat it as a shopping guide, not a promise — it can be out by 15% either way, which is exactly why the safety margin is there.

Always buy the same dye lot

Running out three rows from the end and finding the new skein is a slightly different shade is the worst outcome here, and it is the one the safety margin is really protecting you from. Ten percent is sensible. Twenty if the yarn is being discontinued.