Why compare these merino yarns?
Sandnes Double Sunday and Knitting for Olive Heavy Merino are both published as 100% merino wool in 50 g balls. That makes them a relevant paper comparison for a merino pattern, but the shared fiber label and package weight do not establish interchangeable yarns or identical fabric.
Their published gauges do not overlap
Sandnes publishes 20–21 stitches per 10 cm for Double Sunday on 3.5–4 mm needles. Knitting for Olive publishes 18 stitches and 30 rows per 10 cm for Heavy Merino on 4.5 mm needles. The manufacturer ranges do not overlap, so reaching a pattern gauge requires a washed swatch and may still produce an unsuitable fabric.
The same ball weight carries different length
Double Sunday contains approximately 108 m per 50 g; Heavy Merino contains 125 m. For an illustrative 1,000 m requirement, Double Sunday needs ten whole balls and Heavy Merino needs eight. This is package arithmetic only: the pattern size, strand arrangement, gauge and swatching allowance determine the quantity to buy.
Keep the published gauge disagreement visible
Sandnes lists Double Sunday at 21–20 stitches per 10 cm in source order, while Mother Knitter lists 21–22. Skeinspan uses the manufacturer’s normalized 20–21 range for comparisons and preserves the retailer conflict in the yarn record. Check the current ball band rather than treating either published range as a guarantee.
Treatment, care and sourcing need separate checks
Sandnes identifies Double Sunday as non-superwash and recommends a separate wool-machine program with flat drying. Knitting for Olive specifies cool hand washing and flat drying for Heavy Merino; its captured product record does not state a treatment. Mother Knitter and Heavenly Yarns provide the dated US retailer evidence linked below. Confirm inventory and care for the yarn purchased.
Specification sources: Sandnes Garn Double Sunday. Knitting for Olive Heavy Merino. Sources and retail evidence are detailed below. These are desk comparisons; no physical testing has been performed.