If you don’t have a yarn balance you can determine yards per pound (YPP) or meters per kilogram (MPKG) of a yarn by measuring a known length and extrapolating from its weight. A short length is bound to be too light for most scales to weigh accurately, so the best approach is to wind yourself a tiny little “warp” and weigh that.
Measuring out the yarn
Tie some other yarn onto a warping board, just as if you were putting on a guide string to wind a short little warp. Be sure to use knots rather than wrapping either end around a peg a bunch of times to secure it – you need to know exactly how far apart the two ends are. It doesn’t really matter how long this “warp” is so don’t worry about making it any particular length, just pick a path that’ll be quick and easy to follow.
My intuition tells me that making your “warp” at least a yard long will introduce less error than something shorter, so I default to two passes on my warping board: from the cross to the opposite side, and then back to a different point on the starting side. Leave that measuring string where it is for the time being.
Now use your mystery yarn to follow this path several times, until the whole lot looks like something your scale will be able to measure. Tie off onto the last peg and count the number of ends you’ve got before doing anything else. Don’t add any ties – you don’t want to add any weight at all. Being careful not to include the measuring string, chain your little warp off the board and tie it at both ends so that it can’t come apart (tying the chain itself into a knot doesn’t add any new weight).
Next, measure the guide string from the end of one loop to the end of the other loop, and weigh the little chain. Use inches and ounces if you’re heading for yards per pound, and centimeters and grams if you’re aiming for meters per kilogram.
Calculating YPP or MPKG
THen either math them this was for Imperial….
Length of guide string in inches x number of ends in chain ÷ 36 = Length of chain in yards
Length of chain in yards ÷ weight of warp in ounces x 16 = Yards per pound (YPP)
….or this way for Metric:
Length of guide string in cm x number of ends in chain ÷ 100 = Length of chain in meters
Length of chain in meters ÷ weight of warp in grams x 1000 = Meters per kilogram (MPKG)
Now go forth and calculate, weaving friends!