USING THE YARN CALCULATOR TABLE
Measure off a number of yards/meters (5 or 10) of yarn, working from the needles. Put a locking pin (I usually tie a loose slip knot over the pin) to mark the end of the measured yarn. Work the rows specified, then measure the remaining yarn to determine yarn used and subtract the remaining yarn from the total measured yarn. If you do not measure enough at the outset, increase and track additional the yards/meters measured as needed. This table is more sophisticated. You may get an error on Row 3 until you have added numbers in both 1 or 2
USING THE YARN REMAINDER FINDER TABLE
The Yarn Remainder Finder is interactive! Click on the box next to the descriptions for 1. original skein weight, 2. remaining skein weight, and 3. skein yardage, and enter the correct numbers. The Yarn Remainder Finder will then do the maths for you! The answers appear in the cell next to “Total yardage (meters) remaining” which has a 0 in it when the table is blank. Hit enter after entering the information for your three values, and voila! Your yardage is calculated (in whichever unit of measurement you entered for your skein yardage).
Find and use the Yarn Remainder Finder right here.
For more about how to read knitting patterns, see Knitting Repeat Language, Using Written Pattern Table Instructions, Gauge, At The Same Time, Measuring / Measure, and Pattern as Established.
For more about patterns in general, see Yarn Consumption Calculator, Action Chart, Yarn Remainder Finder, Grading: Making One Size, Creating Many.