The best way to calculate ranges is to determine how many hands they are likely playing in a given situation. The range you assign is a bi-product of who your opponent is, what action they are taking, where they are making that action, and how they might craft that specific range.
The plus sign after a starting hand tells you to include all similar hands that are higher than it. If you see someone write “JJ+”, this is a range strand that says “select pocket Jacks and all pocket pairs above it” so JJ, QQ, KK, and AA. Range strands can also be discussed verbally or shared in forum posts, and there is a common shorthand that players use to quickly talk about ranges. This is typically an ugly line of text, but it can easily be exported from and imported into your poker software of choice.
The range strand is a string of text that lists all of the selected hands. For more information on this, read my complete guide on counting combos & blockers in poker. Keep in mind that combos can be impacted by your hole cards, commonly referred to as blockers.
