D2R Tool · Free · Offline
D2R Cube Calculator
Enter your rune stash — get the highest rune the cascade reaches and the full gem shopping list.
How rune cubing really works
The Horadric Cube upgrades runes in a fixed chain with fixed tolls: three of a kind plus, from Thul upward, exactly one specific gem. El through Thul cost nothing but runes; the mid ladder (Thul to Lem) eats chipped and flawed gems in a rotating color order — topaz, amethyst, sapphire, ruby, emerald, diamond; and Pul through Gul compress to 2-to-1 with plain gems. Memorizing the gem order is the whole skill, and the calculator removes even that: enter what you own, pick a target, get the cascade.
The expensive question is never "can I" but "should I". Cubing a Pul costs two Puls plus a flawed diamond — if Puls trade above half an Um on your realm, transmuting destroys wealth. The cascade view shows every intermediate rune and gem consumed, so compare the shopping list against trade values before you click transmute. And remember the ceiling: Gul cubes to Vex, and Vex is where the cube stops — everything above drops or trades only.
Gems upgrade 3-to-1 within color and tier on their own track (chipped to flawed to normal to flawless to perfect), which is how mid-rune tolls stay payable from junk drops. For the broader game, see our Diablo 2 Resurrected guide 2026.
Frequently asked questions
Which runes can the cube upgrade?
El through Thul combine 3-to-1 with no gem. Thul through Lem combine 3-to-1 plus a specific chipped or flawed gem. Pul through Gul combine 2-to-1 plus a gem. Vex and above cannot be cubed — they only drop or trade.
Do high rune upgrades work off-ladder?
The Dol-and-up recipes historically required ladder or single-player characters. In D2R ladder-only content is broadly available, but confirm the current season rules before cubing expensive runes.
What gems do I need to save?
Chipped topaz, amethyst, sapphire, ruby, emerald and diamond for the mid runes; flawed topaz, amethyst, sapphire, ruby, emerald and diamond for the high mids; plain topaz, amethyst, sapphire and ruby for Pul through Gul. The calculator lists your exact shopping list.
Is cubing up ever a bad deal?
Often — trade values rarely match cube costs 1:1, and cubing destroys value when the lower runes trade higher separately. This tool shows the cascade so you can compare against trade prices before committing.
Example: cascading to Ist
Input: 6× El, 3× Thul, 1× Chipped Topaz. Target: Ist. Result: cascade reaches Um (not Ist) — shortfall of 1 Um. Gem cost: 3 Chipped Topaz (for Thul→Lem chain). Honest shortfall shown when target unreachable.