Klondike: the one-deck classic, measured against its two-deck twin
Klondike is the 52-card game most Americans know simply as Solitaire: seven columns, a draw pile, four foundations. On a site built around a two-deck game, the obvious question is what happens to Klondike when you double it. We can answer that directly, because we played both Klondike and its two-deck form, Solitaire Double, with the same simple program.
On one deck, the program won 42.3% of 10,000 one-card-draw deals (95% range 41.3%–43.3%). On two decks it won 81.5% of 10,000 (80.7%–82.2%). For one deck we also have a ceiling: a planning search that knows the hidden cards proved 76.6% of 1,000 deals winnable (73.9%–79.1%). For two decks we have no ceiling at all.
At a glance: Klondike with one deck and with two
| Measure | Klondike, 1 deck | Solitaire Double, 2 decks |
|---|---|---|
| Simple program won (floor) | 42.3% (41.3–43.3%), 10,000 | 81.5% (80.7–82.2%), 10,000 |
| Planning search, proven winnable | 76.6% (73.9–79.1%), 1,000 | not run |
| Planning search, proven impossible | 2.1% (1.4–3.2%) | not run |
| Planning search, undecided | 21.3% (18.9–23.9%) | not run |
| Published, perfect knowledge | 90.48% (±0.116%) | none published |
| Moves in the program's wins | 126.2 (125.9–126.4) | 268.1 (267.8–268.4) |
| No move among face-up cards at the start | 8.6% (8.1–9.2%) | 2.7% (2.4–3.0%) |
The program never undoes and sees only face-up cards, so its figures are floors. The search sees hidden cards, so its figure is a ceiling no person reaches. The published figure is from Blake and Gent (2026).
What one deck takes away
No twin to fall back on
With 52 cards, each card exists once. If the only red 8 your black 7 can use is under five face-down cards, you wait. In Solitaire Double a second red 8 of each suit exists.
More dead starts
8.6% of one-deck layouts give no move among the seven face-up cards, over three times the two-deck share.
Hidden Aces matter a little
88.0% of one-deck deals had at least one Ace face down (1.6 of 4 on average). The program won 44.5% of deals with no Ace hidden and 41.6% with two or more: a small effect.
But the game is short
About 126 moves per win for the program, against 268 on two decks.
Rules on freecell-two-decks.com
- Deal: 28 cards in seven columns of one to seven, last card face up; 24 in the stock.
- Foundations: four, Ace to King by suit.
- Building: down in alternating colors; ordered runs move together.
- Empty columns: Kings or King-headed runs only.
- Stock: one card at a time, unlimited passes. The draw toggle switches to Turn 3.
- Foundations: a card may come back down if you need it.
Playing the single deck well
Know where each card's only copy is
Keep a rough map of the stock. The program's wins went through it about 2.3 times; each pass is a chance to note where things are.
Uncover the tall columns
Prefer moves that reveal a card in a column with more hidden cards beneath.
Don't rush the middle ranks home
One deck means one landing spot per card. Keep 6s and 7s in play until the opposite color's lower cards are up.
Plan the King before the space
Only Kings fill spaces. Empty a column when one is ready.
Undo is look-ahead
Try a line, see what it turns over, take it back if needed.
Klondike on this site
Free in any modern browser on computer, tablet or phone, no sign-up. Hint, unlimited Undo, Restart, Auto Play, zoom, drag or tap, a count of wins, time and moves, and sound, fullscreen and table color settings.
How we compared them
The freecell-two-decks.com team ran these simulations in September 2026 on this site's own game code.
- Rules read from the code for both games: Turn 1, unlimited passes, Kings-only spaces.
- One program, two tables: the same priority list extended to nine columns and eight foundations for two decks.
- 10,000 numbered deals each, seeds 1–10,000.
- A planning search for one deck only: 1,000 deals, up to 150,000 positions each, knowing hidden cards.
- Published check: Blake and Gent (2026) give 90.48% for one deck, inside our 76.6–97.9% range; they do not cover two decks.
- 95% ranges: Wilson score for rates, normal intervals for averages.
Python 3.11, standard library only. Claude, an AI assistant by Anthropic, helped write and check the code and draft this page; every figure comes from running the code.
Klondike questions
Is Klondike the same as Solitaire?
For most people in the U.S., yes.
Would two decks make it easier?
For our simple program, 81.5% against 42.3%. Try Solitaire Double and see.
How many deals can be won?
At least 76.6% by our search; 90.48% published.
What next?
The three-card draw is on Klondike Turn 3. The site's main game is FreeCell Two Decks. All games are on the games page.
By Admin, freecell-two-decks.com (Forty Media). Research run September 2026.