Double Letter Research
LL, SS, EE, OO, TT, RR and More — Computed From 74,872 Words

Double Letter Counts — Complete Table

Each row shows the number of database words containing the adjacent double letter pair. Computed by searching for the lowercase two-character substring in each word. A word counts once regardless of how many times the pair appears. QQ appears in 0 words — no standard English word uses adjacent Q-Q.

Methodology: substring search for each two-character pair in every lowercase word. Words containing QQ: 0. Fingerprint: 916f47949b41. Generated: 2026-07-27.

Key Findings — Doubled L Dominates

LL is the most common double letter with 3,350 words — appearing in 4.5% of the database. This reflects LL's central role in English morphology: it appears in -ALL words (BALL, CALL, FALL, HALL, TALL, WALL), -ILL words (BILL, DILL, FILL, GILL, HILL, KILL, MILL, PILL, SILL, TILL, WILL), in -ELLY and -ALLY words, in the -FUL suffix when doubled (SPELLFUL would be hypothetical, but FILLING, BILLING appear), and in hundreds of root words (FOLLOW, YELLOW, FELLOW, VILLAGE, VILLAGE, MILLION, BILLION).

SS is the second most common double with 2,914 words, primarily from plurals of nouns ending in S (BOSS → BOSSES), regular verb forms (MISS → MISSED, MISSES), and root words containing SS (CROSS, DRESS, GLASS, GRASS, PRESS, STRESS, CLASS, BRASS, CLASS).

EE and OO are tied for vowel doubles at 1,598 and 1,590 words respectively. EE appears in words across all registers: SEE, FREE, TREE, AGREE, COFFEE, FIFTEEN, EMPLOYEE. OO appears in BOOK, COOK, FOOD, GOOD, MOON, NOON, POOL, SCHOOL, SOON, TOOTH, WOOD, ZOOM. Both vowel doubles tend to appear in medium-length words averaging 7–8 characters.

ZZ is the rarest common double letter with 186 words — about 0.25% of the database. ZZ words are disproportionately high-scoring in Scrabble: PIZZAZZ (45 pts), JAZZ (32 pts), FIZZ (26 pts), BUZZ (24 pts), JAZZ. The double-Z pattern is valuable for Scrabble players who hold two Z tiles (a rare rack state requiring blanks in the standard single-Z tile set).

Scrabble Implications — Double Letters and Board Strategy

Double Letter Score (DLS) squares are particularly valuable for double-letter words when the high-value letter of the pair lands on the square. Two Z tiles on a Double Letter Score square contributes 2×10 + 10 = 30 points from those two positions alone. Two L tiles on a DLS contribute only 1 + 1 = 2 total points even with the multiplier — LL is common but not high-scoring per tile.

For rack management, knowing that LL and SS are common double-letter patterns encourages holding duplicate L or S tiles if needed to complete words like FILLING, BILLING, CALLING (all with LL) or CROSSING, PRESSING, BLESSING (all with SS). Duplicate tiles are usually avoided in Scrabble strategy because they reduce flexibility, but when they complete a high-probability pattern, they are worth keeping.

The ZZ pattern produces extremely high-scoring words relative to their length. JAZZ (4 letters, 32 pts base) scores 8 points per letter — among the highest points-per-letter ratios in the database. The Scrabble Score Calculator allows verification of any word's base score including double-letter patterns.

Double Letter Patterns Across Word Lengths — Where Doubles Appear Most

Double letters distribute unevenly across word lengths. LL is most common in short words (4-7 letters): BELL, CALL, DOLL, FILL, FULL, GILL, GULL, HALL, HILL, HULL, ILL, JELL, KILL, LULL, MILL, PULL, SELL, TELL, TILL, TOLL, WALL, WELL, WILL, YELL are all under 5 letters. SS clusters in medium words (5-8 letters): CROSS, CLASS, GLASS, GRASS, PRESS, DRESS, BLESS, CHESS, MISS forming the short end and PROGRESS, COMPRESS, SUPPRESS, DISTRESS forming the long end.

TT is unusual because it appears primarily in morphological contexts — specifically in the doubling that occurs before certain suffixes. When a short-vowel root ending in a consonant takes a vowel suffix, the consonant doubles: SET → SETTING, HIT → HITTING, CUT → CUTTING, PUT → PUTTING, GET → GETTING, BIT → BITTING. This morphological rule creates a cluster of TT words in the 7-9 letter range (SETTING=7, HITTING=7, CUTTING=7, GETTING=7, SITTING=7) and explains why TT is the fourth most common double despite T being a relatively common letter overall.

PP follows the same morphological doubling pattern but less productively than TT because fewer common English verbs end in P with a short vowel. TIPPING, TOPPING, STOPPING, CLAPPING, DROPPING, WRAPPING are the main examples — fewer total words than the TT series but still 956 database entries containing PP.

EE appears across a wide length range because it marks a specific vowel sound (the long E sound in FREE, SEE, TREE) rather than a morphological process. EE words tend to be root words rather than inflected forms, giving them a more even distribution across 3-12 letters: BEE (3), TREE (4), CREEK (5), CHEESE (6), FREEDOM (7), EMPLOYEE (8), COMMITTEE (9), DISAGREEMENT (12).

The Scrabble implications of double-letter distribution extend to rack management. If a player holds two L tiles, the high frequency of LL in short words (BALL, BELL, BILL, CALL, CELL, DOLL, FILL, FULL, GULL, HALL, HILL, HULL, KILL, LULL, MALL, MILL, NULL, POLL, PULL, SELL, TALL, TELL, TOLL, WALL, WILL, YELL) offers many 4-5 letter play options. If a player holds two T tiles, the TT pattern is most useful combined with -ING endings for 7-letter bingo plays: holding T, T, I, N, G plus two root consonants enables SETTING, HITTING, GETTING, LETTING, and many more.

Double Letter Distribution — Complete Context

The double letter counts in this research are produced by checking for the presence of each two-character sequence in every database word using Python's in operator: pair.lower() in word. A word containing LL anywhere scores once regardless of how many LL sequences it contains. STILLNESS contains two L pairs in sequence LLLL but is counted once. This counting method follows the word-level granularity consistent with all other database statistics on this site. Fingerprint: 916f47949b41. Generated: 2026-07-27. For reproducibility, the computation is: count = sum(1 for w in words if pair.lower() in w).

Summary Reference — Double Letter Counts at a Glance

Quick reference: LL=3,350, SS=2,914, EE=1,598, OO=1,590, TT=1,420, RR=1,073, PP=956, NN=837, FF=749, MM=734, GG=558, DD=454, BB=446, CC=405, ZZ=186, QQ=0. Total database: 74,872 words. All counts from fingerprint 916f47949b41, 2026-07-27. ZZ words are the most Scrabble-valuable per letter position despite being the second rarest double. LL words are the most numerous and span the widest length range of any double-letter category.