Call of Cthulhu (7th Edition) Dice Roller Online: Free CoC Dice Generator
Free online dice roller tuned for Call of Cthulhu. Use the main roller to roll any dice combination.
Face cosmic horror with confidence using our free online dice roller for Call of Cthulhu 7th Edition. Chaosium's classic tabletop RPG of mystery and madness uses a percentile system where your Investigators must defy lurking terrors from beyond space and time. Success is a matter of rolling under your character's skill value on a d100, but the odds are often stacked against you. In a game where a single roll can mean the difference between discovering a vital clue and succumbing to a bout of insanity, speed and accuracy are crucial for maintaining narrative tension.
A generic dice roller just won't cut it. Call of Cthulhu's unique mechanics, like bonus and penalty dice, or the multiple levels of success (Regular, Hard, and Extreme), require a specialized tool. This page offers a dedicated CoC dice roller that automates these complex rolls. It calculates success levels instantly, handles the unique 'take the lower/higher tens die' rule, and gets out of your way so you can focus on the investigation and the creeping dread. Forget fumbling with dice, just click and see if your Investigator survives with their sanity intact.
How CoC Dice Work
The core mechanic of Call of Cthulhu is the percentile roll, or d100 check. To perform any action, from firing a pistol to deciphering a forbidden text, you roll to get a number between 1 and 100. This is usually done by rolling two ten sided dice (d10s). One die represents the 'tens' digit (00 to 90) and the other represents the 'units' digit (0 to 9). For a roll to be successful, the result must be less than or equal to your character's corresponding skill value. For example, an Investigator with a Library Use skill of 60% must roll a 60 or less to find the information they seek.
Success is not a simple binary. CoC 7th Edition introduces levels of success that add narrative depth. A 'Regular Success' is any roll at or below your skill value. A 'Hard Success' is a roll at or below half your skill value. An 'Extreme Success' is a roll at or below one fifth of your skill value. A roll of 01 is always a 'Critical Success', the best possible outcome. For our Investigator with Library Use 60, a roll of 31 to 60 is a Regular Success, 16 to 30 is a Hard Success, and 02 to 12 is an Extreme Success. Conversely, a roll of 96 to 100 is typically a Fumble (a critical failure) if the skill value is 50 or more, bringing disastrous consequences.
Favorable or unfavorable conditions are handled with Bonus and Penalty dice. Instead of a simple modifier, you roll an additional 'tens' die. For a Bonus Die, you use the lower of the two tens dice results to form your final number. For a Penalty Die, you use the higher. Imagine your Investigator with a Climb of 30% is trying to scale a crumbling wall in a rainstorm, giving them a penalty die. They roll their units die (e.g., a 4) and two tens dice (e.g., a 20 and a 70). They must use the higher tens die, resulting in a 74, a definite failure.
Using the Roller for CoC
Our ddiceroller.com tool is designed to make your Call of Cthulhu game run smoothly. While you can always use the standard tool to roll a d100, we recommend selecting the dedicated 'Call of Cthulhu 7e' preset from our menu. This unlocks specialized functions that handle the game's unique rules automatically. Simply enter your Investigator's skill value into the 'Target Number' field. Next, select the number of Bonus or Penalty Dice the Keeper has assigned for the roll. With a single click of the 'Roll' button, the tool does all the work.
The results log will display the outcome clearly, showing you the individual dice rolled (including all tens dice for bonus or penalty situations) and the final number. More importantly, it will automatically calculate your level of success: Fumble, Failure, Regular Success, Hard Success, or Extreme Success. This saves valuable time at the table and prevents rules arguments. The roller also includes standard dice like d3, d4, d6, and d8 for calculating firearm damage or the sanity points you will inevitably lose.
Common Rolls
Skill Check (Spot Hidden)
An Investigator with a Spot Hidden of 65% is searching a dusty room for a hidden catch. You enter 65 as the target number and roll 1d100. A result of 65 or less is a success. The roller will specify if a result of 32 or less is a Hard Success, or if a roll of 13 or less is an Extreme Success, providing a much more useful clue.
Combat Roll (.38 Revolver)
Your character, with a Firearms (Handgun) skill of 55%, takes aim at a ghoul. Roll 1d100 against a target of 55. On a success, you hit and then roll for damage. A .38 Revolver deals 1d10 damage, which you can roll using the standard polyhedral dice on our tool. An Extreme Success (11 or less) may allow you to inflict a major wound.
Sanity Loss Roll (SAN)
After witnessing a Deep One, the Keeper declares you lose 1d6 Sanity. There is no target number for this. You simply select a 1d6 from the dice options and roll it. The result is subtracted directly from your current Sanity score. Our roller provides quick access to all common SAN loss dice (d3, d4, d6, d8, d10) for these terrifying moments.
Bonus Die Roll (Fast Talk)
You try to Fast Talk a guard with a skill of 45%, and the Keeper grants you a bonus die because you incorporated the guard's name. You roll a units die and two tens dice. The roller might show a units die of '8' and tens dice of '70' and '30'. It automatically selects the lower '30', giving you a result of 38, a Regular Success. The guard is momentarily convinced.
Frequently Asked Questions
How do you read a d100 roll using two d10s?
A d100 roll uses two d10s of different colors or one marked with tens (00, 10, 20...). One die is the tens digit and one is the units. A roll of '70' and '5' is 75. A roll of '00' on the tens die and '5' on the units die is 5. Crucially, a roll of '00' on the tens and '0' on the units is read as 100, the worst possible percentile result. Our roller automates this numbering to prevent any confusion.
What does it mean to 'push a roll' in Call of Cthulhu?
If you fail a non-combat skill roll, you can choose to 'push' it for a second attempt. You must roleplay a justification for how your character is trying again with more focus or desperation. However, failing a pushed roll carries much more severe consequences defined by the Keeper. For instance, failing a pushed Locksmithing roll might not just fail, but break your tools and alert guards. You can never push a roll that has already been successful, or a combat or Sanity roll.
Is a roll of 01 always a Critical Success?
Yes. In the 7th Edition rules, a roll of 01 is always a Critical Success, regardless of your character's skill level. This represents a moment of pure, improbable luck. It brings an exceptional outcome, like finding the exact solution to a puzzle with a single glance or landing a perfect shot. The specific benefit is determined by the Keeper but should always be significantly better than a standard success. A roll of 100 is likewise always a fumble.
How do multiple bonus or penalty dice work?
If circumstances grant you multiple bonus or penalty dice, they interact simply. First, bonus and penalty dice cancel each other out on a one for one basis. If you have two bonus dice and one penalty die, you are left with one bonus die. If you are left with multiple bonus dice (e.g., two), you roll two extra tens dice and take the lowest single tens die for your result. If you have multiple penalty dice, you roll extra and take the highest.
What dice are used for damage and Sanity loss?
While the d100 is for checks, smaller polyhedral dice (d3, d4, d6, d8, d10) determine variable results, primarily for damage and Sanity loss. A punch deals 1d3 damage, while a shotgun blast can deal 4d6. Sanity (SAN) loss is the game's signature mechanic, with dice rolls representing the mental trauma. A startling event might cost 0/1d3 SAN (0 for a success, 1d3 for a failure), while witnessing an Outer God could inflict 1d20/1d100 SAN loss, potentially driving an Investigator instantly insane.