Call of Cthulhu 7e Sanity Rules and Sanity Checks Guide

Introduction

Sanity is the rule that makes Call of Cthulhu feel like Call of Cthulhu. This guide covers the whole table procedure: when a Keeper should call for a Sanity check, who rolls, how to read loss notation, what failure and fumbles do, and which thresholds send the game into an insanity procedure. It ends with a record-keeping method that stops those thresholds from slipping past unnoticed.

Hot Take

Most Sanity mistakes have nothing to do with dice. Groups treat the result as a private subtraction that nobody needs to remember. If the table cannot say what caused the loss, when it happened, and whether it crossed a threshold, SAN stops driving the story and becomes a number that quietly gets smaller.

The other common mistake is calling for the roll at the wrong moment. A wet footprint is atmosphere. Realizing it belongs to someone who has been dead for a week is the moment to roll. Charge SAN for entering every creepy room and players go numb; save it for the turns that change what the investigator believes, and they lean forward.

The SAN Rules at a Glance

Call of Cthulhu 7e uses Sanity points, or SAN, to measure how well an investigator withstands traumatic and impossible experiences. A Sanity roll is a percentile roll against current SAN. The Keeper calls for one when an investigator directly faces a meaningful source of horror or disturbance.

The core loop is compact:

1. Describe the unsettling experience.
2. Name the SAN loss notation for that source.
3. Roll equal to or below current SAN.
4. Apply the appropriate loss.
5. Narrate a brief involuntary response after a failure.
6. Check whether the loss triggers a temporary, indefinite, or permanent insanity rule.

The Sanity System hub explains what SAN represents and where the wider rules fit. This guide stays on the table procedure: when the dice belong on the table, and how to resolve the numbers without losing the scene.

Track Three Related Values

SAN is easy to misread because the character sheet holds three numbers that influence one another but do not do the same job.

An investigator with POW 55 begins with 55 current SAN. With no Cthulhu Mythos knowledge, their maximum is 99. If they later gain 7% Cthulhu Mythos, their maximum becomes 92, and they can recover current SAN only up to 92, even if they once had a higher score.

The arithmetic is simple:

Maximum SAN = 99 - current Cthulhu Mythos skill

Update maximum SAN when the Mythos skill changes, not later when recovery is attempted. The maximum Sanity guide and the Cthulhu Mythos skill guide cover that dangerous knowledge track in detail.

Starting SAN Is Not Maximum SAN

Starting SAN comes from POW. Maximum SAN begins at 99. A character with high POW begins with a larger reserve than a character with low POW, but POW does not set a special maximum. The distinction matters most during advancement and recovery, where a player can easily mistake their starting score for the ceiling.

For character creation context, see the characteristics guide. Keep the SAN bookkeeping on the investigator sheet, where everyone can see current and maximum values separately.

Read SAN Loss Notation Correctly

Published scenarios write Sanity loss as two values separated by a slash. The left value is the loss on a successful Sanity roll. The right value is the loss on a failed roll.

The slash is not a choice. The die result decides which side applies, and the loss belongs to the source of horror, not to the investigator's personality or the Keeper's mood. If the scenario has established SAN 0/1D3, a success costs 0 and a normal failure costs 1D3.

For scale, the Keeper Rulebook's own examples run from 0/1D2 for stumbling on a mangled animal carcass, through 0/1D6 for seeing a ghoul, up to 1D10/1D100 for seeing Great Cthulhu. Use published values where they exist and pitch your own somewhere sensible on that range.

Original Example: The Wrong Voice on the Telephone

Ellis has 47 current SAN. In a dark hotel lobby, the disconnected telephone rings. When Ellis answers, they hear their own voice calmly describing something that has not happened yet. The Keeper assigns SAN 1/1D4.

Ellis rolls 22, succeeds, and loses 1 SAN: even a steady investigator cannot entirely dismiss that call. If Ellis instead rolls 68, they fail and lose 1D4 SAN. The event was frightening either way. The roll decides how much of it gets past the investigator's defenses.

How Sanity Checks Work

A Sanity check has two jobs. Mechanically, it decides whether SAN is lost, triggers a brief involuntary response on failure, and sometimes opens the way to temporary or indefinite insanity. At the table, it marks the point where a revelation becomes personal. The group may have suspected the old chapel was dangerous. The check comes when a trusted parishioner speaks in a dead child's voice, or when the mural answers a question no painted wall should understand.

That second job is why timing matters. Players know the dice acknowledge that their investigator has been affected. Keepers gain a pacing lever that turns a clue, a witness, or a location into a decision instead of a flat piece of exposition.

When to Call for a Sanity Check

Call for a check when an investigator is caught up in a source of horror and the moment is significant enough to shake their composure. That can be Mythos horror, but the Keeper Rulebook's example costs also include mundane events such as finding a corpse or witnessing a friend's violent death.

Good triggers usually share at least two of these qualities:

These original scene patterns make strong check moments:

• An investigator recognizes their own handwriting in a journal dated decades before their birth.
• A trusted doctor calmly identifies a patient's impossible anatomy and then asks the group to help conceal it.
• A warehouse door opens onto the shoreline even though the building is miles inland.
• The group learns that the missing person they have been chasing arranged their own disappearance to protect the town from what they found.
• A companion's ordinary photograph changes only when held near a certain artifact.

In each case, the check belongs to the realization. Use a SAN loss that fits the scenario and tone, then let the information stay useful even if the roll goes badly.

Ordinary horror deserves restraint. The event should matter to the campaign rather than merely look striking. A random unpleasant detail every session trains the table to wait for the next subtraction. If a scene touches a player's boundary, do not answer that with a smaller SAN loss. Change or fade the content. Safety practices protect the players; SAN rules challenge the fictional people they portray.

When Not to Call for One

Not every ominous description needs a check. Do not call for one simply because:

• the location is dark, abandoned, or described as creepy;
• a player failed a skill roll;
• the group has already absorbed the same immediate revelation;
• a character made a bad tactical choice;
• the Keeper wants to force a reaction to a clue;
• the scene is unpleasant but carries no emotional weight for the investigator.

A failed Library Use roll may cost time or leave a search incomplete. It is not a SAN event. A locked cellar is an obstacle. A cellar that visibly contains the investigator's childhood bedroom is a possible Sanity check. What separates them is whether reality has broken its contract with the character, not how much description the Keeper piles on.

Do not gate required clues behind SAN. Investigators may lose SAN for learning a necessary truth, but a failed check should not erase the truth. Let them see the evidence and make the cost something else: attention drawn, a moment of lost control, a damaged relationship, a harder exit, or a step closer to a threshold. When failure removes the only clue, horror turns into a dead end. The same principle runs through the skills guide: rolls resolve a live uncertainty, they do not stop the investigation.

Who Makes the Roll

Each player whose investigator experiences the source of horror rolls. Visibility, distance, prior knowledge, and the exact fiction decide who that is.

Keep the ruling plain. "You can all see the figure in the mirror; everyone roll" is enough. If only one investigator has access to the disturbing evidence, give the rest of the group something active to do while it resolves: secure the door, question a witness, prepare an exit, or decide whether to look.

When the party is split, do not make an absent player roll because someone else found something. Resolve the check with the investigator who is there, then let the group deal with the social and practical fallout when they reunite. Being present keeps its value, and remote SAN loss does not become background noise.

Frame the Check Before the Dice

A well-framed check gives the players four things:

1. Perception: what the investigator directly notices.
2. Meaning: what makes it frightening or impossible.
3. Mechanic: which SAN loss notation applies.
4. Immediate stakes: what a brief reaction could complicate right now.

For example: "As the lantern swings back, you see the missing watchmaker standing at the end of the hall. His clothes are dry despite the flood, and the brass face of his pocket watch is where his face should be. This is SAN 0/1D4. The stairwell is behind you, but the innkeeper is still asleep in the next room."

The description explains why the check matters without solving the mystery. The stated loss gives players fair mechanical information. The stakes give a failed reaction somewhere to land. Asking for a roll before the table knows what frightened the investigator can work for an ambush, but used often it turns the dice into a warning siren instead of part of the fiction.

Checks During Combat, Research, and Travel

The activity around a check changes the consequence, not the roll.

Combat: the Keeper Rulebook lets a failed check dictate the investigator's action for that combat round, such as lashing out, squeezing a trigger, or ducking behind someone else. Keep it immediate and legible. It might expose them or waste an opening, but it should not quietly rewrite the whole fight.

Research: the check usually lands when a pattern becomes clear, not with every dusty page. Let the discovery advance the case. A failed response might alert a librarian, damage a fragile document, or leave evidence of the search.

Travel and exploration: a wrong road, a storm, or an empty village builds suspense. The check arrives when the group understands why the road has no way back or why the village is empty.

A Keeper Decision Procedure

Before calling for a check, ask five questions:

1. Did at least one investigator directly experience something disturbing?
2. Does the event violate an expectation or carry real emotional weight?
3. Has the group already rolled for this same immediate encounter?
4. Can the scene continue with the clue intact after a failure?
5. Do I know what a failure changes right now?

If the first two answers are yes and the last three raise no problem, call for the roll. If you cannot name what failure changes, let the scene breathe and wait for a stronger beat. Description, pacing, and choice can build dread long before dice are needed.

Resolve a Sanity Roll Step by Step

Once the check is called, use the same short sequence every time. Consistency keeps rules debates from draining the pressure out of a scene.

1. Establish Direct Exposure

Only the investigators who actually experience the source roll, as described in Who Makes the Roll. Tell the table who is involved.

2. State the Source and Loss

Give enough fiction for the players to understand why the check exists, then state the loss notation. Do not hide the cost until after the roll. The uncertainty is whether the investigator holds together, not whether the Keeper will add an undisclosed penalty.

3. Roll Against Current SAN

Each affected player rolls 1D100. A result equal to or under the investigator's current SAN succeeds. With 47 current SAN, 47 succeeds and 48 fails. Note the current score before any loss is applied, especially when several investigators roll for the same event.

4. Apply the Right Side of the Notation

Use the left side on success and the right side on failure. Subtract the loss from current SAN at once. Roll any loss dice openly enough that the table can track the change.

5. Resolve the Immediate Response

A failed Sanity roll always costs the investigator self-control for a moment. The Keeper chooses a brief involuntary action that fits the scene. The rulebook's examples are jumping in fright and dropping something, crying out, an involuntary movement such as swerving a car, an uncontrolled combat action, or freezing in place. The response should create a concrete next beat, not remove the player from play.

6. Check Consequences Before Moving On

Record the source, the amount lost, and the in-game day. Then check the thresholds described in Thresholds and Time Frames. A large single-source loss and a large daily total use different rules. Do not leave this until the end of the session, when nobody remembers whether the crypt came before or after the hospital.

Success, Failure, and Fumble

The outcome changes both the number and the fiction.

A fumbled Sanity roll takes the maximum loss for that situation or encounter. If the source is SAN 0/1D4, a fumble loses 4 SAN. If the loss is a fixed number, it stays fixed. Do not add an extra arbitrary loss; the fumble is already the worst value the source can inflict.

Success Still Changes the Scene

Success means no loss or a minimal one. It does not mean the event was harmless, and it should not erase the description. Give success a roleplay handle:

• The investigator notices the detail, takes a breath, and records it accurately.
• They keep their voice steady long enough to warn the others.
• They recognize the danger and retreat before panic makes things worse.
• They set aside disbelief just long enough to test a theory.

This matters most for investigators with high current SAN. A success shows resilience in this moment, and the next scene can apply a different kind of pressure, so treat it as a reprieve rather than immunity.

Keep Failure Specific

A failed roll does not make the investigator permanently irrational or hand them to the Keeper for the rest of the scene. The rule covers one moment of lost self-control, and the player decides again once it passes, unless an insanity procedure takes effect. Longer loss of control belongs to a bout of madness, and even during the underlying insanity that follows, the player directs the investigator between bouts.

An involuntary response needs a physical or social consequence. "You are scared" gives the table nothing to play. "You knock the evidence tray into the corridor and the guard hears it" creates an immediate choice. Keep consequences proportionate: a failure in a quiet archive should not become a campaign-ending catastrophe unless the fiction already put that on the table.

Take the watchmaker scene from earlier. The investigator fails and drops the lantern. The flame survives, but its light rolls across the floor toward the sleeping innkeeper's door. Now the group chooses: grab the lantern, flee in darkness, wake the innkeeper, or confront the figure. The failure changed the scene without cancelling the clue or deciding the outcome. Avoid reactions that humiliate a player, cross an established boundary, or wreck a core relationship without a chance to respond.

What You Cannot Do to a Sanity Roll

Sanity rolls deliberately resist the ordinary levers of 7e skill resolution.

• No bonus or penalty dice: the Keeper Rulebook excludes them from Sanity rolls, with one exception: the optional Self-Help key connection rule grants a bonus die.
• No Luck spending: the optional Luck rule cannot be used on a Sanity roll or on the roll for how much SAN is lost.
• No pushing: only skill and characteristic rolls can be pushed. An investigator cannot look at the impossible again, more carefully, for a better result.
• No skill substitution: Psychology, Occult, or a high science skill may color the fiction, but they do not replace a called-for Sanity roll.

These limits protect the genre. A player can prepare, investigate, and choose how to approach danger, but cannot turn every revelation into an ordinary skill challenge. Their real levers are when to look, whom to bring, and what the group does once the truth is out.

Thresholds and Time Frames

The amount lost decides whether the game moves from a momentary reaction into an insanity procedure.

The temporary-insanity threshold is about one source: one terrible sight, one tome, one spell, or one similar event. When 5 or more SAN is lost that way, the Keeper calls for an INT roll. A failed INT roll means the investigator represses the memory and does not go insane. A success means they grasp the full significance of what happened and become temporarily insane for 1D10 hours. It feels backward at first, but the rule treats understanding as the dangerous part.

The daily threshold is cumulative. The Keeper defines the game day, which usually lasts until the investigator reaches a safe place to rest and recover their wits. That can mean surviving until dawn, a cup of tea, or a night's sleep, not necessarily calendar midnight.

The full procedures live in the temporary insanity, indefinite insanity, bouts of madness, and recovering Sanity guides. In the moment, the job is to notice when a threshold has been crossed.

Repeated Encounters and Getting Used to Horror

The encounter is the unit of shock, not the creature. Meeting one ghoul costs 0/1D6; meeting several ghouls at once costs the same. There is no separate charge for every pair of eyes.

Mixed threats can warrant more. The Keeper Rulebook offers an option: the investigator makes one Sanity roll, and on a failure rolls the loss for each monster present and takes the highest result. Its example has an investigator facing three deep ones and Father Dagon, rolling 1D6 three times and 1D10 once, and losing the highest roll. Use this when the threats are different kinds of monster, not to inflate a normal encounter.

Getting Used to the Awfulness

Exposure to a particular kind of Mythos entity also has a cap. Once an investigator has lost as much SAN to that type of monster as its maximum possible loss, they lose no more from seeing it for a reasonable interval. For deep ones at 0/1D6, that cap is 6, however many are seen.

It does not last forever. Players should track SAN lost to each Mythos entity, and at every investigator development phase reduce each of those totals by 1. An investigator who had hit the 6-point cap for deep ones drops to 5, so a failed roll against a deep one can cost them 1 more point.

This is a pacing rule, not permission to make a creature routine scenery. First contact should matter. Later scenes need new stakes: a friend in danger, a changed environment, a new revelation, or a new entity alongside the familiar one.

A Practical Record-Keeping Method

Keep a small SAN log beside the character sheet. Four columns are enough:

Use it to answer four questions fast:

1. What is current SAN after this loss?
2. Was 5 or more lost from this single source?
3. Has one-fifth of current SAN been lost this game day?
4. How much SAN has this investigator already lost to this entity?

For the daily threshold, write down the investigator's SAN at the start of the game day. The Investigator's Handbook suggests marking a line on the sheet at the one-fifth point. If a character starts the day at 50 SAN, losing 10 or more that day crosses it. Do not recalculate from the lower score after several losses.

Keeper Calls That Keep SAN Fair

The Keeper decides when an event warrants a Sanity roll. Good judgment makes the rule hit harder, not more often.

Call for a roll when the event changes the emotional reality of the scene. The first impossible clue, a revelation that contradicts a trusted belief, or a shocking direct encounter all qualify. Routine grim details do not automatically justify a tax on the group.

Make a failed result playable. A shout alerts the night watchman. A dropped key changes the escape route. A flinch gives a witness the chance to slip away. The group still gets the information it needs; the cost changes the route forward.

Separate player boundaries from character consequences. A player can decline a description or use a safety tool without their investigator owing extra SAN. Safety tools protect the people at the table. SAN rules challenge fictional investigators.

Let success mean something. Even when the left side of the notation is zero, a success can show a character holding steady, taking careful notes, or keeping the group moving.

Player Responsibilities During a Check

Players do not decide whether a situation calls for SAN, but they make the rule work by engaging with the fiction around it.

• Ask what your investigator perceives if the scene is unclear.
• Roll against current SAN and record the loss and its source at once.
• Offer a small reaction that fits your investigator when asked.
• Tell the Keeper when a loss might cross the single-source or daily threshold.
• Use a safety tool or speak up if the scene moves into content you do not want to play.
• Keep pursuing the case. Fear is a condition of investigation, not its end.

You do not need to perform distress for the table. One precise choice is enough: "She goes quiet and pockets the photograph," or "He calls the others in before reading another page." That gives the Keeper a human response without turning the scene into a spectacle.

Sanity Rules Checklist

• Call for a check at a meaningful direct encounter or realization, not for every creepy detail, failed skill roll, or repeat look.
• Decide who actually experiences the source before anyone rolls.
• State perception, meaning, SAN loss, and immediate stakes before the dice.
• Roll against current SAN, equal to or below.
• Use the left side of SAN A/B on success and the right side on failure.
• Apply the maximum loss on a fumbled Sanity roll.
• Do not use bonus dice, penalty dice, Luck, or a pushed roll on a Sanity roll.
• Give a failed roll a short, concrete involuntary response, and keep essential clues available on any result.
• Record source, amount, game day, and entity exposure.
• Check 5+ loss from one source, one-fifth loss in a day, and 0 SAN right away.
• Treat a group of the same entity as one encounter; use the highest-roll option only for mixed threats.
• Reduce tracked entity totals by 1 at each development phase.
• Update maximum SAN whenever Cthulhu Mythos skill changes.