> ## Documentation Index
> Fetch the complete documentation index at: https://docs.grindxp.app/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# XP & Leveling

> How XP is calculated, how levels are derived, and the math behind multipliers.

XP calculation is deterministic and pure. The calculator lives in `packages/core/src/xp/calculator.ts`.

## Formula

```
final_xp = base_xp × difficulty_multiplier × streak_multiplier × proof_multiplier
```

All multipliers are applied multiplicatively, not additively.

## Difficulty Multipliers

| Difficulty | Multiplier |
| ---------- | ---------- |
| `easy`     | 1.0        |
| `medium`   | 1.5        |
| `hard`     | 2.0        |
| `epic`     | 3.0        |

## Streak Multipliers

| Streak Days | Tier         | Multiplier |
| ----------- | ------------ | ---------- |
| 0–2         | None         | 1.00       |
| 3–6         | Spark        | 1.10       |
| 7–13        | Flame        | 1.20       |
| 14–29       | Blaze        | 1.30       |
| 30–59       | Inferno      | 1.40       |
| 60–99       | Wildfire     | 1.45       |
| 100+        | Eternal Fire | 1.50       |

## Proof Multipliers

| Proof Type       | Multiplier |
| ---------------- | ---------- |
| `self-report`    | 1.00       |
| `timestamp`      | 1.05       |
| `duration`       | 1.10       |
| `process-check`  | 1.20       |
| `file-change`    | 1.20       |
| `git-commit`     | 1.30       |
| `screenshot`     | 1.30       |
| `calendar-match` | 1.30       |
| `ai-verify`      | 1.40       |
| `multi-proof`    | 1.50       |

## Level Curve

Character level uses an exponential curve. Early levels are fast; later levels require significantly more XP:

```typescript theme={null}
levelFromXp(xp: number): number
```

The curve is defined in `xp/constants.ts` as a threshold array. Level 1 requires \~100 XP; each subsequent level requires \~20% more than the previous.

## Skill Level Curve

Skill levels use the same curve shape as character levels but with independent counters. A skill's level reflects only XP earned from quests tagged with that skill.

```typescript theme={null}
skillLevelFromXp(xp: number): number
```

## Using the Calculator

```typescript theme={null}
import { calculateXp, levelFromXp, skillLevelFromXp } from "@grindxp/core/xp";

const xp = calculateXp({
  baseXp: 100,
  difficulty: "hard",
  streakDays: 14,
  proofType: "git-commit",
});
// → 100 × 2.0 × 1.30 × 1.30 = 338

const level = levelFromXp(totalXp);
const skillLevel = skillLevelFromXp(skillXp);
```