diff --git a/src/arcaea_offline/calculate.py b/src/arcaea_offline/calculate.py
index 30cfc71..38fcf49 100644
--- a/src/arcaea_offline/calculate.py
+++ b/src/arcaea_offline/calculate.py
@@ -1,5 +1,89 @@
-from .models import Score, Calculated
-from typing import List
+from decimal import Decimal
+from math import floor
+from typing import Dict, List
 
-def calculate_b30(calculated_list: List[Calculated]):
-    scores = []
+from .models import Calculated, Chart, Score
+
+
+def calculate_score(chart: Chart, score: Score) -> Calculated:
+    assert chart.song_id == score.song_id
+    assert chart.rating_class == score.rating_class
+
+    single_note_score = 10000000 / Decimal(chart.note)
+    actual_score = (
+        single_note_score * score.pure + single_note_score * Decimal(0.5) * score.far
+    )
+    pure_small = score.score - floor(actual_score)
+
+    constant = Decimal(chart.rating) / 10
+    if score.score >= 10000000:
+        potential = constant + 2
+    elif score.score >= 9800000:
+        potential = constant + 1 + (Decimal(score.score - 9800000) / 200000)
+    else:
+        potential = max(
+            Decimal(0), constant + (Decimal(score.score - 9500000) / 300000)
+        )
+    assert isinstance(potential, Decimal)
+
+    return Calculated(
+        song_id=chart.song_id,
+        rating_class=chart.rating_class,
+        score=score.score,
+        pure=score.pure,
+        far=score.far,
+        lost=score.lost,
+        time=score.time,
+        rating=chart.rating,
+        note=chart.note,
+        pure_small=pure_small,
+        potential=float(potential),
+    )
+
+
+def get_b30_calculated_list(calculated_list: List[Calculated]) -> List[Calculated]:
+    best_scores: Dict[str, Calculated] = {}
+    for calculated in calculated_list:
+        key = f"{calculated.song_id}_{calculated.rating_class}"
+        stored = best_scores.get(key)
+        if stored and stored.score < calculated.score or not stored:
+            best_scores[key] = calculated
+    ret_list = list(best_scores.values())
+    ret_list = sorted(ret_list, key=lambda c: c.potential, reverse=True)[:30]
+    return ret_list
+
+
+def calculate_b30(calculated_list: List[Calculated]) -> Decimal:
+    ptt_list = [Decimal(c.potential) for c in get_b30_calculated_list(calculated_list)]
+    sum_ptt_list = sum(ptt_list)
+    return (sum_ptt_list / len(ptt_list)) if sum_ptt_list else Decimal("0.0")
+
+
+def get_r10_calculated_list(calculated_list: List[Calculated]) -> List[Calculated]:
+    recent_scores: Dict[str, Calculated] = {}
+    for calculated in calculated_list:
+        key = f"{calculated.song_id}_{calculated.rating_class}"
+        stored = recent_scores.get(key)
+        if stored is None or stored.time < calculated.time:
+            recent_scores[key] = calculated
+    ret_list = list(recent_scores.values())
+    ret_list = sorted(ret_list, key=lambda c: c.time, reverse=True)[:10]
+    return ret_list
+
+
+def calculate_r10(calculated_list: List[Calculated]) -> Decimal:
+    ptt_list = [Decimal(c.potential) for c in get_r10_calculated_list(calculated_list)]
+    sum_ptt_list = sum(ptt_list)
+    return (sum_ptt_list / len(ptt_list)) if sum_ptt_list else Decimal("0.0")
+
+
+def calculate_potential(calculated_list: List[Calculated]) -> Decimal:
+    b30_ptt_list = [
+        Decimal(c.potential) for c in get_b30_calculated_list(calculated_list)
+    ]
+    r10_ptt_list = [
+        Decimal(c.potential) for c in get_r10_calculated_list(calculated_list)
+    ]
+    b30_sum = sum(b30_ptt_list) or Decimal("0.0")
+    r10_sum = sum(r10_ptt_list) or Decimal("0.0")
+    return (b30_sum + r10_sum) / (len(b30_ptt_list) + len(r10_ptt_list))