diff --git a/api/app/btcpay_routes.py b/api/app/btcpay_routes.py
index 985644b..eefeaeb 100644
--- a/api/app/btcpay_routes.py
+++ b/api/app/btcpay_routes.py
@@ -198,8 +198,17 @@ def _after_expiration(invoice: Invoice) -> bool:
     return detected_at > expires_at
 
 
+# Wownero uses 11 decimal places (atomic unit = 10^-11 WOW), NOT 12 like
+# Monero. Forked from xmrcheckout and MUST be corrected wherever the constant
+# appears. Using 10^12 here broke payment detection — required_atomic came
+# out 10× larger than what wallet-rpc actually reports on the subaddress, so
+# is_paid never flipped and invoices stayed pending forever.
+WOW_ATOMIC_UNITS = Decimal("100000000000")  # 10^11
+WOW_ATOMIC_QUANTIZE = Decimal("0.00000000001")  # 11 decimal places
+
+
 def _xmr_to_atomic(amount: Decimal) -> int:
-    quantized = (Decimal(amount) * Decimal("1000000000000")).to_integral_value(
+    quantized = (Decimal(amount) * WOW_ATOMIC_UNITS).to_integral_value(
         rounding=ROUND_DOWN
     )
     return int(quantized)
@@ -218,15 +227,15 @@ def _btcpay_amount_currency(invoice: Invoice) -> tuple[str, str, dict[str, Any]]
 
 def _format_xmr_fixed(value: Decimal) -> str:
     """Format WOW amount with trailing zeros stripped."""
-    formatted = f"{value.quantize(Decimal('0.000000000001')):.12f}"
+    formatted = f"{value.quantize(WOW_ATOMIC_QUANTIZE):.11f}"
     if "." in formatted:
         formatted = formatted.rstrip("0").rstrip(".")
     return formatted
 
 
 def _atomic_to_xmr(value: int) -> Decimal:
-    return (Decimal(value) / Decimal("1000000000000")).quantize(
-        Decimal("0.000000000001"), rounding=ROUND_DOWN
+    return (Decimal(value) / WOW_ATOMIC_UNITS).quantize(
+        WOW_ATOMIC_QUANTIZE, rounding=ROUND_DOWN
     )
 
 
diff --git a/api/app/reconciler.py b/api/app/reconciler.py
index 0fea2c8..fd66c0b 100644
--- a/api/app/reconciler.py
+++ b/api/app/reconciler.py
@@ -417,8 +417,16 @@ def _safe_update_reconciler_status(
 
 
 
+# Wownero uses 11 decimal places (atomic unit = 10^-11 WOW), NOT 12 like
+# Monero. Using 10^12 here makes required_atomic 10× larger than actual paid
+# amount, so is_paid never becomes true and invoices stay pending forever
+# even after detection + confirmations. This entire codebase was forked from
+# xmrcheckout and the constant must be corrected wherever it appears.
+WOW_ATOMIC_UNITS = Decimal("100000000000")  # 10^11
+
+
 def _xmr_to_atomic(amount: Decimal) -> int:
-    quantized = (Decimal(amount) * Decimal("1000000000000")).to_integral_value(
+    quantized = (Decimal(amount) * WOW_ATOMIC_UNITS).to_integral_value(
         rounding=ROUND_DOWN
     )
     return int(quantized)
diff --git a/api/app/routes.py b/api/app/routes.py
index 25c6b4a..4ee6633 100644
--- a/api/app/routes.py
+++ b/api/app/routes.py
@@ -302,8 +302,10 @@ def _public_invoice_status_response(
     metadata = invoice.metadata_json or {}
     update: dict[str, Any] = {}
     if invoice.total_paid_atomic is not None:
-        total_paid = (Decimal(invoice.total_paid_atomic) / Decimal("1000000000000")).quantize(
-            Decimal("0.000000000001"), rounding=ROUND_DOWN
+        # Wownero uses 11 decimal places (10^11), NOT 12 like Monero. Using
+        # 10^12 here under-reports amount_paid by a factor of 10.
+        total_paid = (Decimal(invoice.total_paid_atomic) / Decimal("100000000000")).quantize(
+            Decimal("0.00000000001"), rounding=ROUND_DOWN
         )
         update["amount_paid_xmr"] = format_xmr_amount(total_paid)
     btcpay_data = metadata.get("btcpay") if isinstance(metadata, dict) else None