diff --git a/.changeset/ninety-queens-walk.md b/.changeset/ninety-queens-walk.md
new file mode 100644
index 000000000..6a447d6da
--- /dev/null
+++ b/.changeset/ninety-queens-walk.md
@@ -0,0 +1,5 @@
+---
+"@delvtech/hyperdrive-js-core": patch
+---
+
+Return bigint instead of number for getLpApy
diff --git a/apps/hyperdrive-trading/src/ui/hyperdrive/hooks/useLpApy.ts b/apps/hyperdrive-trading/src/ui/hyperdrive/hooks/useLpApy.ts
index 6bef7e739..49f896813 100644
--- a/apps/hyperdrive-trading/src/ui/hyperdrive/hooks/useLpApy.ts
+++ b/apps/hyperdrive-trading/src/ui/hyperdrive/hooks/useLpApy.ts
@@ -1,5 +1,6 @@
 import { findHyperdriveConfig } from "@hyperdrive/appconfig";
 import { useQuery } from "@tanstack/react-query";
+import { formatRate } from "src/base/formatRate";
 import { makeQueryKey } from "src/base/makeQueryKey";
 import { isForkChain } from "src/chains/isForkChain";
 import { useAppConfig } from "src/ui/appconfig/useAppConfig";
@@ -15,7 +16,7 @@ export function useLpApy({
   hyperdriveAddress: Address;
   chainId: number;
 }): {
-  lpApy: number | undefined;
+  lpApy: { lpApy: bigint; formatted: string } | undefined;
   lpApyStatus: "error" | "success" | "loading";
 } {
   const { poolInfo: currentPoolInfo } = usePoolInfo({
@@ -49,20 +50,25 @@ export function useLpApy({
                 appConfig.yieldSources[hyperdrive.yieldSource]
                   .historicalRatePeriod,
               );
-          return readHyperdrive.getLpApy({
+          const { lpApy } = await readHyperdrive.getLpApy({
             fromBlock: [31337].includes(chainId)
               ? // local devnets don't have a lot of blocks, so start from the beginning
                 1n
               : // Appconfig tells us how many days to look back for historical rates
                 blockNumber - numBlocksForHistoricalRate,
           });
+
+          return {
+            lpApy,
+            formatted: formatRate(lpApy),
+          };
         }
       : undefined,
     enabled: queryEnabled,
   });
 
   return {
-    lpApy: data?.lpApy,
+    lpApy: data,
     lpApyStatus: status,
   };
 }
diff --git a/apps/hyperdrive-trading/src/ui/hyperdrive/lp/AddLiquidityForm/AddLiquidityForm.tsx b/apps/hyperdrive-trading/src/ui/hyperdrive/lp/AddLiquidityForm/AddLiquidityForm.tsx
index e35849d7c..92207650a 100644
--- a/apps/hyperdrive-trading/src/ui/hyperdrive/lp/AddLiquidityForm/AddLiquidityForm.tsx
+++ b/apps/hyperdrive-trading/src/ui/hyperdrive/lp/AddLiquidityForm/AddLiquidityForm.tsx
@@ -357,10 +357,10 @@ export function AddLiquidityForm({
           <PrimaryStat
             label="LP APY"
             value={
-              isNewPool || lpApy == undefined ? (
+              isNewPool || lpApy === undefined ? (
                 <div className="flex gap-2">✨New✨</div>
               ) : (
-                `${(lpApy * 100).toFixed(2) === "-0.00" ? "0.00" : (lpApy * 100).toFixed(2)}%`
+                `${lpApy.formatted === "-0.00" ? "0.00" : lpApy.formatted}%`
               )
             }
             tooltipContent="The annual percentage yield projection for providing liquidity."
diff --git a/apps/hyperdrive-trading/src/ui/markets/MarketStats/YieldStats.tsx b/apps/hyperdrive-trading/src/ui/markets/MarketStats/YieldStats.tsx
index ababf7aed..6ee719a46 100644
--- a/apps/hyperdrive-trading/src/ui/markets/MarketStats/YieldStats.tsx
+++ b/apps/hyperdrive-trading/src/ui/markets/MarketStats/YieldStats.tsx
@@ -67,9 +67,7 @@ export function YieldStats({
                         <span className="flex flex-row">✨New✨</span>
                       ) : (
                         `${
-                          (lpApy * 100).toFixed(2) === "-0.00"
-                            ? "0.00"
-                            : (lpApy * 100).toFixed(2)
+                          lpApy.formatted === "-0.00" ? "0.00" : lpApy.formatted
                         }%`
                       )}{" "}
                     </span>
diff --git a/apps/hyperdrive-trading/src/ui/markets/PoolRow/PoolRow.tsx b/apps/hyperdrive-trading/src/ui/markets/PoolRow/PoolRow.tsx
index 6b5317db3..4cf7761fc 100644
--- a/apps/hyperdrive-trading/src/ui/markets/PoolRow/PoolRow.tsx
+++ b/apps/hyperdrive-trading/src/ui/markets/PoolRow/PoolRow.tsx
@@ -208,15 +208,13 @@ export function PoolRow({
             isLoading={lpApyStatus === "loading"}
             isNew={isLpApyNew}
             value={
-              // TODO: Fix useLpApy to have the same interface as
-              // useYieldSourceRate and useFixedRate
               lpApy && !isLpApyNew ? (
                 <RewardsTooltip
                   positionType="lp"
                   chainId={hyperdrive.chainId}
                   hyperdriveAddress={hyperdrive.address}
                 >
-                  <PercentLabel value={`${(lpApy * 100).toFixed(2)}`} />
+                  <PercentLabel value={`${lpApy.formatted}`} />
                 </RewardsTooltip>
               ) : (
                 "-"
diff --git a/packages/hyperdrive-js-core/src/hyperdrive/base/ReadHyperdrive.ts b/packages/hyperdrive-js-core/src/hyperdrive/base/ReadHyperdrive.ts
index caba8d8b8..2fd3fd1d8 100644
--- a/packages/hyperdrive-js-core/src/hyperdrive/base/ReadHyperdrive.ts
+++ b/packages/hyperdrive-js-core/src/hyperdrive/base/ReadHyperdrive.ts
@@ -664,7 +664,7 @@ export class ReadHyperdrive extends ReadModel {
   }: {
     fromBlock: bigint;
     options?: ContractReadOptions;
-  }): Promise<{ lpApy: number }> {
+  }): Promise<{ lpApy: bigint }> {
     // If the 24 hour rate doesn't exist, assume the pool was initialized less
     // than 24 hours before and try to get the all-time rate until toBlock
     const { blockNumber: initializationBlock } =
@@ -695,7 +695,7 @@ export class ReadHyperdrive extends ReadModel {
         endPrice: currentLpSharePrice,
         timeFrame,
       }),
-    ).toNumber();
+    ).bigint;
 
     return { lpApy };
   }