diff --git a/packages/__tests__/cost/__snapshots__/registrySnapshots.test.ts.snap b/packages/__tests__/cost/__snapshots__/registrySnapshots.test.ts.snap
index ab023ddc00..3686c3aadd 100644
--- a/packages/__tests__/cost/__snapshots__/registrySnapshots.test.ts.snap
+++ b/packages/__tests__/cost/__snapshots__/registrySnapshots.test.ts.snap
@@ -5932,6 +5932,59 @@ exports[`Registry Snapshots endpoint configurations snapshot 1`] = `
       ],
     },
   },
+  "openai/gpt-5.5": {
+    "gpt-5.5:openai": {
+      "context": 1050000,
+      "crossRegion": false,
+      "maxTokens": 128000,
+      "modelId": "gpt-5.5-2026-04-23",
+      "parameters": [
+        "logprobs",
+        "max_completion_tokens",
+        "response_format",
+        "seed",
+        "stop",
+        "temperature",
+        "tool_choice",
+        "tools",
+        "top_p",
+        "verbosity",
+      ],
+      "provider": "openai",
+      "ptbEnabled": false,
+      "regions": [
+        "*",
+      ],
+    },
+    "gpt-5.5:openrouter": {
+      "context": 1050000,
+      "crossRegion": false,
+      "maxTokens": 128000,
+      "modelId": "openai/gpt-5.5",
+      "parameters": [
+        "frequency_penalty",
+        "logit_bias",
+        "logprobs",
+        "max_completion_tokens",
+        "max_tokens",
+        "presence_penalty",
+        "response_format",
+        "seed",
+        "stop",
+        "temperature",
+        "tool_choice",
+        "tools",
+        "top_logprobs",
+        "top_p",
+        "verbosity",
+      ],
+      "provider": "openrouter",
+      "ptbEnabled": false,
+      "regions": [
+        "*",
+      ],
+    },
+  },
   "openai/gpt-image-1": {
     "gpt-image-1.5:openai": {
       "context": 8192,
@@ -7657,6 +7710,10 @@ exports[`Registry Snapshots model coverage snapshot 1`] = `
     "openrouter",
     "openrouter",
   ],
+  "openai/gpt-5.5": [
+    "openai",
+    "openrouter",
+  ],
   "openai/gpt-image-1": [
     "openai",
     "openai",
@@ -9713,6 +9770,37 @@ exports[`Registry Snapshots pricing snapshot 1`] = `
       },
     ],
   },
+  "openai/gpt-5.5": {
+    "openai": [
+      {
+        "cacheMultipliers": {
+          "cachedInput": 0.1,
+        },
+        "input": 0.000005,
+        "output": 0.00003,
+        "threshold": 0,
+        "web_search": 0.01,
+      },
+      {
+        "input": 0.00001,
+        "output": 0.000045,
+        "threshold": 272000,
+      },
+    ],
+    "openrouter": [
+      {
+        "input": 0.000005275,
+        "output": 0.00003165,
+        "threshold": 0,
+        "web_search": 0.01,
+      },
+      {
+        "input": 0.00001055,
+        "output": 0.000047475,
+        "threshold": 272000,
+      },
+    ],
+  },
   "openai/gpt-image-1": {
     "openai": [
       {
@@ -10495,6 +10583,13 @@ exports[`Registry Snapshots verify registry state 1`] = `
         "openrouter",
       ],
     },
+    {
+      "model": "gpt-5.5",
+      "providers": [
+        "openai",
+        "openrouter",
+      ],
+    },
     {
       "model": "gpt-image-1",
       "providers": [
@@ -10910,11 +11005,11 @@ exports[`Registry Snapshots verify registry state 1`] = `
       "provider": "novita",
     },
     {
-      "modelCount": 33,
+      "modelCount": 34,
       "provider": "openai",
     },
     {
-      "modelCount": 71,
+      "modelCount": 72,
       "provider": "openrouter",
     },
     {
@@ -11049,8 +11144,8 @@ exports[`Registry Snapshots verify registry state 1`] = `
     "claude-3.5-haiku:anthropic:*",
   ],
   "totalArchivedConfigs": 0,
-  "totalEndpoints": 329,
-  "totalModelProviderConfigs": 329,
+  "totalEndpoints": 331,
+  "totalModelProviderConfigs": 331,
   "totalModelsWithPtb": 108,
   "totalProviders": 21,
 }
diff --git a/packages/cost/models/authors/openai/gpt-5.5/endpoints.ts b/packages/cost/models/authors/openai/gpt-5.5/endpoints.ts
new file mode 100644
index 0000000000..4445514d24
--- /dev/null
+++ b/packages/cost/models/authors/openai/gpt-5.5/endpoints.ts
@@ -0,0 +1,101 @@
+import { ModelProviderName } from "../../../providers";
+import type { ModelProviderConfig } from "../../../types";
+import { GPT55ModelName } from "./models";
+
+export const endpoints = {
+  "gpt-5.5:openai": {
+    providerModelId: "gpt-5.5-2026-04-23",
+    provider: "openai",
+    author: "openai",
+    pricing: [
+      {
+        threshold: 0,
+        input: 0.0000050, // $5.00 per 1M tokens
+        output: 0.000030, // $30.00 per 1M tokens
+        web_search: 0.01, // $10 per 1000 searches (1:1 USD; 10/1K)
+        cacheMultipliers: {
+          cachedInput: 0.1, // $0.50 per 1M tokens
+        },
+      },
+      {
+        threshold: 272000,
+        input: 0.000010, // $10.00 per 1M tokens (2x for >272K context)
+        output: 0.000045, // $45.00 per 1M tokens (1.5x for >272K context)
+      },
+    ],
+    contextLength: 1_050_000,
+    maxCompletionTokens: 128_000,
+    rateLimits: {
+      rpm: 15000,
+      tpm: 40000000,
+      tpd: 15000000000,
+    },
+    supportedParameters: [
+      "tools",
+      "tool_choice",
+      "seed",
+      "max_completion_tokens",
+      "response_format",
+      "stop",
+      "verbosity",
+      "temperature",
+      "top_p",
+      "logprobs",
+    ],
+    unsupportedParameters: [
+      "presence_penalty",
+      "frequency_penalty",
+      "top_logprobs",
+      "logit_bias",
+      "max_tokens",
+    ],
+    ptbEnabled: false,
+    endpointConfigs: {
+      "*": {},
+    },
+  },
+  "gpt-5.5:openrouter": {
+    provider: "openrouter",
+    author: "openai",
+    providerModelId: "openai/gpt-5.5",
+    pricing: [
+      {
+        threshold: 0,
+        input: 0.000005_275, // $5.275/1M - worst-case: $5/1M (OpenAI) * 1.055
+        output: 0.000031_65, // $31.65/1M - worst-case: $30.00/1M (OpenAI) * 1.055
+        web_search: 0.01, // $10 per 1000 searches (1:1 USD; 10/1K)
+      },
+      {
+        threshold: 272000,
+        input: 0.000010_55, // $10.55/1M - worst-case: $10.00/1M (OpenAI) * 1.055
+        output: 0.000047_475, // $47.475/1M - worst-case: $45.00/1M (OpenAI) * 1.055
+      },
+    ],
+    contextLength: 1_050_000,
+    maxCompletionTokens: 128_000,
+    supportedParameters: [
+      "tools",
+      "tool_choice",
+      "seed",
+      "max_completion_tokens",
+      "response_format",
+      "stop",
+      "temperature",
+      "top_p",
+      "logprobs",
+      "presence_penalty",
+      "frequency_penalty",
+      "logit_bias",
+      "max_tokens",
+      "top_logprobs",
+      "verbosity",
+    ],
+    unsupportedParameters: [],
+    ptbEnabled: false,
+    endpointConfigs: {
+      "*": {},
+    },
+  },
+} satisfies Partial<
+  Record<`${GPT55ModelName}:${ModelProviderName}`, ModelProviderConfig>
+>;
diff --git a/packages/cost/models/authors/openai/gpt-5.5/models.ts b/packages/cost/models/authors/openai/gpt-5.5/models.ts
new file mode 100644
index 0000000000..2474c92717
--- /dev/null
+++ b/packages/cost/models/authors/openai/gpt-5.5/models.ts
@@ -0,0 +1,18 @@
+
+import type { ModelConfig } from "../../../types";
+
+export const models = {
+  "gpt-5.5": {
+    name: "OpenAI GPT-5.5",
+    author: "openai",
+    description:
+      "GPT-5.5 is our newest frontier model for the most complex professional work. Learn more in our latest model guide. Reasoning.effort supports: none, low, medium (default), high and xhigh.",
+    contextLength: 1_050_000,
+    maxOutputTokens: 128_000,
+    created: "2026-04-23T00:00:00.000Z",
+    modality: { inputs: ["text", "image"], outputs: ["text"] },
+    tokenizer: "GPT",
+  },
+} satisfies Record<string, ModelConfig>;
+
+export type GPT55ModelName = keyof typeof models;