ChatGPT vs Grok for coding

Every limit is published. Paid plans also have a monthly fair-use limit on AI cost: Pro $7.50, Max $20, Ultra $42, Studio $85. Using every message on your plan at typical sizes stays under it; very large messages and heavy research use it faster. Every limit, explained.

Coding: GPT-6 Luna passed 5 of 5 and Grok 4.7 5 of 5. GPT-6 Luna answered 6.9× sooner at the median, 4.6 s against 31.6 s. GPT-6 Luna cost 85.8× less, $0.0014 against $0.1229 for the 5 replies. Grok 4.7's replies ran 21% longer, in tokens of reply, thinking not counted.

1. 1. Turn a title into a URL slug

   Everyday. GPT: 4 of 4 models passed, GPT-6 Luna the cheapest at $0.0001 · Grok: 1 of 1 model passed, Grok 4.7 at $0.0078. The prompt in full.

   GPT-6 Luna and Grok 4.7 both passed this one. GPT-6 Luna answered sooner (2.3 s to 14.3 s), and GPT-6 Luna's reply cost less ($0.0001 to $0.0078); GPT-6 Luna wrote 74 tokens of reply, Grok 4.7 73.

   • GPT-6 Luna

     Passed: All 7 tests passed.

     ```javascript
     function slugify(title) {
       return title
         .toLowerCase()
         .normalize("NFD")
         .replace(/[\u0300-\u036f]/g, "")
         .replace(/[^a-z0-9]+/g, "-")
         .replace(/^-|-$/g, "");
     }
     ```

     483 tokens in, 74 out · 2.3 s · $0.0001 · 1 message on Pro · answered by openai/gpt-6-luna via OpenAI · September 27, 2026

   • Grok 4.7

     Passed: All 7 tests passed.

     ```javascript
     function slugify(title) {
       return title
         .normalize("NFD")
         .replace(/\p{M}/gu, "")
         .toLowerCase()
         .replace(/[^a-z0-9]+/g, "-")
         .replace(/^-+|-+$/g, "");
     }
     ```

     1,720 tokens in, 1,012 out (939 of them reasoning) · 14.3 s · $0.0078 · 1 message on Pro · answered by x-ai/grok-4.7 via xAI · October 2, 2026

2. 2. Parse a duration like “1h 30m”

   Everyday. GPT: 4 of 4 models passed, GPT-6 Luna the cheapest at $0.0003 · Grok: 1 of 1 model passed, Grok 4.7 at $0.0167. The prompt in full.

   GPT-6 Luna and Grok 4.7 both passed this one. GPT-6 Luna answered sooner (4.6 s to 31.6 s), and GPT-6 Luna's reply cost less ($0.0003 to $0.0167); GPT-6 Luna wrote 138 tokens of reply, Grok 4.7 171.

   • GPT-6 Luna

     Passed: All 10 tests passed.

     ```javascript
     function parseDuration(text) {
       if (typeof text !== "string") return null;
     
       const match = text.match(/^\s*(?:(\d+)h)?\s*(?:(\d+)m)?\s*(?:(\d+)s)?\s*$/);
       if (!match || !match[1] && !match[2] && !match[3]) return null;
     
       return Number(match[1] || 0) * 3600
         + Number(match[2] || 0) * 60
         + Number(match[3] || 0);
     }
     ```

     468 tokens in, 407 out (269 of them reasoning) · 4.6 s · $0.0003 · 1 message on Pro · answered by openai/gpt-6-luna via OpenAI · September 27, 2026

   • Grok 4.7

     Passed: All 10 tests passed.

     ```javascript
     function parseDuration(text) {
       if (typeof text !== "string") return null;
       const match = text.match(/^\s*(?:(\d+)h)?\s*(?:(\d+)m)?\s*(?:(\d+)s)?\s*$/);
       if (!match || (match[1] == null && match[2] == null && match[3] == null)) return null;
       const hours = match[1] != null ? Number(match[1]) : 0;
       const minutes = match[2] != null ? Number(match[2]) : 0;
       const seconds = match[3] != null ? Number(match[3]) : 0;
       return hours * 3600 + minutes * 60 + seconds;
     }
     ```

     1,706 tokens in, 2,497 out (2,326 of them reasoning) · 31.6 s · $0.0167 · 1 message on Pro · answered by x-ai/grok-4.7 via xAI · October 2, 2026

3. 3. Merge overlapping intervals

   Everyday. GPT: 4 of 4 models passed, GPT-6 Luna the cheapest at $0.0001 · Grok: 1 of 1 model passed, Grok 4.7 at $0.0045. The prompt in full.

   GPT-6 Luna and Grok 4.7 both passed this one. GPT-6 Luna answered sooner (1.5 s to 6.1 s), and GPT-6 Luna's reply cost less ($0.0001 to $0.0045); GPT-6 Luna wrote 130 tokens of reply, Grok 4.7 198.

   • GPT-6 Luna

     Passed: All 7 tests passed.

     ```javascript
     function mergeIntervals(intervals) {
       const sorted = intervals
         .map(([start, end]) => [start, end])
         .sort((a, b) => a[0] - b[0]);
     
       const merged = [];
     
       for (const [start, end] of sorted) {
         const last = merged[merged.length - 1];
     
         if (!last || start > last[1]) {
           merged.push([start, end]);
         } else {
           last[1] = Math.max(last[1], end);
         }
       }
     
       return merged;
     }
     ```

     449 tokens in, 130 out · 1.5 s · $0.0001 · 1 message on Pro · answered by openai/gpt-6-luna via OpenAI · September 27, 2026

   • Grok 4.7

     Passed: All 7 tests passed.

     ```javascript
     function mergeIntervals(intervals) {
       if (!intervals || intervals.length === 0) return [];
     
       const sorted = intervals
         .map((iv) => [iv[0], iv[1]])
         .sort((a, b) => a[0] - b[0] || a[1] - b[1]);
     
       const merged = [[sorted[0][0], sorted[0][1]]];
     
       for (let i = 1; i < sorted.length; i++) {
         const last = merged[merged.length - 1];
         const curr = sorted[i];
         if (curr[0] <= last[1]) {
           if (curr[1] > last[1]) last[1] = curr[1];
         } else {
           merged.push([curr[0], curr[1]]);
         }
       }
     
       return merged;
     }
     ```

     1,684 tokens in, 547 out (349 of them reasoning) · 6.1 s · $0.0045 · 1 message on Pro · answered by x-ai/grok-4.7 via xAI · October 2, 2026

4. 4. Evaluate an arithmetic expression, no eval

   Hard. GPT: 4 of 4 models passed, GPT-6 Luna the cheapest at $0.0006 · Grok: 1 of 1 model passed, Grok 4.7 at $0.0574. The prompt in full.

   GPT-6 Luna and Grok 4.7 both passed this one. GPT-6 Luna answered sooner (8.8 s to 110.1 s), and GPT-6 Luna's reply cost less ($0.0006 to $0.0574); GPT-6 Luna wrote 552 tokens of reply, Grok 4.7 613.

   • GPT-6 Luna

     Passed: All 15 tests passed.

     ```javascript
     function evaluate(expression) {
       if (typeof expression !== "string") {
         throw new Error("Expression must be a string");
       }
     
       let index = 0;
     
       function skipSpaces() {
         while (index < expression.length && /\s/.test(expression[index])) {
           index++;
         }
       }
     
       function parsePrimary() {
         skipSpaces();
     
         if (expression[index] === "(") {
           index++;
           const value = parseExpression();
           skipSpaces();
           if (expression[index] !== ")") throw new Error("Missing closing parenthesis");
           index++;
           return value;
         }
     
         const start = index;
         let digitsBefore = 0;
         while (/\d/.test(expression[index] || "")) {
           index++;
           digitsBefore++;
         }
     
         let digitsAfter = 0;
         if (expression[index] === ".") {
           index++;
           while (/\d/.test(expression[index] || "")) {
             index++;
             digitsAfter++;
           }
         }
     
         if (digitsBefore === 0 && digitsAfter === 0) {
           throw new Error("Expected a number or parenthesized expression");
         }
     
         return Number(expression.slice(start, index));
       }
     
       // Unary minus has lower precedence than exponentiation, but is allowed
       // on an exponent's right-hand side.
       function parseUnary() {
         skipSpaces();
         if (expression[index] === "-") {
           index++;
           return -parseUnary();
         }
         return parsePower();
       }
     
       function parsePower() {
         let value = parsePrimary();
         skipSpaces();
     
         if (expression[index] === "^") {
           index++;
           value **= parseUnary();
         }
     
         return value;
       }
     
       function parseProduct() {
         let value = parseUnary();
     
         while (true) {
           skipSpaces();
           const operator = expression[index];
           if (operator !== "*" && operator !== "/") break;
     
           index++;
           const right = parseUnary();
           value = operator === "*" ? value * right : value / right;
         }
     
         return value;
       }
     
       function parseExpression() {
         let value = parseProduct();
     
         while (true) {
           skipSpaces();
           const operator = expression[index];
           if (operator !== "+" && operator !== "-") break;
     
           index++;
           const right = parseProduct();
           value = operator === "+" ? value + right : value - right;
         }
     
         return value;
       }
     
       const result = parseExpression();
       skipSpaces();
       if (index !== expression.length) throw new Error("Unexpected input");
     
       return result;
     }
     ```

     549 tokens in, 1,007 out (455 of them reasoning) · 8.8 s · $0.0006 · 1 message on Pro · answered by openai/gpt-6-luna via OpenAI · September 27, 2026

   • Grok 4.7

     Passed: All 15 tests passed.

     ```javascript
     function evaluate(expression) {
       if (typeof expression !== 'string') {
         throw new Error('Invalid expression');
       }
     
       const s = expression;
       let i = 0;
     
       function skip() {
         while (i < s.length && s[i] === ' ') i++;
       }
     
       function parseExpression() {
         let value = parseTerm();
         while (true) {
           skip();
           if (s[i] === '+') {
             i++;
             value += parseTerm();
           } else if (s[i] === '-') {
             i++;
             value -= parseTerm();
           } else {
             break;
           }
         }
         return value;
       }
     
       function parseTerm() {
         let value = parseUnary();
         while (true) {
           skip();
           if (s[i] === '*') {
             i++;
             value *= parseUnary();
           } else if (s[i] === '/') {
             i++;
             value /= parseUnary();
           } else {
             break;
           }
         }
         return value;
       }
     
       function parseUnary() {
         skip();
         if (s[i] === '-') {
           i++;
           return -parseUnary();
         }
         return parsePower();
       }
     
       function parsePower() {
         const base = parsePrimary();
         skip();
         if (s[i] === '^') {
           i++;
           return base ** parseUnary();
         }
         return base;
       }
     
       function parsePrimary() {
         skip();
         if (s[i] === '(') {
           i++;
           const value = parseExpression();
           skip();
           if (s[i] !== ')') throw new Error('Invalid expression');
           i++;
           return value;
         }
         return parseNumber();
       }
     
       function parseNumber() {
         skip();
         const start = i;
         if (i >= s.length || s[i] < '0' || s[i] > '9') {
           throw new Error('Invalid expression');
         }
         while (i < s.length && s[i] >= '0' && s[i] <= '9') i++;
         if (s[i] === '.') {
           i++;
           if (i >= s.length || s[i] < '0' || s[i] > '9') {
             throw new Error('Invalid expression');
           }
           while (i < s.length && s[i] >= '0' && s[i] <= '9') i++;
         }
         return Number(s.slice(start, i));
       }
     
       const value = parseExpression();
       skip();
       if (i !== s.length) throw new Error('Invalid expression');
       return value;
     }
     ```

     1,786 tokens in, 9,267 out (8,654 of them reasoning) · 110.1 s · $0.0574 · 1 message on Pro · answered by x-ai/grok-4.7 via xAI · October 2, 2026

5. 5. Parse CSV with quoted fields

   Hard. GPT: 4 of 4 models passed, GPT-6 Luna the cheapest at $0.0004 · Grok: 1 of 1 model passed, Grok 4.7 at $0.0364. The prompt in full.

   GPT-6 Luna and Grok 4.7 both passed this one. GPT-6 Luna answered sooner (7.2 s to 72.2 s), and GPT-6 Luna's reply cost less ($0.0004 to $0.0364); GPT-6 Luna wrote 315 tokens of reply, Grok 4.7 402.

   • GPT-6 Luna

     Passed: All 8 tests passed.

     ```javascript
     function parseCsv(text) {
       if (text === "") return [];
     
       const rows = [];
       let row = [];
       let field = "";
       let inQuotes = false;
       let endedWithRowBreak = false;
     
       for (let i = 0; i < text.length; i++) {
         const char = text[i];
     
         if (inQuotes) {
           if (char === '"') {
             if (text[i + 1] === '"') {
               field += '"';
               i++;
             } else {
               inQuotes = false;
             }
           } else {
             field += char;
           }
           endedWithRowBreak = false;
           continue;
         }
     
         if (char === '"' && field === "") {
           inQuotes = true;
           endedWithRowBreak = false;
         } else if (char === ",") {
           row.push(field);
           field = "";
           endedWithRowBreak = false;
         } else if (char === "\n" || (char === "\r" && text[i + 1] === "\n")) {
           row.push(field);
           rows.push(row);
           row = [];
           field = "";
           if (char === "\r") i++;
           endedWithRowBreak = true;
         } else {
           field += char;
           endedWithRowBreak = false;
         }
       }
     
       if (!endedWithRowBreak) {
         row.push(field);
         rows.push(row);
       }
     
       return rows;
     }
     ```

     481 tokens in, 762 out (447 of them reasoning) · 7.2 s · $0.0004 · 1 message on Pro · answered by openai/gpt-6-luna via OpenAI · September 27, 2026

   • Grok 4.7

     Passed: All 8 tests passed.

     ```javascript
     function parseCsv(text) {
       if (text === "") return [];
     
       const rows = [];
       let row = [];
       let field = "";
       let inQuotes = false;
       let atFieldStart = true;
       let endedOnBreak = false;
     
       for (let i = 0; i < text.length; ) {
         const c = text[i];
     
         if (inQuotes) {
           if (c === '"') {
             if (text[i + 1] === '"') {
               field += '"';
               i += 2;
             } else {
               inQuotes = false;
               i += 1;
             }
           } else {
             field += c;
             i += 1;
           }
           endedOnBreak = false;
           continue;
         }
     
         if (atFieldStart && c === '"') {
           inQuotes = true;
           atFieldStart = false;
           endedOnBreak = false;
           i += 1;
           continue;
         }
     
         if (c === ",") {
           row.push(field);
           field = "";
           atFieldStart = true;
           endedOnBreak = false;
           i += 1;
           continue;
         }
     
         if (c === "\n" || (c === "\r" && text[i + 1] === "\n")) {
           row.push(field);
           rows.push(row);
           row = [];
           field = "";
           atFieldStart = true;
           endedOnBreak = true;
           i += c === "\r" ? 2 : 1;
           continue;
         }
     
         field += c;
         atFieldStart = false;
         endedOnBreak = false;
         i += 1;
       }
     
       if (!endedOnBreak) {
         row.push(field);
         rows.push(row);
       }
     
       return rows;
     }
     ```

     1,718 tokens in, 5,854 out (5,452 of them reasoning) · 72.2 s · $0.0364 · 1 message on Pro · answered by x-ai/grok-4.7 via xAI · October 2, 2026

• GPT-6 Astra vs Grok 4.7: 5 of 5 each; GPT-6 Astra answered 3.9× sooner at the median and cost 1.1× less. GPT-6 Astra vs Grok 4.7, on every job.

• GPT-6.1 Sol vs Grok 4.7: 5 of 5 each; GPT-6.1 Sol answered 6.6× sooner at the median and cost 10.7× less.

• GPT-6 Sol vs Grok 4.7: 5 of 5 each; GPT-6 Sol answered 6.6× sooner at the median and cost 4.7× less. GPT-6 Sol vs Grok 4.7, on every job.

• GPT-6 Luna vs Grok 4.7: 5 of 5 each; GPT-6 Luna answered 6.9× sooner at the median and cost 85.8× less. GPT-6 Luna vs Grok 4.7, on every job.

Every GPT and Grok reply above was checked the same way as every other model's, by the rules published with the prompts: how the coding prompts are scored, and each one in full.

• The lineups

  GPT: 4 models, GPT-6 Astra, GPT-6.1 Sol, GPT-6 Sol, and GPT-6 Luna. Grok: one model, Grok 4.7.

• Price per message

  The least expensive GPT model is GPT-6 Luna (60 messages a day on Pro); Grok's one model is Grok 4.7 (250 messages a month on Pro).

• Context window

  GPT goes up to 1.05M tokens (GPT-6 Astra); Grok up to 500K tokens (Grok 4.7).

• Images and PDFs

  Every model here reads images. Every model here takes a PDF as a whole file.

• On the Free plan

  Free's one-time trial of 5 messages covers GPT-6.1 Sol, GPT-6 Sol, GPT-6 Luna, and Grok 4.7. Paid plans have every model, with messages every month.

In llmwise, a message to GPT goes to its maker, OpenAI, or through OpenRouter when llmwise can't reach the maker directly. Grok models are served only through OpenRouter, by endpoints that don't store or train on prompts. The Privacy Policy has the details.