Mistral Large 3 2512 vs Mistral Medium 3.5 vs Mistral Small 4 vs Ministral 3 8B 2512 on invoice text to json
Mistral AI models side by side on "Invoice text to JSON": Ministral 3 8B 2512 scores 10/10; Ministral 3 8B 2512 is the cheapest answer scoring 8+ at $0.04 per 1,000 runs. Outputs, checks, judge reasons, latency and cost.
The prompt every model received
System
You are a data extraction engine. Reply with JSON only, no prose, no code fences.
User
Extract the fields below from the invoice text and return one JSON object with exactly these keys: vendor (string), invoice_number (string), total (number), currency (ISO 4217 string), due_date (YYYY-MM-DD string).
Invoice text:
Northwind Print Co.
Invoice INV-2041
Issued: 15 September 2026
Payment due: 15 October 2026
Items: 500 x A5 flyers @ 1.20 = 600.00; 4 x roll-up banners @ 171.13 = 684.50
Total due: USD 1,284.50
Thank you for your business.
Rubric for the judge: Valid JSON with the five keys, numeric total 1284.5, ISO due date, no extra keys or commentary.
Side by side
Every cell is one OpenRouter call at temperature 0 with the prompt's token cap and reasoning effort "low" where the model supports it. Cost is usage × the catalogue rate in models.json. Quality is one judge call to anthropic/claude-haiku-4.5 against the prompt's rubric, cached per prompt version.
Judge: All five required keys present with correct values: vendor, invoice_number, total (1284.50), currency (USD), and due_date (2026-10-15 in YYYY-MM-DD format); valid JSON with no extra keys or commentary.
Mistral Medium 3.5
mistralai/mistral-medium-3-5
10/10
Latency
451ms
Cost
$0.00276
Per 1,000
$2.76
199 in · 328 out (208 reasoning) · 12 words · checks 6/6
Judge: Output is valid JSON with exactly the five required keys, correct numeric total (1284.5), proper ISO 4217 currency code (USD), correctly formatted due date (2026-10-15), no extra keys or commentary.
Mistral Small 4
mistralai/mistral-small-2603
10/10
Latency
522ms
Cost
$0.00019
Per 1,000
$0.19
199 in · 268 out (187 reasoning) · 12 words · checks 6/6
Judge: Output is valid JSON with exactly the five required keys, correct numeric total (1284.5), proper ISO 4217 currency code (USD), correctly formatted due date (2026-10-15), no extra keys or commentary.
Judge: All five required keys present with correct values: vendor, invoice_number, total as number 1284.5, currency as ISO 4217 code USD, and due_date in YYYY-MM-DD format; no extra keys or commentary.
Frequently asked
▸What does this prompt test?
Extract JSON: Valid JSON with the five keys, numeric total 1284.5, ISO due date, no extra keys or commentary. The deterministic checks are json_valid, json_keys, contains, contains, contains, contains.
▸Which model should I pick for this task?
If the judge's bar of 8/10 is good enough for you, Ministral 3 8B 2512 at $0.04 per 1,000 runs. If you need the top score, Ministral 3 8B 2512 at $0.04 per 1,000 runs.
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