Gemini 3.5 Flash Lite vs GPT-6 Luna

Same documents, same prompt: where each model is right, what it really costs and how fast it answers.

At a glance

Task · documents	English (US)	Czech	German	Spanish	French
Invoice extraction	99.2% / 99.7%	99.5% / 99.3%	100.0% / 99.2%	98.2% / 99.1%	98.7% / 98.9%
Email triage	96.3% / 97.5%	95.8% / 97.9%	94.7% / 97.0%	—	—
Personal data detection	99.5% / 99.6%	98.1% / 99.6%	99.6% / 99.6%	—	—
Contract clauses	100.0% / 99.8%	99.9% / 100.0%	98.0% / 100.0%	—	—

Correct fields: Gemini 3.5 Flash Lite / GPT-6 Luna; the better one in bold. Click a cell to see the details.

Invoice extraction · English (US) (150 documents)

GPT-6 Luna is more accurate by 0.5 pp. GPT-6 Luna is 1.7× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	99.2%	99.7%
Error-free documents	92%	97%
Per 1,000 documents	$0.87	$0.51
To fix / 1,000	80	33
Speed (median)	1.7 sec	3.4 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Supplier	100.0%	100.0%
Supplier ID (EIN, IČO…)	100.0%	100.0%
Invoice number	100.0%	99.3%
Payment reference	96.7%	98.0%
Invoice date	97.3%	100.0%
Due date	99.3%	100.0%
Net by tax rate	98.0%	100.0%
Tax by rate	100.0%	100.0%
Total	100.0%	100.0%
Currency	100.0%	100.0%
Bank account	100.0%	99.3%

Documents where they differ

Atlanta Office Products LLC · A-001328 · PDF text · Gemini 3.5 Flash Lite 9/11, GPT-6 Luna 11/11
Raleigh Engineering Inc. · INV253511 · Scan · Gemini 3.5 Flash Lite 11/11, GPT-6 Luna 10/11

Invoice extraction · Czech (150 documents)

Gemini 3.5 Flash Lite is more accurate by 0.2 pp. GPT-6 Luna is 2× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	99.5%	99.3%
Error-free documents	93%	93%
Per 1,000 documents	$1.03	$0.51
To fix / 1,000	67	67
Speed (median)	1.8 sec	3.2 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Supplier	100.0%	95.3%
Supplier ID (EIN, IČO…)	100.0%	98.7%
VAT ID	100.0%	98.0%
Invoice number	100.0%	100.0%
Payment reference	95.3%	100.0%
Invoice date	100.0%	100.0%
Tax point	100.0%	100.0%
Due date	100.0%	99.3%
Net by tax rate	100.0%	100.0%
Tax by rate	100.0%	100.0%
Total	100.0%	100.0%
Currency	98.7%	100.0%
Bank account	99.3%	99.3%

Documents where they differ

Tesař s.r.o. · 20250237 · Scan · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 10/13
Sedláček s.r.o. · 2025/0774 · Scan · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Pavlík a Zeman s.r.o. · 25500457 · Clean image · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Sedlák s.r.o. · 20250158 · Photo · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Holub s.r.o. · FV2500655 · Scan · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13
Slavěna Pospíšilová · 26200409 · Scan · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13
Agrotrade s.r.o. · DB-2025-00296 · Clean image · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13
Stavebniny Sýkora s.r.o. · FV-2025-00537 · Scan · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13

Invoice extraction · German (150 documents)

Gemini 3.5 Flash Lite is more accurate by 0.8 pp. GPT-6 Luna is 1.9× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	100.0%	99.2%
Error-free documents	100%	91%
Per 1,000 documents	$1.03	$0.54
To fix / 1,000	0	87
Speed (median)	1.5 sec	3.7 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Supplier	100.0%	100.0%
Supplier ID (EIN, IČO…)	100.0%	98.7%
VAT ID	100.0%	99.3%
Invoice number	100.0%	99.3%
Payment reference	100.0%	100.0%
Invoice date	100.0%	98.7%
Tax point	100.0%	100.0%
Due date	100.0%	100.0%
Net by tax rate	100.0%	100.0%
Tax by rate	100.0%	100.0%
Total	100.0%	100.0%
Currency	100.0%	100.0%
Bank account	100.0%	94.0%

Documents where they differ

Malerbetrieb Otfried Haas · RE-2025-00168 · Scan · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13
Braun IT-Service GmbH · RE2500825 · Photo · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13
Wesermetall GmbH · RE2501375 · Scan · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13

Invoice extraction · Spanish (100 documents)

GPT-6 Luna is more accurate by 0.9 pp. GPT-6 Luna is 1.9× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	98.2%	99.1%
Error-free documents	79%	88%
Per 1,000 documents	$1.05	$0.55
To fix / 1,000	210	120
Speed (median)	1.6 sec	3.9 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Supplier	98.0%	99.0%
Supplier ID (EIN, IČO…)	100.0%	100.0%
VAT ID	83.0%	100.0%
Invoice number	100.0%	100.0%
Payment reference	99.0%	98.0%
Invoice date	99.0%	100.0%
Tax point	98.0%	100.0%
Due date	100.0%	100.0%
Net by tax rate	100.0%	100.0%
Tax by rate	100.0%	100.0%
Total	100.0%	100.0%
Currency	100.0%	100.0%
Bank account	100.0%	91.0%

Documents where they differ

Talleres Rozas Zapata S.L. · FV25-01486 · Clean image · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Polo Soluciones Digitales S.A. · 2025/1068 · Scan · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Centro de Formación del Sur S.L.U. · F2025-1424 · Scan · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13
Academia Checa S.L. · F2025-0208 · Clean image · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13
Arranz e Hijos S.L. · F2026-0940 · Clean image · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Leyre Lladó Vall · F2025-1476 · Photo · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Carpintería Montenegro Juárez, S.L.U. · F2025-1314 · PDF text · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Gráficas Levante S.L.U. · F2025-0221 · Clean image · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13

Invoice extraction · French (100 documents)

GPT-6 Luna is more accurate by 0.2 pp. GPT-6 Luna is 1.9× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	98.7%	98.9%
Error-free documents	85%	86%
Per 1,000 documents	$1.07	$0.57
To fix / 1,000	150	143
Speed (median)	1.5 sec	3.8 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Supplier	98.0%	99.0%
Supplier ID (EIN, IČO…)	100.0%	99.0%
VAT ID	100.0%	98.0%
Invoice number	99.0%	99.0%
Payment reference	91.0%	100.0%
Invoice date	98.0%	100.0%
Tax point	98.0%	100.0%
Due date	100.0%	100.0%
Net by tax rate	100.0%	100.0%
Tax by rate	100.0%	100.0%
Total	100.0%	100.0%
Currency	100.0%	100.0%
Bank account	99.0%	90.8%

Documents where they differ

Clément & Fils SASU · 2025-04-431 · Clean image · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Établissements Michel SA · FAC25100622 · Clean image · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Nettoyage Mercier SASU · AC-10176 · Clean image · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13
Carrosserie Gauthier SASU · F-11079 · Scan · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13
Établissements Bertrand SASU · F2025-0066 · Scan · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Établissements Denis SASU · FAC-2025-00031 · Scan · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 12/13
Constance Martin – Rédactrice (EI) · FAC25080663 · Scan · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
SARL Garcia Informatique · F2025-0111 · Clean image · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13

Email triage · English (US) (150 documents)

GPT-6 Luna is more accurate by 1.2 pp. GPT-6 Luna is 3.1× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	96.3%	97.5%
Error-free documents	69%	77%
Per 1,000 documents	$0.42	$0.13
To fix / 1,000	313	227
Speed (median)	0.7 sec	2.5 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Category	100.0%	100.0%
Priority	84.0%	98.0%
Sentiment	82.7%	79.3%
Customer name	100.0%	100.0%
Order number	100.0%	100.0%
Invoice number	100.0%	100.0%
Amount	100.0%	100.0%
Currency	100.0%	100.0%
Deadline	100.0%	100.0%

Documents where they differ

Robert Lewis · Email · Gemini 3.5 Flash Lite 7/9, GPT-6 Luna 9/9
Omar Cabrera · Email · Gemini 3.5 Flash Lite 9/9, GPT-6 Luna 8/9
Luke Sims · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Russell Bates · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Sheila Evans · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Jane Rubio · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Cody Baldwin · Email · Gemini 3.5 Flash Lite 9/9, GPT-6 Luna 8/9
Daniel Stewart · Email · Gemini 3.5 Flash Lite 9/9, GPT-6 Luna 8/9

Email triage · Czech (150 documents)

GPT-6 Luna is more accurate by 2.1 pp. GPT-6 Luna is 2.9× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	95.8%	97.9%
Error-free documents	64%	81%
Per 1,000 documents	$0.51	$0.18
To fix / 1,000	360	187
Speed (median)	0.7 sec	2.6 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Category	100.0%	100.0%
Priority	80.0%	98.7%
Sentiment	84.0%	82.7%
Customer name	98.0%	100.0%
Order number	100.0%	100.0%
Invoice number	100.0%	100.0%
Amount	100.0%	100.0%
Currency	100.0%	100.0%
Deadline	100.0%	100.0%

Documents where they differ

Lucie Kašparová · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Blanka Kučerová · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Andrea Dostálová · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Adam Vaněk · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Magdalena Sedláčková · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Dominika Šťastná · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Růžena Sedláková · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9

Email triage · German (150 documents)

GPT-6 Luna is more accurate by 2.3 pp. GPT-6 Luna is 3.1× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	94.7%	97.0%
Error-free documents	57%	73%
Per 1,000 documents	$0.48	$0.15
To fix / 1,000	433	273
Speed (median)	0.8 sec	2.8 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Category	100.0%	100.0%
Priority	76.0%	99.3%
Sentiment	76.7%	73.3%
Customer name	99.3%	100.0%
Order number	100.0%	100.0%
Invoice number	100.0%	100.0%
Amount	100.0%	100.0%
Currency	100.0%	100.0%
Deadline	100.0%	100.0%

Documents where they differ

Friedbert Hoffmann · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Swantje Noack · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Raymund Weiß · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Irmela Warmer · Email · Gemini 3.5 Flash Lite 9/9, GPT-6 Luna 8/9
Cristina Krause · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Cynthia Hahn · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9
Linda Bähr · Email · Gemini 3.5 Flash Lite 9/9, GPT-6 Luna 8/9
Sibille Lehmann · Email · Gemini 3.5 Flash Lite 8/9, GPT-6 Luna 9/9

Personal data detection · English (US) (150 documents)

GPT-6 Luna is more accurate by 0.1 pp. GPT-6 Luna is 3.9× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	99.5%	99.6%
Error-free documents	97%	97%
Per 1,000 documents	$0.41	$0.11
To fix / 1,000	27	27
Speed (median)	0.8 sec	1.8 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Names	100.0%	98.7%
Email addresses	99.3%	100.0%
Phone numbers	100.0%	100.0%
Addresses	98.7%	98.7%
Dates of birth	98.7%	100.0%
National IDs	100.0%	100.0%
Bank accounts	100.0%	100.0%

Documents where they differ

Matthew Ramirez · Text · Gemini 3.5 Flash Lite 6/7, GPT-6 Luna 7/7
Justin Martinez · Text · Gemini 3.5 Flash Lite 7/7, GPT-6 Luna 6/7
Margaret Mills · Text · Gemini 3.5 Flash Lite 7/7, GPT-6 Luna 6/7

Personal data detection · Czech (150 documents)

GPT-6 Luna is more accurate by 1.5 pp. GPT-6 Luna is 3.8× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	98.1%	99.6%
Error-free documents	88%	97%
Per 1,000 documents	$0.45	$0.12
To fix / 1,000	120	27
Speed (median)	0.8 sec	1.8 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Names	91.3%	100.0%
Email addresses	100.0%	100.0%
Phone numbers	100.0%	100.0%
Addresses	99.3%	97.3%
Dates of birth	96.0%	100.0%
National IDs	100.0%	100.0%
Bank accounts	100.0%	100.0%

Documents where they differ

Růžena Tichá · Text · Gemini 3.5 Flash Lite 6/7, GPT-6 Luna 7/7
Květa Kučerová · Text · Gemini 3.5 Flash Lite 6/7, GPT-6 Luna 7/7
Jonáš Toman · Text · Gemini 3.5 Flash Lite 7/7, GPT-6 Luna 6/7
Artur Musil · Text · Gemini 3.5 Flash Lite 6/7, GPT-6 Luna 7/7
Rudolf Konečný · Text · Gemini 3.5 Flash Lite 6/7, GPT-6 Luna 7/7
Jindřiška Bartošová · Text · Gemini 3.5 Flash Lite 6/7, GPT-6 Luna 7/7
Zikmund Sedláček · Text · Gemini 3.5 Flash Lite 6/7, GPT-6 Luna 7/7

Personal data detection · German (150 documents)

Both are equally accurate. GPT-6 Luna is 3.9× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	99.6%	99.6%
Error-free documents	97%	97%
Per 1,000 documents	$0.45	$0.12
To fix / 1,000	27	27
Speed (median)	0.8 sec	2.2 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Names	97.3%	100.0%
Email addresses	100.0%	100.0%
Phone numbers	100.0%	100.0%
Addresses	100.0%	97.3%
Dates of birth	100.0%	100.0%
National IDs	100.0%	100.0%
Bank accounts	100.0%	100.0%

Documents where they differ

Rosi Karz · Text · Gemini 3.5 Flash Lite 6/7, GPT-6 Luna 7/7
Gunnar Zorbach · Text · Gemini 3.5 Flash Lite 7/7, GPT-6 Luna 6/7
Fritz Rogner · Text · Gemini 3.5 Flash Lite 6/7, GPT-6 Luna 7/7

Contract clauses · English (US) (150 documents)

Gemini 3.5 Flash Lite is more accurate by 0.2 pp. GPT-6 Luna is 3.4× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	100.0%	99.8%
Error-free documents	99%	99%
Per 1,000 documents	$0.69	$0.20
To fix / 1,000	7	13
Speed (median)	1.0 sec	2.7 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Provider	100.0%	98.7%
Provider ID	100.0%	100.0%
Client	100.0%	98.7%
Client ID	100.0%	100.0%
Contract type	99.3%	100.0%
Price (net)	100.0%	100.0%
Currency	100.0%	100.0%
Billing period	100.0%	100.0%
Effective date	100.0%	100.0%
End date	100.0%	100.0%
Notice period (months)	100.0%	100.0%
Late-payment penalty (% per day)	100.0%	100.0%
Governing law	100.0%	100.0%

Documents where they differ

Pittsburgh Construction Co. · Evans Electric LLC · Contract text · Gemini 3.5 Flash Lite 13/13, GPT-6 Luna 11/13

Contract clauses · Czech (150 documents)

GPT-6 Luna is more accurate by 0.1 pp. GPT-6 Luna is 3.2× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	99.9%	100.0%
Error-free documents	98%	100%
Per 1,000 documents	$0.85	$0.27
To fix / 1,000	20	0
Speed (median)	0.9 sec	2.6 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Provider	99.3%	100.0%
Provider ID	100.0%	100.0%
Client	99.3%	100.0%
Client ID	100.0%	100.0%
Contract type	99.3%	100.0%
Price (net)	100.0%	100.0%
Currency	100.0%	100.0%
Billing period	100.0%	100.0%
Effective date	100.0%	100.0%
End date	100.0%	100.0%
Notice period (months)	100.0%	100.0%
Late-payment penalty (% per day)	100.0%	100.0%
Governing law	100.0%	100.0%

Documents where they differ

Elektro Vaněk spol. s r.o. · Fišer a.s. · Contract text · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Autoservis Tesař spol. s r.o. · Tiskárna Beránek s.r.o. · Contract text · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13

Contract clauses · German (150 documents)

GPT-6 Luna is more accurate by 2 pp. GPT-6 Luna is 3× cheaper.

Metric	Gemini 3.5 Flash Lite	GPT-6 Luna
Correct fields	98.0%	100.0%
Error-free documents	84%	100%
Per 1,000 documents	$0.79	$0.27
To fix / 1,000	160	0
Speed (median)	1.0 sec	3.0 sec
Valid answers	100.0%	100.0%

Accuracy per field

Field	Gemini 3.5 Flash Lite	GPT-6 Luna
Provider	100.0%	100.0%
Provider ID	86.0%	100.0%
Client	100.0%	100.0%
Client ID	88.7%	100.0%
Contract type	100.0%	100.0%
Price (net)	100.0%	100.0%
Currency	100.0%	100.0%
Billing period	100.0%	100.0%
Effective date	100.0%	100.0%
End date	99.3%	100.0%
Notice period (months)	100.0%	100.0%
Late-payment penalty (% per day)	100.0%	100.0%
Governing law	100.0%	100.0%

Documents where they differ

Wesermetall e.K. · Weserform GmbH · Contract text · Gemini 3.5 Flash Lite 11/13, GPT-6 Luna 13/13
Hansawerk GmbH · Schreinerei Weber AG · Contract text · Gemini 3.5 Flash Lite 11/13, GPT-6 Luna 13/13
Schulz Systemtechnik GmbH · Elbdata GmbH · Contract text · Gemini 3.5 Flash Lite 11/13, GPT-6 Luna 13/13
Winkler GmbH & Co. KG · Berger & Fuchs e.K. · Contract text · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Maintrans GmbH · Nordbau AG · Contract text · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13
Möller GmbH & Co. KG · Schreinerei Kaiser GmbH · Contract text · Gemini 3.5 Flash Lite 12/13, GPT-6 Luna 13/13