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Gemini 2.5 Flash-Lite vs Gemini 3.1 Pro

Complete pricing and performance comparison between Google's Gemini 2.5 Flash-Lite and Google's Gemini 3.1 Pro.

Quick Verdict

Cheaper
Gemini 2.5 Flash-Lite
20.0x cheaper input, 30.0x cheaper output
Larger Context
Gemini 2.5 Flash-Lite
1.0M vs 1.0M
Higher Quality
Gemini 3.1 Pro
Score: 57 vs 13
Faster
Gemini 2.5 Flash-Lite
336 vs 114 tok/s

Pricing Comparison

SpecGemini 2.5 Flash-LiteGemini 3.1 ProDifference
ProviderGoogleGoogle
Input / 1M tokens$0.1$2Gemini 2.5 Flash-Lite is 95% more expensive
Output / 1M tokens$0.4$12Gemini 2.5 Flash-Lite is 97% more expensive
Context Window1.0M1.0MSame
Max Output66K66K

Performance Benchmarks

MetricGemini 2.5 Flash-LiteGemini 3.1 ProWinner
Quality Index1357Gemini 3.1 Pro
Output Speed336 tok/s114 tok/sGemini 2.5 Flash-Lite
Time to First Token0.27s34.56sGemini 2.5 Flash-Lite
Value (Quality/$)127.028.6Higher = better value

Benchmark data from Artificial Analysis. Quality Index is a composite score across reasoning, coding, and knowledge tasks.

Cost at Scale

Estimated cost at different usage levels (3:1 input-to-output token ratio, typical for chat).

UsageGemini 2.5 Flash-LiteGemini 3.1 ProSavings
Single request
1K in / 300 out
$0.0002$0.0056Gemini 2.5 Flash-Lite saves $0.0054
10 requests
10K in / 3K out
$0.0022$0.056Gemini 2.5 Flash-Lite saves $0.054
100 requests
100K in / 30K out
$0.022$0.560Gemini 2.5 Flash-Lite saves $0.538
1,000 requests
1M in / 300K out
$0.220$5.60Gemini 2.5 Flash-Lite saves $5.38
10,000 requests
10M in / 3M out
$2.20$56.00Gemini 2.5 Flash-Lite saves $53.80
1M requests/mo
1B in / 300M out
$220.00$5600.00Gemini 2.5 Flash-Lite saves $5380.00

Pros & Cons

Gemini 2.5 Flash-Lite Strengths

  • +Cheaper input tokens
  • +Cheaper output tokens
  • +Faster output (336 vs 114 tok/s)
  • +Lower latency (faster first token)

Gemini 3.1 Pro Strengths

  • +Higher quality score (57 vs 13)

When to Use Each Model

Choose Gemini 2.5 Flash-Lite for

  • →Budget-conscious projects where cost is the primary factor
  • →Real-time applications, chat, or autocomplete

Choose Gemini 3.1 Pro for

  • →Tasks requiring maximum accuracy and reasoning

Frequently Asked Questions

Which is cheaper, Gemini 2.5 Flash-Lite or Gemini 3.1 Pro?
For input tokens, Gemini 2.5 Flash-Lite is 20.0x cheaper at $0.1/1M tokens. For output tokens, Gemini 2.5 Flash-Lite is 30.0x cheaper at $0.4/1M tokens. At typical usage (1M input + 300K output), Gemini 2.5 Flash-Lite costs $0.220 vs Gemini 3.1 Pro at $5.60.
What's the context window difference?
Gemini 2.5 Flash-Lite supports 1.0M context (1,048,576 tokens), while Gemini 3.1 Pro supports 1.0M (1,048,576 tokens). Gemini 3.1 Pro can handle 1x more context in a single request.
Which model has better benchmarks?
Quality Index: Gemini 2.5 Flash-Lite scores 13 vs Gemini 3.1 Pro at 57. Speed: Gemini 2.5 Flash-Lite generates 336 tok/s vs Gemini 3.1 Pro at 114 tok/s. Time to first token: Gemini 2.5 Flash-Lite at 0.27s vs Gemini 3.1 Pro at 34.56s.
When should I choose Gemini 2.5 Flash-Lite over Gemini 3.1 Pro?
Choose Gemini 2.5 Flash-Lite when you need: Cheaper input tokens, Cheaper output tokens, Faster output (336 vs 114 tok/s), Lower latency (faster first token). Choose Gemini 3.1 Pro when you need: Higher quality score (57 vs 13).
How much would 10,000 API requests cost?
At 1K input + 300 output tokens per request (typical chat): Gemini 2.5 Flash-Lite = $2.20, Gemini 3.1 Pro = $56.00. At 10K input + 1K output per request (longer conversations): Gemini 2.5 Flash-Lite = $14.00, Gemini 3.1 Pro = $320.00.

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Gemini 2.5 Flash-Lite DetailsGemini 3.1 Pro DetailsFull Pricing TableCost Calculator