LLM·Dex
Newsletter

Gemini 2.5 Flash vs GPT-4o

A complete head-to-head: pricing, context window, benchmarks, modality coverage, and openness, with a programmatic verdict synthesized from the underlying data.

Updated

Gemini 2.5 Flash specs · GPT-4o specs
Verdict by category
  • PriceGemini 2.5 Flash

    Gemini 2.5 Flash is roughly 33.3× cheaper on output tokens ($0.30 vs $10.00 per 1M).

  • Context windowGemini 2.5 Flash

    Gemini 2.5 Flash accepts 1.0M tokens vs 128K, 8.2× the room for long documents and codebases.

  • BenchmarksTie

    No directly comparable public benchmarks are available for both models, check the spec sheets for individual scores.

  • ModalitiesTie

    Both handle text, vision, audio.

  • OpennessTie

    Both are closed-weight, API-only.

On balance Gemini 2.5 Flash edges ahead, winning 2 of 5 categories against GPT-4o's 0. Gemini 2.5 Flash is roughly 33.3× cheaper on output tokens ($0.30 vs $10.00 per 1M). Gemini 2.5 Flash accepts 1.0M tokens vs 128K, 8.2× the room for long documents and codebases.

No directly comparable public benchmarks are available for both models, check the spec sheets for individual scores. Both target the same set of modalities (text, vision, audio), so the deciding factors are price, context, and raw quality. Both are closed-weight, API-only.

Gemini 2.5 Flash is the newer of the two, released 11 months after GPT-4o, which usually means a more recent knowledge cutoff and updated safety post-training. Gemini 2.5 Flash is usually picked for rag and long context workloads, while GPT-4o sees more deployments in chatbots and vision. If pricing matters more than every last benchmark point, run the numbers in the calculator below before committing.

Side-by-side specs

SpecGemini 2.5 FlashGPT-4o
ProviderGoogleOpenAI
ReleasedApr 2025May 2024
Modalitiestext, vision, audiotext, vision, audio
Context window1.0M tokens128K tokens
Max output,,
Input · 1M$0.075 / 1M tokens$2.50 / 1M tokens
Output · 1M$0.30 / 1M tokens$10.00 / 1M tokens
Knowledge cutoff2025-012023-10
Open weightsNoNo
API availableYesYes

Pricing at scale

What you'd actually pay at typical workloads. Numbers come from each model's published per-million-token rates.

  • Light usage, 100k in / 50k out per day$0.675 vs $22.50
  • Heavy usage, 1M in / 500k out per day$6.75 vs $225
  • RAG workload, 5M in / 200k out per day$13.05 vs $435

Light usage, 100k in / 50k out per day: $0.675 vs $22.50 per month, model A comes out ahead. Heavy usage, 1M in / 500k out per day: $6.75 vs $225 per month, model A comes out ahead. RAG workload, 5M in / 200k out per day: $13.05 vs $435 per month, model A comes out ahead.

Price calculator

Estimated spend for the listed models at your usage. Numbers are derived from each model's published per-million-token rates.

  • Gemini 2.5 Flash$0.022
  • GPT-4o$0.750

Benchmarks compared

Only sourced numbers. Where a benchmark is missing for one model we show the available value rather than fabricating the other.

Gemini 2.5 FlashGPT-4o
  • MMLU,88.7
  • HumanEval,90.2
Pick Gemini 2.5 Flash if

Gemini 2.5 Flash fits when…

  • Cheap and fast
  • Long context
  • Solid vision
  • Cost-sensitive workloads, 33.3× cheaper than GPT-4o on output tokens.
  • Long-context tasks, handles 1.0M tokens vs 128K for GPT-4o.
Pick GPT-4o if

GPT-4o fits when…

  • Native multimodal
  • Mature SDK and tooling
Don't want either?

Consider Gemini 3 Pro

Google's late-2025 flagship, set new benchmarks on long-context, vision, and reasoning at competitive pricing.

See Gemini 3 Pro specsGemini 2.5 Flash vs Gemini 3 ProGPT-4o vs Gemini 3 Pro

Frequently asked

  • Is Gemini 2.5 Flash or GPT-4o cheaper?
    Gemini 2.5 Flash is cheaper at $0.30 / 1M tokens per million output tokens, vs $10.00 / 1M tokens for GPT-4o.
  • Which has the larger context window?
    Gemini 2.5 Flash accepts 1.0M tokens vs 128K for GPT-4o.
  • Is Gemini 2.5 Flash or GPT-4o better for coding?
    Both Gemini 2.5 Flash and GPT-4o are competitive on coding benchmarks. See each model's individual spec page for HumanEval and SWE-bench scores where published. For an opinionated pick, consult our Best LLM for Coding ranking.
  • Are either of these models open source?
    Neither model ships open weights, both are accessible only via their respective providers' APIs.
  • When were Gemini 2.5 Flash and GPT-4o released?
    Gemini 2.5 Flash was released by Google on 2025-04-09. GPT-4o was released by OpenAI on 2024-05-13.
Friday digest

The week's AI launches, in your inbox.

One short email every Friday, new models, leaks, and quietly-shipped APIs you missed.