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Head-to-head comparison

Gemini 3.5 Flash Lite vs GPT-5.3-Codex

Gemini 3.5 Flash Lite (Google) and GPT-5.3-Codex (OpenAI) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 17 August 2026

As of 17 August 2026, GPT-5.3-Codex holds the stronger ModelCap Index position (#20 vs #21); Gemini 3.5 Flash Lite is 5.6× cheaper per output token ($2.50/1M vs $14.00/1M); and Gemini 3.5 Flash Lite offers the longer context window (1M vs 400K tokens).

Which should you choose?

Choose Gemini 3.5 Flash Lite if…

  • API cost matters — $2.50/1M output tokens against $14.00/1M, about 5.6× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.30/1M against $1.75/1M.
  • you need the longer context window — 1M tokens against 400K.
  • you want the more recently listed model — Gemini 3.5 Flash Lite was listed 21 July 2026, GPT-5.3-Codex 24 February 2026.

Choose GPT-5.3-Codex if…

  • you want the stronger overall ModelCap Index position — #20 against #21 (66.4 vs 65.7 points).
  • Artificial Analysis Intelligence Index is your yardstick — 45.5 against 37.4.

Gemini 3.5 Flash Lite vs GPT-5.3-Codex: specs, pricing and context

Specification comparison of Gemini 3.5 Flash Lite and GPT-5.3-Codex
FieldGemini 3.5 Flash LiteGoogleGPT-5.3-CodexOpenAI
ModelCap Index position#21#20
Index score65.766.4
EvidenceMeasuredMeasured
Input price / 1M tokens$0.30$1.75
Output price / 1M tokens$2.50$14.00
Context window1M tokens400K tokens
Max output tokens66K128K
API providers listed22
Weight accessAPI onlyAPI only
Input modalitiesText, Image, Video, File, AudioText, Image, File
First listed21 July 202624 February 2026
PublisherGoogleOpenAI

Evidence: 5 public benchmark observations across 5 boards · 1 public benchmark observation across 1 board. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Gemini 3.5 Flash Lite vs GPT-5.3-Codex

Public benchmark boards where Gemini 3.5 Flash Lite or GPT-5.3-Codex has a published result
BoardGemini 3.5 Flash LiteGPT-5.3-CodexLeads
Arena codingArena (LMArena)15031493–1513—Only one result
LMArena AgentLMArena-10.4%-11.6%–-9.2%—Only one result
ARC-AGI-2ARC Prize Foundation10.3%High—Only one result
Artificial Analysis Intelligence IndexArtificial Analysis37.4intelligence-index45.5intelligence-indexGPT-5.3-Codex

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

Gemini 3.5 Flash Lite vs GPT-5.3-Codex: common questions

Is Gemini 3.5 Flash Lite better than GPT-5.3-Codex?

GPT-5.3-Codex ranks higher on the ModelCap Index as of 17 August 2026: #20 against #21. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it.

Is Gemini 3.5 Flash Lite cheaper than GPT-5.3-Codex?

Gemini 3.5 Flash Lite is cheaper on output tokens: $2.50/1M against $14.00/1M. Input tokens are $0.30/1M for Gemini 3.5 Flash Lite and $1.75/1M for GPT-5.3-Codex. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens.

Which has the bigger context window, Gemini 3.5 Flash Lite or GPT-5.3-Codex?

Gemini 3.5 Flash Lite has the larger context window: 1M tokens against 400K.

Which is better for coding, Gemini 3.5 Flash Lite or GPT-5.3-Codex?

The two models do not share a coding benchmark board on ModelCap yet, so no head-to-head coding score is published; the ModelCap Index position is the closest overall signal.

Are Gemini 3.5 Flash Lite and GPT-5.3-Codex open-weight models?

Gemini 3.5 Flash Lite: API only. GPT-5.3-Codex: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run Gemini 3.5 Flash Lite and GPT-5.3-Codex?

ModelCap currently lists 2 API providers for Gemini 3.5 Flash Lite and 2 for GPT-5.3-Codex, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this Gemini 3.5 Flash Lite vs GPT-5.3-Codex comparison?

Every figure comes from the sealed ModelCap dataset published 17 August 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

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