Pricing comparison
GPT-4o vs Gemini 3.1 Pro (preview)
Per-token pricing, full-workload cost ladders, and monthly volume projections. Numbers sourced directly from each provider's rate card.
OpenAI
GPT-4o
- Input
- $2.50 / 1M
- Output
- $10.00 / 1M
- Cached input
- $1.250 / 1M
- Context
- 128K
- Max output
- 16K
Gemini 3.1 Pro (preview)
- Input
- $2.00 / 1M
- Output
- $12.00 / 1M
- Cached input
- $0.200 / 1M
- Context
- 1M
- Max output
- -
Cost per request
Four common workload shapes, input tokens and a 1:2 output ratio (a standard chat/completion pattern). Long-context surcharges apply automatically where the provider charges them.
| Scenario | Tokens (in / out) | GPT-4o | Gemini 3.1 Pro (preview) | Winner |
|---|---|---|---|---|
| Short prompt | 100 / 200 | $0.0023 | $0.0026 | GPT-4o |
| Typical request | 1,000 / 2,000 | $0.0225 | $0.0260 | GPT-4o |
| Long document | 10,000 / 5,000 | $0.0750 | $0.0800 | GPT-4o |
| Large prompt | 100,000 / 10,000 | $0.3500 | $0.3200 | Gemini 3.1 Pro (preview) |
Monthly bill at scale
Projected monthly cost at typical request volume, assuming the "typical request" shape above (1k in, 2k out).
| Traffic | Req / month | GPT-4o | Gemini 3.1 Pro (preview) | Delta |
|---|---|---|---|---|
| Small SaaS | 1,000 | $22.50 | $26.00 | GPT-4o -$3.50 |
| Growing product | 10,000 | $225.00 | $260.00 | GPT-4o -$35.00 |
| Heavy usage | 100,000 | $2,250 | $2,600 | GPT-4o -$350.00 |
Which should you use?
For the typical chat-shape request (~1k input, 2k output), GPT-4o comes out 16% cheaper. If you're picking one as the default, that's usually the right choice on cost alone.
Split decision: Gemini 3.1 Pro (preview) has the cheaper input rate, while GPT-4o has the cheaper output rate. RAG and long-context workloads favour the former; generation-heavy workloads (long responses, agentic loops) favour the latter.
Context window differs: Gemini 3.1 Pro (preview) holds 1M of input vs 128K on the other side. If you regularly push past the smaller ceiling, the comparison ends there.
Heads-up: Gemini 3.1 Pro (preview) applies a long-context surcharge above 200K input tokens ($4.00 input / $18.00 output per 1M). Workloads that push past that threshold pay roughly 2x the numbers above.
Live cost calculator
Type in any token counts - both prices update instantly. Uses base input/output rates (no cache discount, no long-context tier).
GPT-4o
$0.0075
per request
Gemini 3.1 Pro (preview)
$0.0080
per request
Try both in the estimator →
Drop your actual prompt in, tokens are counted with the provider's own tokenizer, and the dollar number matches what lands on your invoice.
Frequently asked
- Which is cheaper, GPT-4o or Gemini 3.1 Pro (preview)?
- On a typical 1,000-input / 2,000-output request, GPT-4o costs ~$0.0225 vs ~$0.0260 on Gemini 3.1 Pro (preview). Input or output rates can flip the answer for very lopsided workloads - see the cost ladder above.
- What's the difference in per-token pricing?
- GPT-4o charges $2.50 per 1M input tokens and $10.00 per 1M output tokens. Gemini 3.1 Pro (preview) charges $2.00 / $12.00 per 1M.
- Which has the bigger context window?
- Gemini 3.1 Pro (preview) is larger (1M) vs 128K on the other.
- Is there a cached-input discount on either?
- GPT-4o caches at $1.250 per 1M (50% off). Gemini 3.1 Pro (preview) caches at $0.200 per 1M (90% off). Workloads with repeated static prefixes see the biggest savings.
- Does Gemini 3.1 Pro (preview) have a long-context surcharge?
- Yes. Above 200K input tokens, Gemini 3.1 Pro (preview) bills at $4.00 input / $18.00 output per 1M instead of the standard rate.
- How fresh is this comparison?
- GPT-4o was re-verified on 2026-04-06 and Gemini 3.1 Pro (preview) on 2026-04-06 against each provider's published rate card. Calcis re-checks every row on a rolling schedule and re-deploys when a provider changes pricing.
GPT-4o verified 2026-04-06 · Gemini 3.1 Pro (preview) verified 2026-04-06. Rate cards at OpenAI and Google.