Which is more cost-effective, GPT-4o Mini or Gemini 1.5 Flash?

Based on 1M input + 1M output tokens, GPT-4o Mini costs $0.75/month versus Gemini 1.5 Flash at $0.38/month. The cheaper option depends on your token volume and prompt-to-completion ratio. Use the interactive calculator on this page to enter your exact usage.

How accurate is this cost comparison?

List prices come from each provider's own pricing page and every model page shows when they were last verified. The capability scores are iOPTERA's editorial composites — informed by public benchmarks, not benchmark results themselves; the methodology page explains how they are set.

Which model scores higher on benchmarks?

GPT-4o Mini scores 74 in coding and 78 in reasoning benchmarks. Gemini 1.5 Flash scores 72 in coding and 76 in reasoning. See the full 5-category breakdown in the Benchmark Comparison section above.

What are the context window sizes of GPT-4o Mini and Gemini 1.5 Flash?

GPT-4o Mini supports a 128K-token context window while Gemini 1.5 Flash supports 1.0M tokens. A larger context window lets you process more text in a single API call.

Which model is faster for real-time applications?

GPT-4o Mini has a speed score of 97/100 and Gemini 1.5 Flash scores 99/100 on our latency benchmark. For interactive chatbots and low-latency tasks, the higher speed score is preferable.

Can I calculate costs for my specific token volume?

Yes. Use the interactive cost calculator on this page. Enter your monthly token volume and adjust the prompt-to-completion ratio. You can also use presets for common scenarios like Customer Support Bots (~30M tokens/month) or Document Summarizers (~15M tokens/month).

Cost and performance comparison

GPT-4o Mini vs Gemini 1.5 Flash

Model AOpenAI

GPT-4o Mini

Capability score (editorial)78/100

Cost / 1M Tokens: $0.29; 70% in · 30% out mix
Value Index (score÷cost): 273.7; Higher = better value

Speed: 97/100
Context: 128K
Tier: Fast Tier

List price from the OpenAI pricing page, verified September 30, 2026.

Check the source

How we verify prices

Model BGoogle

Gemini 1.5 Flash

Capability score (editorial)76/100

Cost / 1M Tokens: $0.14; 70% in · 30% out mix
Value Index (score÷cost): 555.6; Higher = better value

Speed: 99/100
Context: 1.0M
Tier: Fast Tier

Last list price before the model was retired.

How we verify prices

In-depth analysis

GPT-4o Mini vs Gemini 1.5 Flash: Detailed Comparison

GPT-4o Mini is OpenAI's lightweight-tier language model with a 128K-token context window, excelling at data extraction. Gemini 1.5 Flash from Google is a lightweight-tier model supporting 1.0M tokens in context, with standout performance in data extraction.

GPT-4o Mini costs 2.1x what Gemini 1.5 Flash does for the same text. That is a steep premium, and it buys a 4-point lead on combined coding and reasoning. Whether that trade is worth it depends entirely on how much of your traffic actually needs the harder model — for most workloads the honest answer is a small fraction of it, which is an argument for routing rather than for picking one. GPT-4o Mini is priced at $0.15/M input tokens and $0.60/M output tokens. Gemini 1.5 Flash costs $0.08/M input and $0.30/M output.

On iOPTERA's editorial scores, GPT-4o Mini leads with 74/100 for coding and 78/100 for reasoning, against Gemini 1.5 Flash's 72/100 and 76/100.

Capability breakdown

Across the five core benchmark categories, here is how GPT-4o Mini and Gemini 1.5 Flash stack up head to head:

coding

GPT-4o Mini leads

reasoning

GPT-4o Mini leads

data extraction

GPT-4o Mini leads

creative tasks

GPT-4o Mini leads

vision/multimodal

Gemini 1.5 leads

Best model by task

coding: GPT-4o Mini wins with 74/100
reasoning: GPT-4o Mini wins with 78/100
data extraction: GPT-4o Mini wins with 95/100
creative tasks: GPT-4o Mini wins with 83/100
vision/multimodal: Gemini 1.5 Flash wins with 85/100

Estimated monthly cost at scale

For 10M + 2M tokens of text a month (counted the way OpenAI's tokenizer counts), GPT-4o Mini runs about $2.70 while Gemini 1.5 Flash runs about $1.30 — Gemini 1.5 Flash saves roughly $1.40 (52%) every month.

What actually decides it

GPT-4o Mini and Gemini 1.5 Flash come from different labs, which means different tokenizers, different API shapes, and a second vendor relationship. The same English text does not produce the same token count on both, so a price-per-million comparison understates the difference — measure your own prompts on each before treating the headline rates as the full story.

GPT-4o Mini and Gemini 1.5 Flash were released within 2 months of each other, so they are competing on the same evaluations under roughly the same conditions. That makes a direct benchmark comparison meaningful here in a way it usually is not — neither model has the advantage of being measured on a newer, easier set of tests.

The context gap is the largest single difference on this pair: Gemini 1.5 Flash takes 1.0M tokens against 128K for GPT-4o Mini, roughly 7.8x. That is the difference between feeding in a whole repository or a full contract set and having to chunk it. If your work involves documents you cannot split cleanly, this decides it on its own.

Throughput is close enough to ignore — 99/100 versus 97/100. Neither model will feel noticeably quicker in an interactive product, so latency is not a reason to choose between them.

One practical asymmetry: GPT-4o Mini offers a batch API at 50% off standard rates, and Gemini 1.5 Flash does not. For anything that does not need an answer immediately — nightly enrichment, backfills, evaluation runs — that discount can be worth more than the difference in list price, and it is easy to overlook when comparing headline rates.

GPT-4o Mini is 2.1x the price of Gemini 1.5 Flash. Reserve it for the requests that actually need it and route the rest to Gemini 1.5 Flash — that hybrid beats either model used alone on cost per useful answer.

What you actually pay

The list price is only the start. Prompt caching, batch processing and long prompts change the bill, and each provider sets them differently. Prices per 1M tokens.

Pricing terms beyond the list price, per 1M tokens
Pricing term	GPT-4o Mini	Gemini 1.5 Flash
List price (input / output)	$0.15 / $0.60	$0.075 / $0.30
Cached input	$0.07550% of the input price	—
Batch API	50% off input and output	—
Long prompts	—	—
Input with 80% cache hits	$0.09	—

The last row assumes 80% of input tokens are read from the cache, as in a chat app that re-sends a long system prompt or RAG over the same documents. Cache-write and storage charges are not included.

Gemini also bills cache storage by the hour.

Checked on October 8, 2026 against the pricing pages of OpenAI, Google.

Capability scores

iOPTERA editorial scores across 5 categories — informed by public benchmarks, not measured by us

CategoryGPT-4o MiniGemini 1.5Winner

Coding

Reasoning

Extraction

Creative

Vision

GPT-4o Mini: 4 wins

Gemini 1.5 Flash: 1 wins

GPT-4o Mini leads overall

Speed Score

97/100vs99/100

GPT-4oGemini

Context Window

128Kvs1000K

GPT-4oGemini

What Is a Token?

Models don't read words — they process tokens.

A token is roughly 4 characters of English text (~¾ of a word). Your API bill is priced per million tokens — understanding this directly reduces your costs.

Short phrase

"Hello, world!"

4 tokens

GPT-4o Mini: $0.06
Gemini 1.5 Flash: $0.03

Business email

One typical email (~200 words)

~270 tokens

GPT-4o Mini: $4.05
Gemini 1.5 Flash: $1.94

Code file

50-line Python script

~400 tokens

GPT-4o Mini: $6.00
Gemini 1.5 Flash: $2.88

Prices shown are for 100,000 runs of each workload — one run costs a fraction of a cent on both GPT-4o Mini and Gemini 1.5 Flash, so the number only becomes meaningful at production volume. Input tokens only; add your output volume in the calculator below.

How to check your token usage

response.usage.total_tokens

Every API response includes a usage object. Sum total_tokens across all calls to get your monthly figure, then use the calculator below.

Your Cost Calculator

Enter your actual monthly token usage to see real savings

Quick Presets

Monthly Token Volume

30M tokens

Prompt / Completion Split

Prompt 70%Completion 30%

GPT-4o Mini

$8.55/mo

$102.60/yr

$0.15/M input$0.60/M output

Cheaper

Gemini 1.5 Flash

$4.10/mo

$49.25/yr

$0.075/M input$0.30/M output

Annual Savings

$53.35 saved per year

Gemini 1.5 Flash cheaper · $4.45/mo

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