Gemini 3.8 Flash High vs Gemini 4 Carbon High compared

Gemini 4 Carbon High leads the intelligence index 60.0 to 30.8. Gemini 3.8 Flash High costs 81% less on blended price. See token costs, speed and which to pick.

Metric	Gemini 3.8 Flash (High)	Gemini 4 Carbon (High)
Intelligence Index	30.8	60.0
Input price (per 1M tokens)	$0.75	$4.00
Output price (per 1M tokens)	$3.75	$20.00
Output speed (tokens/s)	121	91
Time to first token	27s	2.0 min
Release date	2026-09-02	2026-10-28

Metric

Gemini 3.8 Flash (High)

Gemini 4 Carbon (High)

Intelligence Index

30.8

60.0

Input price (per 1M tokens)

$0.75

$4.00

Output price (per 1M tokens)

$3.75

$20.00

Output speed (tokens/s)

121

Time to first token

27s

2.0 min

Release date

2026-09-02

2026-10-28

Staying with Google still leaves a decision: Gemini 3.8 Flash (High) or Gemini 4 Carbon (High). The headline gap is on the intelligence index, where Gemini 4 Carbon High scores 60.0 and Gemini 3.8 Flash High 30.8. Everything below is read from the benchmark, price and speed data in Franklin AI's catalogue; nothing here comes from a hands-on test.

Reasoning and overall scores

Gemini 3.8 Flash High records 30.8 on the intelligence index and Gemini 4 Carbon High records 60.0. The difference is large enough that the lower-scoring model has to win on cost or speed to stay in the running. In relative terms, Gemini 4 Carbon High scores 95% higher.

Across the 109 active models with an intelligence score in the catalogue, Gemini 3.8 Flash High ranks 50th and Gemini 4 Carbon High ranks 1st.

There are no coding or math index scores for either model in the catalogue, which keeps this comparison at the aggregate level.

Gemini 3.8 Flash High is the faster writer

Once a response is under way, Gemini 3.8 Flash High produces roughly 121 tokens per second against 91 tokens per second for Gemini 4 Carbon High. Gemini 3.8 Flash High is ahead by 33% on throughput. Time to first token is 27 seconds for Gemini 3.8 Flash High and 2.0 minutes for Gemini 4 Carbon High. Gemini 3.8 Flash High gets to its first token 4.4 times as fast. Waits that long are felt on every chat-style request, though they matter less for batch jobs.

Put together, a 1,500-token answer would take about 40 seconds from Gemini 3.8 Flash High and 2.3 minutes from Gemini 4 Carbon High, counting the first-token wait.

Cost: Gemini 3.8 Flash High is cheaper

Per million tokens, Gemini 3.8 Flash High charges $0.75 for input and $3.75 for output, while Gemini 4 Carbon High charges $4.00 and $20.00. Gemini 4 Carbon High costs 5.3 times as much per output token.

Take 1 million input tokens and 200,000 output tokens: that comes to $1.50 on Gemini 3.8 Flash High and $8.00 on Gemini 4 Carbon High. Scale it up to an agent that reads 50 million tokens and writes 5 million in a month and the bill is $56.25 for Gemini 3.8 Flash High against $300 for Gemini 4 Carbon High.

Score per dollar

A blunt value measure, blended price over intelligence score, puts Gemini 3.8 Flash High at $0.049 and Gemini 4 Carbon High at $0.13 per point. So Gemini 4 Carbon High buys its higher score at a premium, while Gemini 3.8 Flash High is the value pick, paying 63% less per point.

Generation gap

The release dates are September 2, 2026 for Gemini 3.8 Flash High and October 28, 2026 for Gemini 4 Carbon High, about 2 months apart.

FAQ

Is Gemini 4 Carbon High better than Gemini 3.8 Flash High?

It depends on what you need: Gemini 4 Carbon High scores higher on the intelligence index, 60.0 to 30.8; Gemini 3.8 Flash High is 81% cheaper on blended price; and Gemini 3.8 Flash High streams output 1.3 times as fast.

Does Gemini 3.8 Flash High respond faster than Gemini 4 Carbon High?

Gemini 3.8 Flash High generates output faster, at 121 tokens per second against 91 tokens per second. Gemini 3.8 Flash High reaches its first token sooner (27 seconds against 2.0 minutes).

Who makes Gemini 3.8 Flash High and Gemini 4 Carbon High?

Both are Google models, listed as separate models in the catalogue. Gemini 3.8 Flash High was released on September 2, 2026 and Gemini 4 Carbon High on October 28, 2026.

Which is newer, Gemini 3.8 Flash High or Gemini 4 Carbon High?

Gemini 4 Carbon High is newer. It was released on October 28, 2026, about 2 months after Gemini 3.8 Flash High (September 2, 2026).

Is Gemini 4 Carbon High cheaper than Gemini 3.8 Flash High?

Gemini 3.8 Flash High is cheaper on a blended basis. Gemini 3.8 Flash High lists $0.75 per million input tokens and $3.75 per million output tokens; Gemini 4 Carbon High lists $4.00 and $20.00. For 1 million input and 200,000 output tokens that is $1.50 against $8.00.

Final whistle

The verdict: on balance the numbers favour Gemini 4 Carbon High, though Gemini 3.8 Flash High keeps a case of its own. Pick Gemini 3.8 Flash High if cost matters ($3.75 against $20.00 per million output tokens) and users are waiting on the first word. Pick Gemini 4 Carbon High if you need the higher overall score (60.0 against 30.8) and you want the more recent release.

Where the numbers come from

The scores, speed and prices in this comparison come from independent third-party model evaluations that Franklin AI syncs each day, and the article was written from a snapshot of them. For the latest results, open the Gemini 3.8 Flash (High) and Gemini 4 Carbon (High) pages. The AI Benchmark methodology explains how that data is collected and shown.