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Head to head · prices checked 22 September 2026

GPT-5.6 Terra vs Gemini 3.8 Flash

OpenAI's and Google's mid tiers, the usual shortlist for high-volume business tasks. Both list prices from the makers’ own pages, and what three everyday jobs cost on each.

What a job costsEvery model

US dollars, standard rate, shortest context band. Price only: this page does not rank quality.

1,000 support replies
2.9×what GPT-5.6 Terra costs next to Gemini 3.8 Flash
GPT-5.6 Terra
$10.80
Gemini 3.8 Flash
$3.75
GPT-5.6 Terra, per M tokens
$2 / $12
Gemini 3.8 Flash, per M tokens
$0.75 / $3.75

3,000 tokens in and 400 out each, at list price.

Per million tokens, GPT-5.6 Terra costs $2 in and $12 out; Gemini 3.8 Flash costs $0.75 in and $3.75 out. 1,000 support replies cost $10.80 on GPT-5.6 Terra and $3.75 on Gemini 3.8 Flash, so GPT-5.6 Terra costs 2.9 times as much. Both read up to 1.05M tokens at once.

Side by side

Each maker’s published rate for its standard tier. Cached input is what a repeated prompt prefix costs once the provider has stored it.

GPT-5.6 Terra and Gemini 3.8 Flash: list prices and specifications
FactGPT-5.6 TerraGemini 3.8 Flash
MakerOpenAIGoogle
TierWorkhorsesWorkhorses
Input, per M tokens$2.00$0.75
Output, per M tokens$12.00$3.75
Cached input$0.20$0.075
Context window1.05M1.05M
Released9 Jul 20262 Sep 2026
WeightsClosedClosed

What a job costs on each

1,000 runs of each job at the two list prices. The gap moves from job to job because the models price input, output and cached context differently.

Cost of 1,000 runs of three jobs on GPT-5.6 Terra and Gemini 3.8 Flash
JobGPT-5.6 TerraGemini 3.8 FlashCheaper
Support reply3,000 in, 400 out.$10.80$3.75Gemini 3.8 Flash, 65% less
Document summary25,000 in, 1,000 out.$62.00$22.50Gemini 3.8 Flash, 64% less
Agent task80,000 in (70,000 cached), 3,000 out.$70.00$24.00Gemini 3.8 Flash, 66% less

The token counts are ours, chosen to look like real work; the prices are the makers’. A model with no published cache price bills the agent task’s repeated context at its full input rate.

The small print

What each base rate leaves out, from the makers’ own pages: surcharges, discounts, promotions and cache pricing.

GPT-5.6 Terra
OpenAI calls it the mini tier of the 5.6 family; tiered mid here on price. Price cut 20% on 2026-07-30. Requests above 272K input tokens bill 2x input and 1.5x output ($4 / $18). Cache write $2.50. Batch and Flex 50% off. Data residency adds 10%. OpenAI’s pricing page
Gemini 3.8 Flash
Launch price through 2026-12-31; from 2027-01-01 it becomes $1.50 / $7.50, cached $0.15. Batch and Flex 50% off; Priority $1.35 / $6.75. Cache storage $0.50 per MTok per hour (rising to $1.00). Google’s pricing page

Other comparisons

Every head to head on the list that involves GPT-5.6 Terra or Gemini 3.8 Flash.

Run both for a quarter of list price

AIGROW API credit covers GPT-5.6 Terra and Gemini 3.8 Flash and is metered at the list prices above: $25 buys $100 of usage.

See API creditCompare every model

Prices checked 22 September 2026