Grok 4.3 vs Gemini 3.8 Flash
xAI's low-cost model against Google's mid tier, with cheaper output on the Grok side. Both list prices from the makers’ own pages, and what three everyday jobs cost on each.
US dollars, standard rate, shortest context band. Price only: this page does not rank quality.
- Grok 4.3
- $4.75
- Gemini 3.8 Flash
- $3.75
- Grok 4.3, per M tokens
- $1.25 / $2.50
- 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, Grok 4.3 costs $1.25 in and $2.50 out; Gemini 3.8 Flash costs $0.75 in and $3.75 out. 1,000 support replies cost $4.75 on Grok 4.3 and $3.75 on Gemini 3.8 Flash, so Grok 4.3 costs 27% more. Grok 4.3 reads up to 1M tokens at once, Gemini 3.8 Flash up to 1.05M.
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.
| Fact | Grok 4.3 | Gemini 3.8 Flash |
|---|---|---|
| Maker | xAI | |
| Tier | Small and fast | Workhorses |
| Input, per M tokens | $1.25 | $0.75 |
| Output, per M tokens | $2.50 | $3.75 |
| Cached input | $0.20 | $0.075 |
| Context window | 1M | 1.05M |
| Released | Not published | 2 Sep 2026 |
| Weights | Closed | Closed |
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.
| Job | Grok 4.3 | Gemini 3.8 Flash | Cheaper |
|---|---|---|---|
| Support reply3,000 in, 400 out. | $4.75 | $3.75 | Gemini 3.8 Flash, 21% less |
| Document summary25,000 in, 1,000 out. | $33.75 | $22.50 | Gemini 3.8 Flash, 33% less |
| Agent task80,000 in (70,000 cached), 3,000 out. | $34.00 | $24.00 | Gemini 3.8 Flash, 29% 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.
- Grok 4.3
- Prompts of 200K tokens or more: $2.50 / $5, cached $0.40. Batch 20% off. xAI no longer lists 'fast' variants; this is its low-cost model. Release date not stated on the official pages. xAI’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 Grok 4.3 or Gemini 3.8 Flash.
Run Gemini 3.8 Flash for a quarter of list price
AIGROW API credit covers Gemini 3.8 Flash and is metered at the list prices above: $25 buys $100 of usage.
Prices checked 22 September 2026