GPT-5.6 Terra vs DeepSeek V4-Flash
OpenAI's GPT-5.6 Terra and DeepSeek's DeepSeek V4-Flash both target production language workloads, but they price and behave differently. Here is the side-by-side.
Pricing checked against provider documentation on . How we verify
The short answer
DeepSeek V4-Flash is the cheaper option — roughly 13.6x less on a blended workload, and it suits the cheapest capable open-weight option. GPT-5.6 Terra justifies its premium when you need balanced production workloads.
OpenAI • GPT-5.6
$2.00 / $12.00
/ 1M tokens (input / output)
The everyday tier of the GPT-5.6 family, roughly corresponding to the old 'mini' slot but benchmarking above the previous generation's flagship. For most application backends this is the default worth trying before reaching for Sol, since it clears Claude Fable 5 on several evals at a fraction of the cost.
DeepSeek • DeepSeek V4
$0.22 / $0.66
/ 1M tokens (input / output)
A 284B-parameter MoE with only 13B active, which is why it runs fast and prices low. Notable for a 384K maximum output — far beyond the 128K most frontier models cap at — and for supporting both thinking and non-thinking modes, so you can switch reasoning off on easy requests rather than paying for it.
Input price
DeepSeek V4-Flash is 89% cheaper than GPT-5.6 Terra on input tokens.
Output price
DeepSeek V4-Flash is 95% cheaper than GPT-5.6 Terra on output tokens — usually the side that dominates the bill.
Monthly cost at three workload sizes
Standard (non-batch, non-cached) rates. Reasoning models will exceed these figures because thinking tokens bill as output.
| Workload | GPT-5.6 Terra | DeepSeek V4-Flash | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $4 | $0 | $4 |
| Moderate — 10M in / 2M out | $44 | $4 | $40 |
| Heavy — 100M in / 20M out | $440 | $35 | $405 |
Specification comparison
| Attribute | GPT-5.6 Terra | DeepSeek V4-Flash |
|---|---|---|
| Input (/ 1M tokens) | $2.00 | $0.22 |
| Output (/ 1M tokens) | $12.00 | $0.66 |
| Cached input | $0.20 | $0.01 |
| Context window | 1,048,576 tokens | 1,000,000 tokens |
| Max output | 128,000 tokens | 384,000 tokens |
| Native reasoning | Yes | Yes |
| Knowledge cutoff | 2026-02 | 2026-03 |
| Relative latency | medium | low |
| Open weights | No | MIT |
| API model ID | gpt-5.6-terra | deepseek-v4-flash |
| Status | stable | stable |
GPT-5.6 Terra: Cut 20% from the $2.50/$15 launch price on 2026-07-30.
DeepSeek V4-Flash: Off-peak rate shown. Peak rates double ($0.44 / $1.32) during 01:00–04:00 and 06:00–10:00 UTC on weekdays. Superseded the earlier flat-rate pricing of $0.14 / $0.28 that many comparison sites still quote.
Choose GPT-5.6 Terra if…
- Customer support and chat backends
- RAG and document processing pipelines
- Mid-complexity coding tasks
- Tool-calling agents at scale
Choose DeepSeek V4-Flash if…
- High-volume classification and extraction
- Very long generated outputs
- Budget coding agents
- Local deployment on modest hardware
Frequently asked
Is GPT-5.6 Terra or DeepSeek V4-Flash cheaper?
DeepSeek V4-Flash is cheaper. On a blended 3:1 input-to-output workload it costs about 13.6x less than GPT-5.6 Terra.
Which has the larger context window, GPT-5.6 Terra or DeepSeek V4-Flash?
GPT-5.6 Terra has the larger window at 1.05M tokens versus 1M.
Should I use GPT-5.6 Terra or DeepSeek V4-Flash?
Pick GPT-5.6 Terra for balanced production workloads. Pick DeepSeek V4-Flash for the cheapest capable open-weight option. If cost dominates the decision, DeepSeek V4-Flash wins; if you need the capability ceiling, benchmark both on your own evals before committing.