Quick Verdict
| Need | Better first pick | Why |
|---|---|---|
| Output-heavy work beyond nano | DeepSeek V4 Flash off-peak | Its output and cached-input economics remain competitive, with all-weekend off-peak billing |
| Input-heavy utility calls | GPT-4.1 nano or GPT-5.6 Luna | Smaller OpenAI routes can now beat Flash on uncached input |
| Budget escalation | Test V4 Pro against GPT-5.4 mini and GPT-5.6 Luna | The new DeepSeek schedule removed the automatic price win |
| OpenAI ecosystem | GPT-5.6 Luna or Sol | Better tooling, multimodal coverage, integrations, and procurement familiarity |
| Premium reasoning | GPT-5.6 Sol | Expensive, but the safer OpenAI escalation route |
For live model tables, use DeepSeek pricing, OpenAI pricing, and the calculator above.
How DeepSeek Billing Works Now
DeepSeek replaced one always-on V4 rate with peak and off-peak billing at 16:00 UTC on August 16. Peak windows run from 01:00–04:00 UTC and 06:00–10:00 UTC, Monday through Friday. Weekday hours outside those windows and every hour on Saturday and Sunday use the off-peak tier.
Against the previous always-on rate, Flash’s off-peak input rose 57% and output rose 136%. Pro’s off-peak input rose 52% and output rose 128%. Peak rates are twice the new off-peak rates. The live table and chart above are generated from today’s pricing.json; DeepSeek’s complete tier structure and UTC windows are also available in the pricing API and official pricing documentation.
This does not erase DeepSeek’s advantage against OpenAI’s flagship route. It does mean Flash is no longer the universal price winner against every small OpenAI model, while Pro must now prove a quality or output-cost advantage over GPT-5.4 mini and GPT-5.6 Luna.
Cost Scenarios
| Scenario | Token mix | Cheapest likely route | Why |
|---|---|---|---|
| Support bot | Many short chats | Flash off-peak or GPT-5.6 Luna | Output length, weekday traffic hour, and first-pass resolution decide the winner |
| Document summaries | Heavy input, shorter output | Small OpenAI first | Lower uncached input can outweigh DeepSeek’s output advantage |
| Coding assistant | Large input and output | Test V4 Pro, GPT-5.6 Luna, and GPT-5.4 mini | Quality and retries matter more than the sticker price |
| Cached agent context | Repeated prompts and schemas | DeepSeek off-peak | Cache economics remain attractive, especially for schedulable weekend runs, but only if prefixes actually hit |
The real comparison is cost per accepted answer. If DeepSeek needs more retries, longer prompts, or extra review, the savings shrink. If it passes evals, the savings compound quickly.
What You Give Up With DeepSeek
OpenAI still has the stronger ecosystem: SDK familiarity, third-party integrations, multimodal breadth, enterprise comfort, and premium model depth. DeepSeek is strongest when the task is text-first, quality is measurable, and cost is the constraint.
If you want a managed open-model fallback instead of relying on one direct provider, compare Novita’s current model catalog on the same evaluation set.
Affiliate disclosure: AI Pricing Guru may earn a commission from the sponsored link above at no extra cost to you. It does not affect our recommendations.
Routing Pattern
| Workload | Default route | Escalation route |
|---|---|---|
| Classification or tagging | GPT-4.1 nano or GPT-5.6 Luna | DeepSeek V4 Flash |
| Support drafts | DeepSeek V4 Flash off-peak | GPT-5.6 Luna or V4 Pro |
| RAG answers | DeepSeek V4 Pro | GPT-5.6 Sol |
| Coding triage | DeepSeek V4 Flash off-peak | GPT-5.6 Luna or V4 Pro |
| Hard code changes | Test V4 Pro and GPT-5.6 Luna | GPT-5.6 Sol or a specialist coding model |
FAQ
Is DeepSeek still cheaper than OpenAI?
Against GPT-5.6 Sol, usually yes. Against GPT-4.1 nano, GPT-5.4 mini, or GPT-5.6 Luna, the answer depends on the weekday UTC billing window, input-to-output ratio, cache hits, retries, and task success rate. DeepSeek stays off-peak throughout the weekend.
Is DeepSeek V4 Pro cheaper than GPT-5.4 mini?
Not across every token category after the August 16 change. Compare your input-to-output mix at the hours when traffic runs, then include quality, tooling, governance, and retries.
Should I replace GPT-5.6 Sol with DeepSeek?
Not blindly. Use DeepSeek to cut bulk text costs, then keep GPT-5.6 Sol or another premium model for tasks where quality risk is high.
Which model should startups test first?
Start with DeepSeek V4 Flash, GPT-5.6 Luna, and your current OpenAI default; add V4 Pro if harder tasks justify it. Route based on accepted-result cost, not provider loyalty.
Bottom Line
GPT-4.1 nano wins the raw token-price floor in this comparison. DeepSeek V4 Flash remains a strong output-heavy step up when nano fails your quality bar, especially during weekday off-peak hours or at any time on weekends, but the August 16 increase ended its automatic win over every small OpenAI model. V4 Pro is an evaluation candidate rather than a default budget escalation. Choose with the live rate table, your actual traffic schedule, and cost per accepted result.