DeepSeek vs OpenAI: Price, Coding and Which to Use

DeepSeek is no longer the cheapest model API in this comparison. OpenAI's GPT-6 Luna costs $0.10 per million input tokens and $0.50 per million output tokens, which undercuts DeepSeek's deepseek-flash at both its off-peak and peak rates. DeepSeek still wins against OpenAI's top models by a wide margin: GPT-6 Astra output costs $50 per million tokens, against $1.20 for deepseek-flash at peak. This guide compares the two lineups on price, long-context billing, benchmarks, API compatibility and data handling, with every number taken from the vendors' own pages on October 7, 2026.

DeepSeek vs OpenAI at a glance

DeepSeek is a Chinese AI lab that sells its models through an OpenAI-compatible API. OpenAI is the US company behind ChatGPT and the GPT-6 model family. The table lists the current models on each side, with prices per million tokens.

	DeepSeek deepseek-flash	DeepSeek deepseek-v4-pro	OpenAI GPT-6 Luna	OpenAI GPT-6.1 Sol	OpenAI GPT-6 Astra
Role	Cheap, fast, multimodal	Larger text model	Cost-sensitive volume	Balanced	Most capable
Input, cache miss	$0.15-$0.30	$0.66-$1.32	$0.10	$2.00	$10.00
Input, cache hit	$0.003-$0.006	$0.022-$0.044	$0.01	$0.10	$1.00
Output	$0.60-$1.20	$1.98-$3.96	$0.50	$10.00	$50.00
Context window	1M	1M	1.05M	1.05M	1.05M
Max output	384K	384K	128K	128K	128K
Image input	Yes	No	Yes	Yes	Yes
Long-prompt surcharge	None listed	None listed	Yes, above 272K	Yes, above 272K	Yes, above 272K

DeepSeek ranges show off-peak first and peak second, because DeepSeek charges double on weekdays during fixed UTC hours. Sources: the DeepSeek pricing page, and OpenAI's pages for GPT-6 Luna, GPT-6.1 Sol and GPT-6 Astra.

How much cheaper is DeepSeek than OpenAI?

DeepSeek is 2 to 84 times cheaper than OpenAI's mid and top models, and slightly more expensive than GPT-6 Luna. The workload below is an agent that sends 100 million input tokens a month, serves 80% of them from cache, and generates 10 million output tokens.

Model	Cache hits (80M)	Cache misses (20M)	Output (10M)	Monthly total
OpenAI GPT-6 Luna	$0.80	$2.00	$5.00	$7.80
DeepSeek deepseek-flash, off-peak	$0.24	$3.00	$6.00	$9.24
DeepSeek deepseek-flash, peak	$0.48	$6.00	$12.00	$18.48
DeepSeek deepseek-v4-pro, off-peak	$1.76	$13.20	$19.80	$34.76
DeepSeek deepseek-v4-pro, peak	$3.52	$26.40	$39.60	$69.52
OpenAI GPT-6.1 Sol	$8.00	$40.00	$100.00	$148.00
OpenAI GPT-6 Astra	$80.00	$200.00	$500.00	$780.00

Four comparisons matter.

• Luna against Flash. Luna costs $7.80, which is 16% below Flash off-peak and 2.4 times below Flash at peak. If your task fits a small model, OpenAI is the cheaper vendor on list price.
• Flash against GPT-6.1 Sol. Sol costs $148, which is 8 times Flash at peak and 16 times Flash off-peak.
• Pro against Sol. V4-Pro at peak costs $69.52, so Sol is still 2.1 times more expensive than DeepSeek's dearest option.
• Flash against Astra. Astra costs $780, which is 42 times Flash at peak and 84 times Flash off-peak.

The table prices OpenAI cache writes at the normal input rate. OpenAI charges 1.25 times the input rate for cache writes, so real OpenAI totals run slightly higher. DeepSeek's price list shows no separate cache-write fee. OpenAI also offers Batch and Flex processing at 50% of standard rates, which halves the OpenAI rows for work that can wait. DeepSeek's equivalent is its off-peak rate, which is already in the table.

Price per token is only half the picture. For a method that compares models by finished task, see GPT-6 Sol vs Opus 5.5: cost per correct task, not per token, and for the wider argument, why the cheapest AI API is not the cheapest to run.

How do long prompts change the bill?

OpenAI reprices the whole request when the prompt passes 272,000 input tokens, and DeepSeek lists no such tier. For GPT-6 models, OpenAI states that prompts above 272K input tokens are priced at 2 times input and cache rates and 1.5 times output for the full request. The surcharge applies to every token in the request, not only the tokens above the threshold. Our breakdown of GPT-6 Astra's 272K cost cliff covers the mechanics in detail.

Here is what a single request costs with a 500,000-token prompt and a 5,000-token answer, with no cache hits.

Model	Input cost	Output cost	Request total
DeepSeek deepseek-flash, off-peak	$0.075	$0.003	$0.078
DeepSeek deepseek-flash, peak	$0.150	$0.006	$0.156
DeepSeek deepseek-v4-pro, off-peak	$0.330	$0.010	$0.340
DeepSeek deepseek-v4-pro, peak	$0.660	$0.020	$0.680
OpenAI GPT-6 Luna	$0.100	$0.004	$0.104
OpenAI GPT-6.1 Sol	$2.000	$0.075	$2.075
OpenAI GPT-6 Astra	$10.000	$0.375	$10.375

At 500K tokens the surcharge doubles Luna's input rate, so DeepSeek Flash is cheaper than Luna at off-peak and about 50% dearer at peak. Against Astra the gap is 66 to 133 times. Teams that feed whole repositories or long documents into one request feel this difference most. DeepSeek's pricing page lists a single rate for its 1M-token window, but confirm it before you depend on that for a large workload.

Is DeepSeek as good as OpenAI?

DeepSeek's published scores place V4.1-Flash behind GPT-6 Astra on the hardest agentic coding benchmark, and no verified like-for-like score exists for Luna against Flash. The comparison below uses figures each lab published about its own model, produced under different test setups, so read it as a rough map.

Benchmark	DeepSeek V4.1-Flash	OpenAI GPT-6 Astra
Terminal-Bench 4.0 (agentic coding)	31.2	57.9%

DeepSeek's score comes from its September 10 change log. The Astra score is the figure OpenAI reported, as reproduced in Anthropic's Claude Opus 5.5 announcement, because OpenAI's own page gives no number we could cite directly.

The comparison has limits you should know about.

1. Different test harnesses. DeepSeek used its own harness in minimal mode at maximum effort. OpenAI ran Astra at high effort. Scores from different harnesses can differ by several points.
2. Mismatched classes. V4.1-Flash is DeepSeek's smallest model in its new family, so Astra, OpenAI's flagship, is not its natural opponent. The closer pairing by price is Flash against Luna, and no verified benchmark covers it.
3. Vendor-run tests. Both labs wrote their own evaluations. Treat all of them as claims to check against your own data.

The practical advice is to build a 30 to 50 task evaluation from your real workload and run Flash, V4-Pro, Luna and Sol over it. A model that fails 20% of your tasks costs more than its price suggests, because every failure is a retry or a human fix.

Can you switch from OpenAI to DeepSeek without rewriting code?

Yes for most apps. DeepSeek's API accepts the OpenAI request format, so the OpenAI SDK works with a new base URL and model name. DeepSeek also lists support for the Responses API, JSON output and tool calls on both of its models, as the pricing page shows.

from openai import OpenAI

# OpenAI
openai_client = OpenAI(api_key="OPENAI_KEY")
r1 = openai_client.responses.create(model="gpt-6-luna", input="Summarise this changelog.")

# DeepSeek: same SDK, different base URL and model
deepseek_client = OpenAI(api_key="DEEPSEEK_KEY", base_url="https://api.deepseek.com")
r2 = deepseek_client.chat.completions.create(
    model="deepseek-flash",
    messages=[{"role": "user", "content": "Summarise this changelog."}],
)

Check these differences before you flip traffic.

• Reasoning controls differ. OpenAI exposes reasoning.effort levels such as low, medium, high, xhigh and max. DeepSeek uses its own thinking mode, which is on by default.
• Usage fields differ. DeepSeek reports prompt_cache_hit_tokens and prompt_cache_miss_tokens in usage. If your cost tracking reads OpenAI's cached-token fields, update it. See how AI SDK 7 changed usage reporting if you use that library.
• Per-user isolation. DeepSeek accepts a user_id parameter that isolates cache and scheduling per end user. Pass it through extra_body in the OpenAI SDK, as the rate limit guide shows.
• Concurrency caps. Accounts default to 2,500 concurrent requests on Flash and 500 on V4-Pro, and exceeding them returns HTTP 429.
• Retired OpenAI APIs. If you are still on older endpoints, note that the Assistants API shut down on August 26 and that GPT-4, o1 and o4-mini switch off on October 23. Those migrations are a natural moment to compare vendors.

A router can hide the differences. Whether to keep routing through OpenRouter after the Stripe acquisition is worth settling before you build on one.

How do data handling and compliance compare?

OpenAI offers documented data residency options and DeepSeek lists none on its pricing or rate-limit pages. OpenAI's data residency controls store customer content at rest in a chosen region, with a 10% price uplift on eligible models, and OpenAI lists US and EU residency for GPT-6.1 Sol and GPT-6 Luna, though Fast mode is not available with EU residency. Eligibility requires contacting OpenAI sales, and non-US regions require further approvals.

DeepSeek is a Chinese company. Regulated industries, government suppliers and anyone processing personal data under GDPR should read its privacy policy and take legal advice before sending customer data. DeepSeek publishes model weights on Hugging Face, so a team with the hardware may be able to self-host and keep data on its own network, subject to the model licence.

For the API-side retention question, read whether the free AI API tier trains on your data.

Which should you choose?

Choose by workload, not by brand. These recommendations assume you have checked quality on your own tasks.

Your situation	Start with	Why
High-volume, simple tasks where cost dominates	GPT-6 Luna, then deepseek-flash	Luna is cheapest on list price, Flash is close and has no long-prompt tier
Very long prompts above 272K tokens	deepseek-flash	Single rate, no whole-request repricing
Agent work that needs strong coding	GPT-6.1 Sol or Claude	DeepSeek's published coding scores trail the flagships
Hardest reasoning where failure is costly	GPT-6 Astra	Highest capability, but 42 to 84 times Flash cost
EU data residency requirement	OpenAI	Documented regional options
Want to self-host	DeepSeek	Published weights
Weekday work in Europe, India or East Asia	Compare against the peak column	Your working hours sit inside DeepSeek's peak window

If Anthropic is also on your shortlist, read DeepSeek vs Claude. If self-hosting appeals, the DeepSeek hardware requirements guide lists the GPUs involved. Most teams get the best result from two tiers. Send routine volume to the cheapest model that passes your tests, and escalate failures to a stronger one. Whichever vendor you pick, re-check the price pages every month, because lineups and rates in this market change often.

Sources

DeepSeek pricing, DeepSeek change log, DeepSeek V4.1-Flash release notes, OpenAI API pricing, OpenAI GPT-6 guide, OpenAI GPT-6 Luna, OpenAI GPT-6.1 Sol, OpenAI GPT-6 Astra, OpenAI data residency, Claude Opus 5.5 announcement.