TL;DR
Choose DeepSeek's API for a metered application; choose ChatGPT for a ready-to-use assistant. These are different purchases. DeepSeek charges for input and output tokens, with cache and time-of-day discounts. ChatGPT Plus is a $20/month consumer subscription with expanded tools and reasoning access; it does not include API credits. Start with a free chat account before buying either service.
What this comparison verifies
This is an official-documentation comparison, not a head-to-head performance benchmark. Pricing and plan descriptions were checked on October 8, 2026. We do not have a reproducible test set supporting numerical coding, reasoning or reliability rankings, so none are claimed here. Earlier uncited benchmark figures have been removed.
The important distinction is chat product versus developer API. A chat subscription pays for access inside a vendor's app, subject to feature-specific limits. An API bill depends on what your application sends and receives, including repeated context and reasoning output. Neither is interchangeable with running a model yourself.
Current pricing snapshot
| Product | Published price | What the bill measures |
|---|---|---|
| ChatGPT Free | $0 | Consumer app access; tool and context limits apply |
| ChatGPT Go | $8/month | Expanded consumer app access |
| ChatGPT Plus | $20/month | Expanded reasoning, uploads, research and Codex usage |
| ChatGPT Pro | From $100/month | Higher consumer usage tiers |
| DeepSeek Flash API | See token table below | Input, output, cache status and peak/off-peak time |
| DeepSeek Pro API | See token table below | Separate rates from Flash |
Prices are the USD figures displayed by the official sources. Taxes, regional offers and checkout terms can differ. OpenAI's current page describes GPT-5.6 Luna access on Free and GPT-6 reasoning access on Plus; this is not a comparison of the older GPT-4o and DeepSeek v3 models.
DeepSeek API: rates per one million tokens
| Model | Cached input, off-peak / peak | Uncached input, off-peak / peak | Output, off-peak / peak |
|---|---|---|---|
deepseek-flash |
$0.003 / $0.006 | $0.15 / $0.30 | $0.60 / $1.20 |
deepseek-v4-pro |
$0.022 / $0.044 | $0.66 / $1.32 | $1.98 / $3.96 |
The documentation identifies Flash as DeepSeek-V4.1-Flash and Pro as DeepSeek-V4-Pro-0813. Peak hours are 01:00–04:00 and 06:00–10:00 UTC on weekdays, excluding Chinese public holidays. Check the source again before estimating production spend; these rates can change.
A worked cost example, not a measured workload
Assume 1,000 Flash API requests in a day, each with 500 uncached input tokens and 300 output tokens. That is 0.5 million input and 0.3 million output tokens:
- Off-peak:
(0.5 × $0.15) + (0.3 × $0.60) = $0.255/day. - Peak:
(0.5 × $0.30) + (0.3 × $1.20) = $0.51/day. - Thirty identical days: approximately $7.65–$15.30 before other application costs.
This is arithmetic under stated assumptions. Real prompts may carry much longer histories; output length and reasoning use vary. It does not show that a $20 chat subscription can serve an automated application or that either model has equivalent answer quality.
Which workflow should you choose?
Choose ChatGPT when the app is the product you need. Its pricing page lists uploads, search, voice, data analysis and projects, with different access levels by plan. Plus adds expanded reasoning, research and coding usage. Buying Plus for those features can make sense without building your own interface.
Choose DeepSeek's API when you are building the workflow yourself. Its docs list tool calls, JSON output and OpenAI-format endpoints, along with model-specific capabilities. Budget for integration, logging, retries and reviewing outputs. Low token prices alone do not settle whether it fits your task.
For coding, compare one bug fix on your own repository and run its tests. For factual research, inspect source links and dates. For long documents, check whether quotations remain accurate. Save the prompts and outputs before claiming one is better.
Verdict: Choose by product, not an uncited benchmark
ChatGPT Plus is a consumer workflow subscription; DeepSeek's API is metered developer access. Use the free app for casual work and a small, capped API workload for integration testing. Neither price alone proves a performance winner.
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