GPT-4o vs. GPT-5: API Cost Comparison

On this API, GPT-4o costs $0.875 / $3.5 per 1M tokens (in/out) and GPT-5 costs $0.4375 / $3.5. GPT-5 is the cheaper option, and both run on the same key — switching is a one-line model parameter change.

Get an API key All model prices

Per-token pricing

	GPT-4o	GPT-5
Vendor	OpenAI	OpenAI
Input · per 1M tokens · Official list	$2.5	$1.25
Input · per 1M tokens · Your price	$0.875	$0.4375
Output · per 1M tokens · Official list	$10	$10
Output · per 1M tokens · Your price	$3.5	$3.5
Discount vs. list	-65%	-65%
Context window	128K tokens	400K tokens
Max output tokens	16K tokens	128K tokens

All prices in USD per 1M tokens.

What a real workload costs

Same request stream priced on both models — 10M input + 2M output tokens per month, a typical coding-agent load:

GPT-4o

At official list: $45 per month
On this API: $15.75 per month

GPT-5

At official list: $32.5 per month
On this API: $11.38 per month

Switching between them

Both models answer on the same endpoint. Keep your base URL and key; change only the model parameter to reroute a request:

model="gpt-4o"

curl https://kktt.net/v1/chat/completions \
  -H "Authorization: Bearer $API_KEY" \
  -d '{"model": "gpt-4o", "messages": [...]}'

model="gpt-5"

curl https://kktt.net/v1/chat/completions \
  -H "Authorization: Bearer $API_KEY" \
  -d '{"model": "gpt-5", "messages": [...]}'

FAQ

Which is cheaper, GPT-4o or GPT-5?

On this API, GPT-5 is cheaper: $0.4375 in / $3.5 out per 1M tokens, versus $0.875 in / $3.5 out for GPT-4o.

Can I use GPT-4o and GPT-5 with the same API key?

Yes. Both are callable with one key on the same base URL — switching between them is a one-line change of the model parameter, which makes A/B testing or fallback routing trivial.

Do GPT-4o and GPT-5 differ in context window?

GPT-4o supports 128K of context with 16K max output; GPT-5 supports 400K with 128K max output.