Cost

DeepSeek's headline feature is a disk-backed context cache that makes a repeated prompt prefix roughly fifty times cheaper. That saving is invisible unless something is counting — so this counts.

The rate card

USD per 1M tokens, as published on 2026-08-02:

ds models prints this next to the live model list, so the price is on screen when you pick.

What the cache is worth

On flash, a cache hit costs 1/50th of a miss. The same 3,200-token prompt, sent twice:

$ ds chat "..." --system @prefix.txt
one
· flash · 3.2k in · 1 out · ~$0.000450 · 0.84s

$ ds chat "..." --system @prefix.txt
two
· flash · 3.2k in (100% cached) · 1 out · ~$0.000011 · 1.04s

A 40× drop, for changing nothing but sending the same prefix again. The practical rule: put the stable part of a prompt first — same system prompt, same files, in the same order — and let the variable part come last.

The thinking surcharge

Thinking mode is on by default and adds a fixed template to your input before generating a single reasoning token. The size of that template is constant regardless of prompt length — but it is not the same at every effort level, and at the low levels it is not there at all while the model still reasons.

Two of those levels are in no DeepSeek documentation at all. none is documented only for the Responses API, but the chat endpoint takes it and it disables thinking exactly as --think off does. minimal is undocumented everywhere. The API rejects only genuinely unknown values, with unknown variant, which is how this list was established.

The practical consequence: on flash, --effort low removes the entire input surcharge and keeps the chain of thought. On a short factual lookup at the default effort, that template is most of the bill.

ds tokens "your prompt here"           # what it costs at default effort
ds tokens "your prompt here" -e low    # what it costs without the template

The ledger

Every call prints one line to stderr and appends one row to ~/.local/state/deepseek/usage.jsonl:

{"ts":"2026-08-05T05:18:12Z","api":"chat","model":"deepseek-v4-flash",
 "in":3242,"cache_hit":3200,"cache_miss":42,"out":1,
 "cost_usd":0.0000109,"saved_usd":0.000439,"ms":1041}

Token counts are exact and are what gets stored; the cost field is a convenience. That is deliberate — when DeepSeek changes the rate card, every historical row can be repriced.

ds usage                  # today
ds usage --since 7d
ds usage --since all --json
ds usage --entries        # individual calls

                   CALLS  IN     CACHED  OUT    COST
deepseek-v4-flash  184    2.1M   78%     94k    $0.19
deepseek-v4-pro    12     88k    41%     11k    $0.03
total              196    2.2M   77%     105k   $0.22

by format: chat 170, anthropic 14, responses 8, fim 4
context cache saved ~$0.23 (1.7M of 2.2M prompt tokens replayed)
costs are estimates from the published USD rate card, not billed amounts

The savings line is the one worth watching. It is what the cached tokens would have cost at the miss rate, minus what they did cost — which is the number that tells you whether prompt structuring is paying off.

What these numbers are not

--no-ledger skips the write, --no-stats hides the line, and neither ever fails the command that produced it — you asked for a completion, not for bookkeeping.