---
title: DeepSeek V4.1 Flash Pricing vs Sonnet 5.5 and Opus 5.5
url: "https://goremy.ai/blog/articles/deepseek-v4-1-flash-pricing-vs-sonnet-opus"
author: Luis Chavez-Mattos
editor: Luis Chavez-Mattos
editor_title: Director, Product
published: "2026-10-27T02:20:07.223Z"
updated: "2026-10-30T16:54:37.249Z"
topic: AI Pricing & Usage Limits
description: DeepSeek V4.1 Flash costs 15 cents per million input tokens off-peak. Compare it with Sonnet 5.5 and Opus 5.5 on cached input, peak pricing and agent run costs.
---

# DeepSeek V4.1 Flash Pricing vs Sonnet 5.5 and Opus 5.5

> DeepSeek V4.1 Flash costs 15 cents per million input tokens off-peak. Compare it with Sonnet 5.5 and Opus 5.5 on cached input, peak pricing and agent run costs.

Edited by Luis Chavez-Mattos, Director, Product · Published 2026-10-27 · Updated 2026-10-30

## How much cheaper is DeepSeek V4.1 Flash than Sonnet 5.5 and Opus 5.5?

Off-peak, DeepSeek V4.1 Flash costs $0.15 per million input tokens, $0.60 per million output tokens and $0.003 per million cached input tokens. Sonnet 5.5 costs $2, $10 and $0.20 on the same three lines. That makes DeepSeek about 13x cheaper on input, about 17x on output and about 67x on cached input. Opus 5.5 is double Sonnet's prices, so the gap doubles again. DeepSeek's prices double at peak hours.

## TL;DR

- **Off-peak input and output** on DeepSeek V4.1 Flash run about 13x and 17x cheaper than Sonnet 5.5, and about 27x and 33x cheaper than Opus 5.5.
- **Cached input is the widest gap**, roughly 67x versus Sonnet and roughly 133x versus Opus, and cached reads make up most of an agent's tokens.
- **Peak pricing doubles** DeepSeek's rates, which cuts the advantage roughly in half but leaves it large.
- **One Sonnet 5.5 benchmark run cost $2.17.** At a conservative 13x ratio, the same work would cost around 16 to 17 cents on DeepSeek, though that run was never repeated on DeepSeek.
- **Price is not the whole story.** Opus 5.5 still does better on the hardest tasks, and your prompts go to DeepSeek's servers.

## What are the per-million-token prices?

These figures come from a creator's comparison of the three models. The Opus cached-input number is derived from the statement that Opus is double Sonnet across the board.

| Model | Input | Output | Cached input |
|---|---|---|---|
| DeepSeek V4.1 Flash (off-peak) | $0.15 | $0.60 | $0.003 |
| DeepSeek V4.1 Flash (peak) | $0.30 | $1.20 | $0.006 |
| Sonnet 5.5 | $2.00 | $10.00 | $0.20 |
| Opus 5.5 | $4.00 | $20.00 | $0.40 (derived) |

One note on the peak column. The source quotes peak output as "$120," but doubling $0.60 gives $1.20, so the transcript figure is almost certainly a transcription slip. The peak cached-input figure is also my arithmetic from "these prices double," not a quoted number. Check DeepSeek's current price sheet before you budget around either.

## How big is the gap in practice?

Here are the multipliers, calculated from the table above.

| Comparison | Input | Output | Cached input |
|---|---|---|---|
| Sonnet 5.5 vs DeepSeek off-peak | ~13x | ~17x | ~67x |
| Sonnet 5.5 vs DeepSeek peak | ~6.7x | ~8.3x | ~33x |
| Opus 5.5 vs DeepSeek off-peak | ~27x | ~33x | ~133x |
| Opus 5.5 vs DeepSeek peak | ~13x | ~17x | ~67x |

Even in the worst row for DeepSeek (Sonnet at peak), you pay roughly one-seventh to one-eighth as much on fresh tokens.

## Why does cached input matter most for agents?

An agent loop resends the same context on every turn. The system prompt, tool definitions, earlier file reads and earlier command output all get replayed. Providers bill those repeated tokens at the cached rate, so in a long session most of your volume lands on that line.

That is where DeepSeek's pricing is most lopsided. $0.003 per million against $0.20 means the repeated-context cost is close to negligible. If you run long, many-turn tasks, the cached rate will drive your bill more than the headline input price will. Those savings depend on cache hits, so it helps to know [how long DeepSeek keeps cached prompts](https://goremy.ai/blog/articles/deepseek-prompt-caching-how-long-and-cost) and how to keep your prefixes stable.

Context size still matters for another reason. One test in the source showed a reverse-engineering MCP server with 207 tools burning about 400,000 tokens on a single "okay" reply with all tools loaded. A lean skill file brought that to about 34,000. Cheap tokens do not excuse bloated context, because bloat also slows runs and eats turns.

## What does a real agent run cost?

The one concrete data point is a benchmark run for a reverse-engineering skill called LeanREA, tested with Sonnet 5.5. The whole run cost $2.17.

The creator had not yet run that benchmark on DeepSeek, and a different model will use a different number of tokens. Treat any projection as rough. Still, applying the most conservative ratio (13x, the input-price gap) gives about $0.16 to $0.17 for the same work. Because most of that spend is likely cached reads, where the gap is 67x, the real figure could be lower.

Two caveats from me, not the source:

- At peak rates, the same 13x logic gets you closer to 6.7x, or roughly 33 cents for that run.
- Max thinking effort tends to produce more output tokens. Output is DeepSeek's most expensive line, so a thinking-heavy run will skew your costs toward that side.

## What are the peak-hour catches?

DeepSeek V4.1 Flash prices change by time of day. Peak rates are double the off-peak rates on every line. The source does not say which hours count as peak, so look that up on DeepSeek's pricing page before scheduling anything.

The practical advice is simple. Batch jobs, benchmark sweeps and overnight refactors belong in the off-peak window. Interactive sessions you cannot move will cost twice as much, though still far less than Sonnet. Sonnet and Opus prices, as quoted, have no such split.

## Is DeepSeek V4.1 Flash good enough to replace Sonnet or Opus?

For many agent tasks, it looks capable. The creator reports 81.25% on Kingbench 3 with thinking at max, which placed it above their earlier V4 Pro result and level with Gemini 3.8 Flash. They also note DeepSeek trained it across many coding harnesses, including its own, which helps with tool use. For more scores against Opus 5 and GPT-5.6 Sol, see the [DeepSeek-V4.1-Flash-1017 benchmarks](https://goremy.ai/blog/articles/deepseek-v4-1-flash-1017-benchmarks).

The limits are real:

- **Hard problems.** Opus 5.5 still does better on the hardest tasks. Expect more turns or more guidance on deep problems.
- **Thinking effort.** With thinking off, the creator saw the score drop by almost 30 points. If you run it, set thinking to max, and budget for the extra tokens.
- **Data handling.** Your code and prompts go to DeepSeek's servers. Confirm that is acceptable before using it on private or company work.
- **Single-source claims.** The benchmark and cost figures come from one creator's tests, not an independent evaluation.

One more factor drove the original comparison. The creator said Claude Code and Codex had begun refusing certain reverse-engineering style prompts, while DeepSeek handled routine versions of that work without balking. Refusal behavior varies by task and changes over time, so test your own workload.

## How should you decide which model to run?

A sensible split follows the price and capability gaps:

1. Run high-volume, repetitive or long-context agent work on DeepSeek V4.1 Flash, off-peak when you can.
2. Keep Sonnet 5.5 for work where you want a stronger or more predictable model and the bill is manageable.
3. Escalate to Opus 5.5 for the hardest reasoning or debugging problems, where fewer failed turns can offset a price that is 27x to 133x higher per token.
4. Measure tokens per task on each model. Price per token only tells you the cost if token counts are similar, and they often are not.

## Frequently Asked Questions

### How much does DeepSeek V4.1 Flash cost per million tokens?

Off-peak, it costs $0.15 for input, $0.60 for output and $0.003 for cached input. At peak hours, each of those doubles. The source misquotes peak output as $120, but doubling gives $1.20.

### Is Opus 5.5 really double the price of Sonnet 5.5?

Per the source, yes. Sonnet 5.5 is $2 input and $10 output per million tokens, with cached input at $0.20. Opus 5.5 is $4 input and $20 output. The Opus cached rate was not stated directly, so $0.40 is inferred from the "double" claim.

### Will my agent bill really drop by 13x?

Not necessarily. 13x is the input-price ratio at off-peak, and the cached ratio is far higher, but total cost depends on how many tokens each model uses. The $2.17 Sonnet benchmark run was not repeated on DeepSeek, so the roughly 16 to 17 cent estimate is a projection.

### When is DeepSeek V4.1 Flash the wrong choice?

Skip it for very hard disassembly or reasoning problems where Opus 5.5 performs better. Also skip it if your code cannot leave your environment, since requests go to DeepSeek's servers. Running it with thinking off is a bad idea too, given the reported score drop of almost 30 points.