TokenMix Research Lab · 2026-04-24

Claude 3.7 Sonnet Pricing 2026: Retired, Upgrade To 4.6

Claude 3.7 Sonnet Pricing 2026: Retired, Upgrade To 4.6

Last Updated: 2026-04-30
Author: TokenMix Research Lab
Data checked: 2026-04-30

Claude 3.7 Sonnet is retired on the Claude API. Do not price new workloads on 3.7. Upgrade to Claude Sonnet 4.6 unless you have a specific 4.5 regression reason.

The old 3.7 pricing question used to matter because Claude 3.7 Sonnet introduced hybrid reasoning at $3/$15 per million tokens. But Anthropic's current model deprecations page lists claude-3-7-sonnet-20250219 as retired, with retirement on February 19, 2026. It also lists claude-sonnet-4-6 as the recommended replacement for retired Sonnet 3.7 and older Sonnet models. So the real 2026 answer is not "is 3.7 still worth it?" It is "how do I migrate with the least quality, cost, and behavior risk?"

Table of Contents

Quick Verdict

Do not start any new work on Claude 3.7 Sonnet. It is retired. Migrate old API calls to Sonnet 4.6, then reserve Opus 4.7 only for tasks where Sonnet fails.

Situation Best action Why
New app Use claude-sonnet-4-6 Current recommended Sonnet route
Old 3.7 API code Migrate to 4.6 3.7 is retired
Need exact old behavior for audit Keep old outputs, not old API dependency Retired model is not a stable production path
Worried 4.6 changes style A/B against 4.5 and 4.6 4.5 is active longer than 3.7, but 4.6 has longer runway
Hard reasoning/coding still fails on Sonnet Route to Opus 4.7 Higher cost, higher capability
Cost-sensitive simple tasks Route to Haiku 4.5 or cheaper model Sonnet is not needed for every step

Confirmed Status

Model Current API state Tentative retirement signal Recommended reading
claude-3-7-sonnet-20250219 Retired Retired February 19, 2026 Do not use for new or production API calls
claude-sonnet-4-20250514 Deprecated Retires June 15, 2026 Migrate before the cutoff
claude-sonnet-4-5-20250929 Active Not sooner than September 29, 2026 Use for regression only if needed
claude-sonnet-4-6 Active Not sooner than February 17, 2027 Default Sonnet upgrade target
claude-opus-4-7 Active Not sooner than April 16, 2027 Premium fallback for hardest tasks
claude-haiku-4-5-20251001 Active Not sooner than October 15, 2026 Low-cost route for simple tasks

This table should replace any old rule of thumb about "18-month support" or "safe through 2027." Use the official deprecation page, not lifecycle guesses.

Historical 3.7 Pricing vs Current Sonnet Pricing

Claude 3.7 Sonnet launched with the same Sonnet price band that later Sonnet releases kept: $3 per million input tokens and $15 per million output tokens. That historical fact is useful for migration math, but not for choosing 3.7 today.

Model Price signal Current status What it means now
Claude 3.7 Sonnet Historical $3/$15 per MTok Retired Do not budget new traffic here
Claude Sonnet 4.5 $3/$15 per MTok Active Shorter runway than 4.6
Claude Sonnet 4.6 $3/$15 per MTok Active Best default upgrade
Claude Haiku 4.5 $1/$5 per MTok Active Cheaper for simple work
Claude Opus 4.7 $5/$25 per MTok Active Higher-cost premium fallback

The important point: moving from 3.7 to Sonnet 4.6 does not change the headline Sonnet price band. It changes model behavior, support runway, and available features.

Upgrade Target: 4.6 vs 4.5 vs Opus

The correct replacement is usually Sonnet 4.6. Sonnet 4.5 is a temporary compatibility target. Opus 4.7 is a premium escalation target, not the default replacement for every 3.7 call.

Target Use when Avoid when
Sonnet 4.6 New default, coding, agents, analysis, app backends You need exact 4.5 behavior for a known regression
Sonnet 4.5 Regression shows 4.6 changes output in a harmful way New projects or long runway needs
Opus 4.7 Hard reasoning, difficult code review, high-value agent tasks Classification, extraction, routine chat
Haiku 4.5 Fast low-cost routing, pre-processing, simple extraction Deep reasoning or complex code generation
Multi-model gateway You need fallback, cost routing, or A/B testing You only need one fixed first-party model

For broader routing logic, see our Claude Sonnet vs Opus guide and Claude Haiku vs Sonnet guide.

Migration Steps

Do not migrate by changing a model name and hoping. Retired-model migrations deserve a small regression set.

Step Action Why
1 Search code and config for claude-3-7-sonnet-20250219 and aliases Find every old route
2 Capture 20 to 50 real prompts Generic prompts miss production drift
3 Run Sonnet 4.6 against the set Establish replacement behavior
4 Compare task success, not vibes The model can sound different while solving better
5 Check output length and token cost Same price band can still produce different token usage
6 Update fallback chains Avoid falling back to retired or deprecated models
7 Monitor 429/529 and latency Production behavior matters

Minimal code change:

from anthropic import Anthropic

client = Anthropic(api_key="your-anthropic-api-key")

message = client.messages.create(
    model="claude-sonnet-4-6",
    max_tokens=800,
    messages=[{"role": "user", "content": "Run the migrated prompt."}],
)

print(message.content[0].text)

If you use a gateway such as TokenMix.ai, run the same regression set through Sonnet 4.6, Sonnet 4.5, Haiku 4.5, Opus 4.7, and non-Claude fallback models. The right default is the model with the lowest cost per successful task, not necessarily the model with the highest benchmark score.

Extended Thinking Migration

Claude 3.7 Sonnet mattered historically because it introduced hybrid reasoning: normal answers or extended thinking with a controllable thinking budget. Newer Claude models also support thinking modes, but you should still test cost and output behavior.

3.7-era behavior Migration check
Thinking tokens billed as output Confirm current model pricing and output budget
Large thinking budgets for math/code Re-test whether Sonnet 4.6 needs the same budget
Long reasoning chains Watch latency and OTPM pressure
Tool-heavy agent prompts Re-test tool choice and stop conditions
Prompt tuned for 3.7's style Remove unnecessary scaffolding if 4.6 follows better

Do not blindly carry over huge thinking budgets. If Sonnet 4.6 solves the task with less reasoning budget, keep the savings.

Cost Math

Assume 100 million input tokens and 30 million output tokens per month.

Route Input cost Output cost Monthly cost Notes
Historical 3.7 Sonnet band $300 $450 $750 Retired; use only as baseline
Sonnet 4.6 $300 $450 $750 Default replacement
Sonnet 4.5 $300 $450 $750 Active but shorter runway
Haiku 4.5 $100 $150 $250 Good for simple tasks
Opus 4.7 $500 $750 $1,250 Premium escalation
70% Haiku + 25% Sonnet + 5% Opus Mixed Mixed About $425 Routing can beat one-model defaults

The migration opportunity is not "save money by keeping 3.7." That path is gone. The opportunity is to route tasks more intelligently after migration.

When 4.5 Still Makes Sense

There are narrow cases where 4.5 is a better intermediate step than 4.6.

Case Why 4.5 may help
4.6 changes a strict output format 4.5 may be closer to old behavior
Creative style regression Some workflows value old tone
Compliance validation takes months 4.5 is active and buys time
Historical benchmark continuity 4.5 is closer to the old generation than 4.6
Gateway currently exposes 4.5 but not 4.6 Temporary route only

But for new work, 4.5 should not become the new long-term default. It has a shorter listed support runway than 4.6.

What Not To Do

Bad idea Why
Keep recommending 3.7 as stable It is retired on the Claude API
Compare 3.7 benchmarks as if it is buyable today Historical data does not equal current availability
Migrate to 4.5 by default 4.6 is the recommended replacement for retired Sonnet 3.7
Ignore deprecation docs Blog guesses age badly
Route fallback to Sonnet 4 Sonnet 4 is already deprecated with a June 15, 2026 retirement date
Treat Opus as a drop-in replacement for all 3.7 traffic It is materially more expensive

Final Recommendation

Claude 3.7 Sonnet pricing is now historical. Replace 3.7 with Sonnet 4.6, keep Sonnet 4.5 only for regression exceptions, and use TokenMix.ai routing to send easy work to cheaper models.

FAQ

Is Claude 3.7 Sonnet deprecated or retired?

It is retired on the Claude API. Anthropic's model deprecation page lists claude-3-7-sonnet-20250219 as retired, with retirement on February 19, 2026.

What should I replace Claude 3.7 Sonnet with?

Use claude-sonnet-4-6 for most workloads. Anthropic lists Sonnet 4.6 as the recommended replacement for retired Sonnet 3.7 and older Sonnet models.

Was Claude 3.7 Sonnet priced at $3/$15 per million tokens?

Yes historically. Anthropic's 3.7 launch said it had the same price as its predecessors: $3 per million input tokens and $15 per million output tokens, including thinking tokens.

Does moving to Sonnet 4.6 increase headline price?

No, not at the starting Sonnet API price band. Sonnet 4.6 is also priced at $3/$15 per million tokens. Output length and prompt behavior can still change effective cost.

Should I migrate to Sonnet 4.5 first?

Usually no. Use Sonnet 4.6 unless your regression tests show a specific 4.6 behavior problem. Sonnet 4.5 has a shorter listed support runway.

Does extended thinking still matter after 3.7?

Yes, but re-test budgets. Newer Claude models may solve some tasks with different thinking settings, and large reasoning budgets can raise output cost and latency.

Can TokenMix.ai help with 3.7 migration?

Yes. Use TokenMix.ai to A/B Sonnet 4.6, Sonnet 4.5, Haiku, Opus, and non-Claude fallback models through one API surface, then route by task type and cost per successful output.

What if my app requires exact 3.7 outputs?

Archive old outputs for audit, but do not rely on retired live API availability. Build a regression suite and choose the closest active replacement.

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