Muse Spark 1.1 vs GPT-5.6 Terra vs Grok 4.20

Muse Spark 1.1 at $1.44 in and $4.89 out, GPT-5.6 Terra at $1.15 in and $6.90 out, and Grok 4.20 at $1.44 in and $2.88 out — per million tokens, from the same wallet.

Muse Spark 1.1

At a glance

Cheapest input: GPT-5.6 Terra at $1.15 per million tokens.
Cheapest output: Grok 4.20 at $2.88 per million tokens.
Largest context: Grok 4.20 at 2M tokens — about 2,900 pages.

Cost per task

Estimated totals at the rates above. Solid bar is input, lighter bar is output.

Quick code fix

2K in · 500 out

Muse Spark 1.1

0.53¢

GPT-5.6 Terra

0.57¢

Grok 4.20

0.43¢

Draft a client proposal from notes

5K in · 800 out

Muse Spark 1.1

1.1¢

GPT-5.6 Terra

1.1¢

Grok 4.20

0.95¢

Context-heavy session (Alyph workspace)

155K in · 4K out

Muse Spark 1.1

$0.24

GPT-5.6 Terra

$0.21

Grok 4.20

$0.23

Analyze a 50-page legal contract

35K in · 1K out

Muse Spark 1.1

$0.06

GPT-5.6 Terra

4.7¢

Grok 4.20

$0.05

Large architecture refactor

250K in · 3K out

Muse Spark 1.1

$0.37

GPT-5.6 Terra

$0.31

Grok 4.20

$0.74

Long-context rate applied at this input size.

Solid part of each bar is input tokens, the lighter part is output. Models that don’t fit a task are marked instead of priced.

Cost vs Token Amount

Drag the slider to adjust the split between input and output workload.

80% Input20% Output

Muse Spark 1.1

GPT-5.6 Terra

Grok 4.20

Adjust the ratio slider to change how output tokens influence the final price for equivalent workloads.

Pricing

Muse Spark 1.1

GPT-5.6 Terra

Grok 4.20

Input / 1M tokens

$1.44

$1.15

$1.44

Output / 1M tokens

$4.89

$6.90

$2.88

Cached input / 1M

$0.172

$0.115

$0.230

Web search

0.29¢ / search

0.57¢ / search

Specs

Muse Spark 1.1

GPT-5.6 Terra

Grok 4.20

Provider

Try it with real numbers

2K tokens in · 500 tokens out.

Muse Spark 1.1

Which should you pick?

For long documents, Grok 4.20 has the largest context window here — 2M tokens.

On price, Grok 4.20 is the cheapest of the three on a typical task, at about 0.95¢.

Or don’t pick. Send the identical prompt to all three, read the answers side by side, and keep the winner. How to run a fair bake-off →

Muse Spark 1.1 pricing →GPT-5.6 Terra pricing →Grok 4.20 pricing →Try other combinations →

Questions, answered

Which is cheapest — Muse Spark 1.1, GPT-5.6 Terra, or Grok 4.20?

On a typical client proposal (5K tokens in, 800 out): Grok 4.20 at 0.95¢; Muse Spark 1.1 at 1.1¢; GPT-5.6 Terra at 1.1¢. Long prompts can change the order when long-context rates apply.

Which has the largest context window?

Grok 4.20 — 2M tokens, about 2,900 pages.

Can I run Muse Spark 1.1, GPT-5.6 Terra, and Grok 4.20 side by side on Alyph?

Yes — that is what Alyph is built for: the identical prompt with identical context to all 3, answers rendered side by side, billed from one wallet. This exact combination costs about 3.2¢ for a typical task.

Ask all three at once

Identical prompt, identical context, answers side by side — about 3.2¢ for a typical client proposal. Free to start, with $5 of credit.