API cost decision in 10 seconds

🔥DeepSeek V4 Flash vs 🔥GLM 5.1

Pick DeepSeek V4 Flash when budget and context both matter.

Pricing data updated:  Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick DeepSeek V4 Flash when budget and context both matter.

On the standard 1M input plus 500K output workload, DeepSeek V4 Flash is estimated at $0.25 vs $2.52 for GLM 5.1, saving $2.27 (90% lower).

Cost-first pickDeepSeek V4 Flash
Context-first pickDeepSeek V4 Flash
Sample savings$2.2790%
10x traffic gap$22.68

DeepSeek V4 Flash is cheaper on the standard workload and also has the larger context window. At 10x that traffic, the same price gap is about $22.68. Use the calculator below to replace the sample workload with your own token volume.

Cheaper input DeepSeek V4 Flash $0.126 vs $0.98 / 1M

DeepSeek V4 Flash is $0.85 cheaper per 1M input tokens (87.1% lower; 7.78x difference).

Cheaper output DeepSeek V4 Flash $0.252 vs $3.08 / 1M

DeepSeek V4 Flash is $2.83 cheaper per 1M output tokens (91.8% lower; 12.2x difference).

Larger context DeepSeek V4 Flash 1.05M vs 202.75K

DeepSeek V4 Flash has 845.82K more context (5.17x larger).

Sample workload DeepSeek V4 Flash $0.25 vs $2.52

DeepSeek V4 Flash is $2.27 cheaper on the standard workload (90% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.
DeepSeek V4 Flash Calculating… Estimated API cost
GLM 5.1 Calculating… Estimated API cost
Cheaper for this workload Calculating… Difference: calculating…

This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.

Quick Decision

Verdict

DeepSeek V4 Flash has the lower input price; DeepSeek V4 Flash has the lower output price; DeepSeek V4 Flash offers the larger context window. For the 1M input plus 500K output sample, DeepSeek V4 Flash is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $0.25 for DeepSeek V4 Flash and $2.52 for GLM 5.1.

Best Fit

Choose DeepSeek V4 Flash when you care most about lower input-token price, lower output-token price, and larger context window.

Choose GLM 5.1 when its provider, model quality, latency, or availability is more important than the numeric price/context winner.

Decision Notes
  • On the standard 1M input plus 500K output workload, DeepSeek V4 Flash is estimated at $0.25 vs $2.52 for GLM 5.1, saving $2.27 (90% lower).
  • DeepSeek V4 Flash is $2.27 cheaper on the standard workload (90% lower).
  • DeepSeek V4 Flash is $0.85 cheaper per 1M input tokens (87.1% lower; 7.78x difference).
  • DeepSeek V4 Flash is $2.83 cheaper per 1M output tokens (91.8% lower; 12.2x difference).
  • DeepSeek V4 Flash has 845.82K more context (5.17x larger).
Head-to-Head Specs
Feature🔥DeepSeek V4 Flash
(DeepSeek)		🔥GLM 5.1
(Z.ai)
Input Price
prompt tokens per 1M		$0.126$0.98
Completion Price
per 1M tokens		$0.252$3.08
Sample Workload Cost
1M input + 500K output		$0.25$2.52
Context Window1.05M202.75K
Release Date
Popularity Rank
current rank		#4#20

Use-Case Decision Matrix

Use caseBetter pickWhy
Budget-constrained productionDeepSeek V4 FlashOn the standard 1M input plus 500K output workload, DeepSeek V4 Flash is estimated at $0.25 vs $2.52 for GLM 5.1, saving $2.27 (90% lower).
High-volume input processingDeepSeek V4 FlashLower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbotsDeepSeek V4 FlashLower output-token price matters most when assistants generate many completion tokens.
RAG or long-document workDeepSeek V4 FlashA larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps
  • DeepSeek V4 Flash (free) can replace DeepSeek V4 Flash when lower sample workload cost matters most: $0.
  • GLM 4.5 Air (free) can replace GLM 5.1 when lower sample workload cost matters most: $0.
  • GLM 4 32B can replace GLM 5.1 when lower sample workload cost matters most: $0.15.
  • GLM 4.7 Flash can replace GLM 5.1 when lower sample workload cost matters most: $0.26.
Larger context near this budget
  • Grok 4.1 Fast offers 2M context with $0.45 sample workload cost.
  • Grok 4.20 offers 2M context with $2.5 sample workload cost.
  • Grok 4 Fast offers 2M context with $0.45 sample workload cost.
  • Owl Alpha offers 1.05M context with $0 sample workload cost.

Cheaper alternatives

Review low-cost models ranked by a standard 1M input plus 500K output workload.

Open cheapest models

Larger context alternatives

Find models with larger context windows for RAG, long documents, and codebase review.

Open largest context models

Provider catalogs

Compare models within provider hubs before choosing a final API vendor.

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DeepSeek catalog

Review all tracked DeepSeek models before deciding whether this matchup is the right shortlist.

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Z.ai catalog

Check other Z.ai models with comparable pricing, context, or release timing.

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DeepSeek V4 Flash

DeepSeek V4 Flash is an efficiency-optimized Mixture-of-Experts model from DeepSeek with 284B total parameters and 13B activated parameters, supporting a 1M-token context window. It is designed for fast inference and...

GLM 5.1

GLM-5.1 delivers a major leap in coding capability, with particularly significant gains in handling long-horizon tasks. Unlike previous models built around minute-level interactions, GLM-5.1 can work independently and continuously on...