AI Translation Service Cost — 1M Words/Month at Production Scale
Translating 1M words per month (roughly 1.3M tokens) runs $15–$280 — translation is one of the cheapest LLM workloads.
Scenario
An app provides on-demand translation between English and a dozen other languages. Users translate 1 million words per month (about 1.3M input tokens, growing to ~2.6M including the translated output of similar length). Each request is small (under 1k tokens). The work is mildly latency-sensitive (under 2 seconds) but tolerates batching for bulk imports.
| Assumption | Value |
|---|---|
| Words / month | 1,000,000 (~1.3M tokens) |
| Input:output ratio | ~1:1 (translated text ≈ source length) |
| Cache hit | 10% (only shared system prompt) |
| Latency | Under 2 seconds (interactive UI) |
Translation has near-1:1 input/output ratio (unusual — most workloads are input-heavy). Models with cheap output pricing win here.
Monthly cost across recommended models
Calculated at 1M input tokens + 1.3M output tokens, with 10% prompt cache hit rate.
| Model | Input cost | Output cost | Cache savings | Total / mo |
|---|---|---|---|---|
| Deepseek Chat Cheapest | $0.36 | $0.55 | −$0.03 | $0.88 |
| Gpt 5 Mini | $0.33 | $2.60 | −$0.03 | $2.90 |
| Gemini 2.5 Flash | $0.39 | $3.25 | −$0.04 | $3.60 |
| Claude Haiku 4 5 | $1.30 | $6.50 | −$0.12 | $7.68 |
💡 Switching from Claude Haiku 4 5 to Deepseek Chat saves $6.81/month (89% reduction).
Why these models
Translation rewards models that are cheap on BOTH input and output. DeepSeek dominates on pure cost. GPT-5 Mini is the safest pick if you need strong translation quality for less-common language pairs. Claude Haiku is fast. Gemini Flash offers broad language coverage.
Key insights
- 1. Output cost matters more here than for any other workload — a 5× difference in output pricing translates directly to the bill.
- 2. Specialized translation models (NLLB, M2M-100) self-hosted can be 10× cheaper but quality varies by language pair. Evaluate before switching.
- 3. Cache the system prompt ("translate {source} to {target}, keep formatting...") aggressively. Even at 10% hit rate it saves real money at volume.
- 4. For very low-resource languages (Pashto, Yoruba, etc.) GPT-5 and Claude Opus still significantly outperform Mini-tier — sometimes worth the 6× cost.
Cost at different scales
| Scale | Deepseek Chat | Gpt 5 Mini | Gemini 2.5 Flash | Claude Haiku 4 5 |
|---|---|---|---|---|
| Hobby project (100k words) | $0.09 | $0.29 | $0.36 | $0.77 |
| Baseline (1M words) | $0.88 | $2.90 | $3.60 | $7.68 |
| SaaS scale (10M words) | $8.77 | $28.96 | $36.05 | $76.83 |
| Localization platform (100M words) | $87.72 | $290 | $360 | $768 |
Try your own scenario
The numbers above use our best-guess assumptions. For your actual workflow, use the interactive calculator to plug in your real token volumes and quality requirements.
All cost figures are estimates based on publicly-listed pricing as of the data refresh date. Verify with the provider's official pricing page before making business decisions. Embedding costs, vector database costs, and infrastructure costs are not included unless explicitly noted.