AI vs MT: Auto-translation comparison with examples
Auto-translation services have become essential tools for breaking down language barriers in today's world. Among the most popular providers are DeepL, Google Translate, and OpenAI. In this post, we'll look at how each of these platforms handles translations, analyze examples, compare results, and assess the cost of translation.
If you want the broader framework behind these provider choices, start with our complete AI and machine translation guide.
What is machine translation?
Machine translation is the process of automatically translating text from one language to another using computer software. It's a powerful tool that can help translate large volumes of text quickly and efficiently, making it easier to communicate across language barriers.
Machine translation is widely used in various industries, including software localization, e-commerce, and travel, to help businesses reach a global audience.
It uses algorithms to analyze the structure of a sentence in one language and generate an equivalent sentence in another language. These algorithms can be rule-based, statistical, or neural network-based, with each approach having its own strengths and weaknesses.
Common issues with machine translation
While machine translation has come a long way in recent years, it still has some limitations. Here are a few common issues you might encounter when using machine translation:
- Accuracy: Machine translation systems can struggle with idiomatic expressions, slang, and other nuances of language.
- Context: They don't always take context into account, which can lead to errors in translation.
- Tone: Capturing the tone and style of a text can be difficult, affecting the overall quality of the translation.
- Domain-specific terminology: They may not be able to accurately translate specialized terminology used in specific fields, such as medicine or law.
- Language pairs: Not all language pairs are supported, limiting their usefulness in certain situations.
Auto-translation examples
To illustrate how DeepL, Google Translate, and OpenAI handle translations, let's look at some examples. We will translate a few simple phrases from English to Spanish and Polish using each of these platforms. Our texts come from a hotel website and include common phrases that you might encounter when traveling, thus providing a good test of the platforms' capabilities.
Here are our translation keys with text in English:
Auto-translation will be performed using the SimpleLocalize translation editor, integrated with DeepL, Google Translate, and OpenAI.
Auto-translation using DeepL
DeepL is a popular machine translation service known for its high-quality translations. It was created by Jarosław Kutylowski, a Polish entrepreneur, and is based on deep learning technology that can generate accurate translations in multiple languages. The main advantage of DeepL is its ability to produce natural-sounding translations that are close to human quality.
Let's see how DeepL handles our example phrases when translated into Spanish and Polish.
Auto-translation to Spanish:
Auto-translation to Polish:
The translations are accurate and natural in both Spanish and Polish. DeepL has done a good job of capturing the meaning of the original English text and producing high-quality translations.
For better results, you can use additional options provided by DeepL, such as glossary, context, and using key description for additional context when translating with SimpleLocalize.
- Glossary - a predefined list of terms and translations that can be used by DeepL to improve translation quality. Learn more about the DeepL glossary
- Context - additional information about the translated text, like format, style, or purpose
- Description - translation key description that can provide additional context for the specific translation
Auto-translation using Google Translate
Google Translate is one of the most widely used machine translation services, offering translations in over 249 languages. It uses neural machine translation to generate translations, and in 2025 Google upgraded its models with Gemini-powered quality improvements.
Let's see how Google Translate translates our texts into Spanish and Polish.
Auto-translation to Spanish:
Auto-translation to Polish:
At first glance, the translations seem accurate, but there are some issues. For example, the term "Executive lounge" was translated to Polish as "Salon wykonawczy" which is not accurate; such a term doesn't exist in Polish. The correct translation should be "Sala VIP", "Salon Executive" or "Sala Executive".
Auto-translation using OpenAI
OpenAI is a leading provider of AI technology that can be used for machine translation. It offers a range of language models that can generate high-quality translations in multiple languages. OpenAI's translation models are based on deep learning and can produce accurate translations that are close to human quality.
Let's see how OpenAI handles our translations to Spanish and Polish.
Auto-translation to Spanish:
Auto-translation to Polish:
We can see that only OpenAI retained the original term "Pillow Menu" as its own name, although translated. All translations are accurate and natural in both Spanish and Polish.
Similar to DeepL, OpenAI provides additional options that can be used to improve translation quality, like context and key description.
Comparison
Let's gather all the translations in one place and compare them side by side.
English to Spanish:
English to Polish:
Observations
All three platforms produced accurate translations in both Spanish and Polish for simpler, more general phrases, like Do not disturb or Welcome amenities. However, we can see how differently they approach the translation of texts whose translations are not that straightforward, like Room service in Polish.
- DeepL uses more natural language compared to Google Translate and OpenAI, especially for longer phrases.
Late check-out: all platforms translated the term correctly, but to make it more natural, it could be left as-is in English, as it's a term that can be understood in many languages.- All services translated
Pillow Menurather than keeping the original term. This makes sense for user understanding, but it's worth considering whether to preserve brand names or product-specific terms in some cases.
Accuracy and quality
While Google Translate is widely known for its speed and broad language coverage, its translations can sometimes be less accurate than those produced by other services like DeepL. We can see that in our examples (Executive lounge translated to Polish).
OpenAI, similar to DeepL, produces high-quality translations that are close to human quality. The translations of all three services show some differences in terms of style and naturalness, but all are accurate and understandable.
Here is our rating of the translations in terms of accuracy and quality, based on the examples we analyzed:
The quality of translations can vary depending on the language pair and the complexity of the text. For more complex texts, it's recommended to use additional options provided by the translation service, like glossary, context, or key description, which can be used with auto-translation in both DeepL and OpenAI integrations.
Cost of translation
Pricing works differently across providers, and the billing units are not directly comparable. Below is an updated overview based on 2026 pricing.
Billing units: characters vs tokens
DeepL and Google Translate bill per character. OpenAI bills per token, split into input and output. As a rough estimate: 1,000 characters ≈ 250 input tokens + 250 output tokens for English. Output tokens cost 3-5x more than input tokens, and your system prompt (context, key descriptions, instructions) also counts as input tokens on every request.
DeepL pricing
DeepL offers two API plans for developers:
- DeepL API Developer: 1 million characters as a one-time credit for testing, no monthly fee
- DeepL API Growth: 1 million characters/month included for $32.50/month, then $27.50 per million extra characters, up to 50 million characters/month
DeepL's strength is translation quality for European language pairs. For non-European languages, the quality gap over competitors narrows, so the price premium may not be justified.
Google Translate pricing
Google Cloud Translation offers several tiers:
- 500,000 characters/month free (resets monthly)
- Basic NMT: $20 per million characters
- LLM Translation mode: $10 input + $10 output per million characters (no free tier; higher quality for nuanced content)
- Adaptive Translation: $25 + $25 per million characters (fine-tuned on your own data) Google supports 249 languages, making it the broadest-coverage option. The free tier is generous enough for development and staging environments.
Watch out for: billing counts HTML tags as characters. If you send rich-text content through the API, strip markup first or actual costs will run higher than estimated.
OpenAI pricing
OpenAI's most useful models for translation in 2026:
| Model | Input (per 1M tokens) | Output (per 1M tokens) |
|---|---|---|
| GPT-4o-mini | $0.15 | $0.60 |
| GPT-4o | $2.50 | $10.00 |
| Batch API (any model) | 50% off | 50% off |
GPT-4o-mini is the practical choice for most localization use cases: it competes with character-based MT on price while adding context awareness and instruction-following.
The Batch API (async, 24h turnaround) halves the cost for non-urgent translation runs, such as translating all missing keys overnight.
Cost comparison
Estimated cost to translate 500,000 and 1,000,000 characters into one language:
| DeepL API Growth | Google Translate NMT | GPT-4o-mini | |
|---|---|---|---|
| Billing unit | per character | per character | per token |
| 500,000 characters | included in plan | free tier | ~$0.40 |
| 1,000,000 characters | $32.50 | $20 | ~$0.75 |
| 2,000,000 characters | ~$60 | $40 | ~$1.50 |
GPT-4o-mini at these volumes is significantly cheaper than both traditional MT services while adding context-awareness. The trade-off is a more complex pricing model (input/output split, system prompt overhead) compared to the flat per-character rate of DeepL and Google.
Important notes:
- DeepL Growth plan includes 1M characters/month in the base fee, so the per-character rate only applies beyond that
- OpenAI cost estimates assume efficient batching with system prompts amortized across many strings per request
- Pricing changes regularly, verify current rates at DeepL API pricing, Google Cloud Translation pricing, and OpenAI API pricing
For a full breakdown including Gemini, Claude, DeepSeek, and how to estimate costs at scale, see our dedicated guide on how much AI translation costs.
Conclusion
All three platforms, DeepL, Google Translate, and OpenAI, produce accurate and understandable translations. The differences come down to naturalness, language coverage, and cost.
- DeepL produces the most natural-sounding output for European language pairs, at a price premium over Google.
- Google Translate covers the most languages (249) at a competitive price, with a generous free tier, and has improved quality meaningfully since the 2025 Gemini upgrade.
- OpenAI (GPT-4o-mini) is now competitive on cost with traditional MT services while adding context awareness, custom instructions, and consistent quality across all language pairs.
In all cases, machine translation should be treated as a strong starting point rather than a final output, particularly for customer-facing or brand-sensitive content. A human review pass for high-stakes copy remains good practice regardless of which provider you use.
