Can you translate contracts with AI? Do press releases still need a human? This post gives you a practical decision framework across four dimensions: quality, speed, cost, and risk.
The three buckets that actually matter
Every business document falls into one of three categories, and that bucket determines whether AI alone, a human, or a hybrid is the right answer.
- A. Internal or reference docs — inbound email, research, internal memos. "Good enough to get the meaning" is enough. AI alone works.
- B. Outbound business docs — proposals, manuals, sales decks, support content. Brand and consistency matter. Use AI translation with a human review step.
- C. Legal and regulated docs — contracts, terms of service, shareholder notices, patents, pharma filings. Errors carry real legal risk. Humans required — but AI can still draft, cutting time in half.
The four dimensions, compared
1. Quality: depends on language pair and document type
For English ↔ Japanese, frontier models (Claude 3.5 Sonnet, GPT-5) now produce output on par with experienced translators for typical business writing. They struggle in three places:
- Japanese politeness levels — keigo depends on the reader and situation. Without context, AI defaults to generic translations that miss the nuance.
- Industry terminology — pharma, finance, legal, each have established terms. Without a glossary, AI picks plausible but non-standard wording.
- Dropped subjects — Japanese routinely omits the subject. AI sometimes infers the wrong one.
2. Speed: AI wins by orders of magnitude
For a 20-page Word document:
- Professional translator: 2–3 business days
- Internal bilingual staff: 5–10 business days (fit around their real job)
- AI (BizHonyaku): 2–3 minutes
- AI + human review: half a day to one business day
3. Cost: 100× difference
Japanese market rates for human translation run 8–25 JPY per character. A 10,000-character document costs 80,000–250,000 JPY. The same document through AI costs a few hundred to a few thousand yen — more than 100× cheaper.
4. Risk: varies by domain
Think in terms of the cost of a mistranslation.
- High (human mandatory): contracts, shareholder materials, patents, pharma inserts, employment agreements, software licenses. Mistranslation = litigation.
- Medium (AI + review): customer manuals, sales decks, support replies, brand copy. Mistranslation = lost trust.
- Low (AI alone is fine): internal email, research notes, reading comprehension, social posts. Mistranslation = quick fix.
A decision flowchart
- Does this document leave the company? If no → AI is enough.
- Is it legally binding? If yes → human required (AI can draft).
- Does it affect brand? If yes → AI with human review.
- Heavy specialized vocabulary? If yes → build the glossary first.
- More than 10 translations per month? → Move to AI as baseline and budget review time.
The hybrid workflow, in practice
For most organizations, the right answer is AI drafts, human reviews. Three concrete wins:
- 50–70% less work: editing a draft beats translating from scratch.
- Consistency: feed your glossary to the AI and the output stops drifting between translators.
- More language pairs: you no longer need an in-house Chinese or Korean translator to produce usable drafts.
The short version
Stop thinking of AI as a replacement for human translation. It is the first step of the process. Classify your documents by risk and purpose, make that a written policy, and both cost and quality scale.
BizHonyaku bundles the AI draft and the human review loop into one dashboard, with glossary, templates, and side-by-side diff built in — so the hybrid workflow above runs out of the box.