AI Reranker Cost Calculator — Cohere vs Voyage vs Jina

A reranker sits between retrieval and generation in a RAG pipeline: your vector search returns a rough candidate set, and the reranker reorders those candidates by true relevance before the top few are handed to the language model. It is a cost stage teams often forget to price. The two billing models the major hosted rerankers use are computed independently below, each from the provider's published rate.

A. Search-unit billing (Cohere)

Cohere bills in search units. One search unit is a single query reranked against up to 100 documents; a query with more than 100 documents consumes ceil(documents ÷ 100) units. Token length does not enter the count for passages under about 500 tokens.

• search_units_per_query = ceil(docs_per_query ÷ 100)
• total_search_units = queries_per_month × search_units_per_query
• cost_usd = total_search_units × (price_per_1000_su ÷ 1000)

B. Token billing (Voyage, Jina)

Voyage and Jina bill per 1,000,000 tokens, counting both the query tokens and every candidate document's tokens on each query. Document tokens dominate the total, so shrinking your retrieval top-k directly cuts the bill.

• tokens_per_query = query_tokens + (docs_per_query × avg_doc_tokens)
• total_tokens = queries_per_month × tokens_per_query
• cost_usd = (total_tokens ÷ 1,000,000) × price_per_1M_tokens

For both models, cost per 1,000 queries is cost_usd ÷ queries_per_month × 1000. Every monthly figure is cross-checked against its own cost-per-1,000-queries value, so the two numbers can never drift apart — the same two-methods-agree approach this site uses for its tax calculator. The rates baked in were verified against the live Cohere, Voyage AI and Jina AI pricing pages on 2026-07-08: Cohere Rerank 3.5 at $2.00 per 1,000 search units, Voyage rerank-2 at $0.05 per 1M tokens, Voyage rerank-2-lite and Jina Reranker v2 at $0.02 per 1M tokens.

• Cohere — Rerank pricing (search-unit rate)
• Cohere — how pricing works & the search-unit definition
• Voyage AI — reranker pricing (per 1M tokens)
• Jina AI — Reranker API pricing

Provider rates were last cross-checked against these pages on 2026-07-08. Prices are headline pay-as-you-go rates and exclude free tiers and committed-use discounts. Reranker pricing is reviewed quarterly.