Head-to-head comparison
Mercury 2 (Inception Labs) and Mercury 2.5 Preview (Inception Labs) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.
Snapshot as of 3 September 2026
As of 3 September 2026, Mercury 2 holds the stronger ModelCap Index position (#85 vs #94); Mercury 2.5 Preview is 5× cheaper per output token ($0.15/1M vs $0.75/1M); and Mercury 2.5 Preview offers the longer context window (260K vs 128K tokens).
Evidence: 3 public benchmark observations across 3 boards · start rank inherited from the measured predecessor in its own product family, less a fixed succession penalty, until independent measurements replace it. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.
Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.
Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.
Mercury 2 ranks higher on the ModelCap Index as of 3 September 2026: #85 against #94. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it.
Mercury 2.5 Preview is cheaper on output tokens: $0.15/1M against $0.75/1M. Input tokens are $0.25/1M for Mercury 2 and $0.04/1M for Mercury 2.5 Preview. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens.
Mercury 2.5 Preview has the larger context window: 260K tokens against 128K.
The two models do not share a coding benchmark board on ModelCap yet, so no head-to-head coding score is published; the ModelCap Index position is the closest overall signal.
Mercury 2: API only. Mercury 2.5 Preview: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.
ModelCap currently lists 1 API provider for Mercury 2 and 1 for Mercury 2.5 Preview, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.
Every figure comes from the sealed ModelCap dataset published 3 September 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.