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Overview

NFT rarity measures how unique an NFT is within its collection, based on how common or uncommon its attributes are compared to other NFTs in the same collection. In most NFT collections, traits such as background, color, accessories, or attributes appear at different frequencies. NFTs with less common trait combinations are considered rarer and are often perceived as more valuable by collectors, marketplaces, and analytics platforms. Moralis provides deterministic, collection-wide rarity scores and rankings, calculated directly from indexed NFT metadata. Related pages:

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How rarity is calculated

Moralis computes rarity per collection, not globally. The rarity calculation process consists of two layers:

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1. Trait-level analysis

For every trait across the collection, we compute:
  • count
    Number of NFTs that contain this trait
  • percentage
    Percentage of the collection that contains this trait
  • rarity_label
    Human-readable label based on trait frequency
    (e.g. “Top 1% trait”, “Top 10% trait”)
This makes rarity explainable, not just numeric.

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2. NFT-level rarity scoring

For each NFT, we compute:
  • rarity_score
    Numerical score derived from the combined rarity of all its traits
  • rarity_rank
    Rank of the NFT within the collection (1 = rarest)
  • rarity_percentage
    Relative rarity compared to the entire collection
  • rarity_label
    Human-readable summary (e.g. “Top 1% rarity”)
These fields are returned directly in supported NFT endpoints.

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Supported collections

Rarity calculations are supported for:
  • ERC-721 collections
  • ERC-1155 collections
With the following constraints:
  • Maximum collection size: 50,000 NFTs
  • All NFTs must be discoverable and indexed
  • Metadata and traits must be available for the full collection
If these conditions are not met, rarity will not be calculated.

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Supported chains

NFT rarity is supported on all EVM chains where Moralis NFT metadata is available, including:
  • Ethereum
  • Polygon
  • Base
  • Arbitrum
  • Optimism
  • BNB Chain
  • Other supported EVM chains
Rarity logic is chain-agnostic and applied consistently.

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Trait syncing & rarity processing

Rarity is computed on demand, per collection.

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Initial sync flow

  1. A collection is queried using getNFTTraitsByCollection
  2. The collection is added to a processing queue
  3. Traits are synced for all NFTs
  4. Rarity scores and rankings are calculated
While processing is in progress, trait endpoints return: 
202 – Contract is being resynced at the moment. Please try again later.

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Processing times

Typical processing times:
  • Small collections: 5–15 seconds
  • Medium collections: 15–60 seconds
  • Large collections (20,000+ NFTs): may take longer
If processing exceeds 5 minutes, contact support. Once queued, a collection cannot be reprocessed again for 30 minutes.

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Refreshing rarity scores

Rarity scores can be refreshed after:
  • NFT reveals
  • New mints
  • Metadata or trait updates
Refreshing rarity is triggered by re-syncing traits, which automatically recalculates all rarity data. See:

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Why rarity matters

NFT rarity enables:
  • Collection ranking & discovery
  • Trait-based filtering
  • Floor price and valuation analysis
  • Wallet and portfolio insights
  • Marketplace and analytics UIs
Without indexing internal trait distributions, rarity cannot be computed accurately - which is why many platforms approximate or omit this entirely.

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Best practices

  • Don’t assume rarity exists until processing completes
  • Handle 202 responses gracefully
  • Cache rarity results when possible
  • Re-sync after major collection events (e.g. reveals)

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Summary

Moralis NFT Rarity provides:
  • Deterministic rarity scores
  • Trait-level transparency
  • Collection-wide rankings
  • Multichain support (EVM)
  • Refreshable, on-demand computation
This allows you to build analytics, discovery, and marketplace experiences without maintaining your own rarity infrastructure.