CIDEr Score Calculator
Calculate the CIDEr score used to evaluate image captioning model outputs.
About CIDEr Score Calculator
CIDEr (Consensus-based Image Description Evaluation) measures image captioning quality by computing TF-IDF weighted n-gram vectors for candidate and reference captions, then calculating their cosine similarity. It rewards captions that use words common in references but rare across the corpus, capturing consensus among annotators.
Formula
CIDEr
CIDEr_n = (1/M) * sum(cos_sim(tfidf_candidate, tfidf_ref_j)) * 10
- M
- Number of reference captions
- cos_sim
- Cosine similarity of TF-IDF vectors
Worked example
With the default values below, CIDEr Score Calculator returns CIDEr Score of 7.2000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Avg Cosine Similarity (TF-IDF)accepts 0–1
- 0.72
- Number of Referencesaccepts 1–100
- 5
- Max N-gram Orderaccepts 1–8
- 4
Results
- CIDEr Score
- 7.2000
- Scaled Similarity
- 7.2000
Step by step
- 1Average TF-IDF cosine similarity= 0.7200
- 2CIDEr score (scaled ×10)= 7.2000
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why does CIDEr use TF-IDF weighting?
TF-IDF downweights common words (like 'the', 'a') and upweights informative words (like 'surfboard', 'sunset'), so CIDEr rewards captions that capture the distinctive content of an image rather than just generic descriptions.
Why is CIDEr multiplied by 10?
The scaling factor of 10 is a convention to make scores more readable — raw cosine similarities are typically between 0 and 1, so multiplying by 10 gives a more intuitive range.