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Rating models

Time-decay rating calculator

Estimate a rating that gives recent reviews more weight using an adjustable half-life.

Model estimate, not a platform prediction. Results may differ from real service ratings. Platforms can use unpublished weights, moderation, eligibility rules and rounding. This calculator applies only the formula below.

Your inputs

Time-based scenarios age the existing reviews by the evaluation offset. New-review age is measured on that evaluation day. Reviews outside the window contribute nothing.

Reset example
Time-decay rating · model result
4.251 / 5

100 reviews in the included groups. Group averages can make the result approximate.

Results are rounded to three decimal places.

How it works

weight = 2^(−age ÷ half-life); rating = Σ(rating × count × weight) ÷ Σ(count × weight)

This model uses exponential decay. After one half-life a review has half its original weight. Google Play gives recent ratings more weight, but does not publish this formula. A group assumes all its reviews have the entered age.

Google Play: ratings and reviews

Results update as you type. Calculations run in your browser; submitting with JavaScript disabled sends the numbers to the server to calculate the result.

Reach a target

Minimum additional 5-star reviews. Both panels use the assumptions above. Existing reviews are not edited or removed except by this method’s time window or trimming rule.

25

additional reviews needed

Simulate new ratings

4.379 / 5

110 reviews in the included groups. Group averages can make the result approximate.

Other rating methods