Review Rating Calculator
Compute your exact star-rating average from 5- to 1-star counts and how many new genuine 5- or 4-star reviews it would take to reach a target average.
Interactive calculator · Method REVIEW-RATING-1.0 · Last reviewed: 2026-11-04
Calculate your scenario
Average = (5×n5 + 4×n4 + 3×n3 + 2×n2 + 1×n1) ÷ total reviews.
Your inputs
Default worked example. Edit the inputs to calculate your scenario.
Default worked example
Average = 775 total stars ÷ 180 reviews = 4.3056; with 20 new 5-star reviews: (775 + 100) ÷ 200 = 4.375 stars.
How to use the calculator
Enter how many reviews you have at each star level (most platforms show the breakdown), the exact average you aim for, the rating of the new reviews to model, and a number of new reviews to preview.
What the result means
With 180 reviews totaling 775 stars the exact average is 4.3056 (shown as 4.3). Reaching an exact 4.5 takes 70 more five-star reviews, since (775 + 350) ÷ 250 = 4.5.
Formula and units
Average = (5×n5 + 4×n4 + 3×n3 + 2×n2 + 1×n1) ÷ total reviews. The number of new r-star reviews k needed for target t is the smallest whole k with (stars + k×r) ÷ (reviews + k) ≥ t, i.e. k = ⌈(t × reviews − stars) ÷ (r − t)⌉. If r is not above t, no number of r-star reviews can reach it.
Worked examples
180 reviews averaging 4.31, target 4.5: 5-star reviews: 120 reviews; 4-star reviews: 30 reviews; 3-star reviews: 10 reviews; 2-star reviews: 5 reviews; 1-star reviews: 15 reviews; Target exact average: 4.5 stars; New reviews to preview: 20 reviews; Rating of hypothetical new reviews: 5.
Example result: Current average: 4.3056 stars; Rounded to one decimal: 4.3; Total reviews: 180; New reviews needed for target: 70 five-star reviews (average then 4.5); Average after planned reviews: 4.375 stars.
50 reviews averaging 4.8, target 4.9: 5-star reviews: 40 reviews; 4-star reviews: 10 reviews; 3-star reviews: 0 reviews; 2-star reviews: 0 reviews; 1-star reviews: 0 reviews; Target exact average: 4.9 stars; New reviews to preview: 20 reviews; Rating of hypothetical new reviews: 5.
Example result: Current average: 4.8 stars; Rounded to one decimal: 4.8; Total reviews: 50; New reviews needed for target: 50 five-star reviews (average then 4.9); Average after planned reviews: 4.8571 stars.
Limitations and common mistakes
Uses the exact counts you enter; a rounded public average cannot be turned back into counts. Platforms may weight, filter or round ratings differently, so the target is an exact average, not a displayed one. Plan only around genuine reviews from real customers; buying, gating or fabricating reviews breaks platform rules and consumer-protection law in many places.
Targeting the displayed rating: a page that rounds to one decimal can show 4.5 at an exact 4.45, so enter the exact average you need rather than the rounded label.
Sources and assumptions
Method REVIEW-RATING-1.0; last formula review 2026-11-04. Sources and their supported claims. Calculation methodology.