5-Star Reviews to Cancel a 1-Star: The Math in 3 Formulas

Originally published on ExtensionBooster.

How many 5-star reviews does it take to cancel a 1-star? If you want to stay at 4.8 stars, the answer is 19. That one number explains why a single angry review feels so heavy on a young extension or app, and this post gives you the three formulas (plus a tiny JS helper) to run the numbers for your own listing.

Your rating is just an average

Every store star rating is a mean of all the scores it counts. So a low score doesn't "go away"; it gets diluted by enough high scores to pull the average back to where you want it.

The higher your target, the less room each 5-star has to work with. At 4.9, a 5-star review sits only 0.1 above your target, while a 1-star sits 3.9 below it.

Formula 1: 5-stars needed to cancel one low review

To keep a target average T after one review of X stars:

fiveStarsNeeded = (T - X) / (5 - T)

For a 1-star review, that becomes (T - 1) / (5 - T). Rounded up:

Target average	5-star reviews to cancel one 1-star
4.0	3
4.5	7
4.7	13
4.8	19
4.9	39

Notice the curve: going from 4.8 to 4.9 roughly doubles the work.

Formula 2: 5-stars needed to raise your rating

If your current rating is R across N ratings and you want to reach T:

newFiveStars = N * (T - R) / (5 - T)

Real reviews are rarely all 5s. If new ratings average A, swap the 5 in the denominator for A.

Example: 100 ratings at 4.2, aiming for 4.5.

• If every new review is 5 stars: 100 × 0.3 ÷ 0.5 = 60 reviews
• If new reviews average 4.7: 100 × 0.3 ÷ 0.2 = about 150 reviews

And the hard limit: if new reviews average at or below your target, you can never reach it through more reviews. At that point the product needs fixing, not the review funnel.

Formula 3: how much one 1-star actually hurts

One new 1-star drops your average by:

drop = (R - 1) / (N + 1)

At a 4.5 rating:

Ratings you already have	Drop from one 1-star
10	about 0.32
20	about 0.17
250	about 0.01

A big rating count is a shock absorber. Early on, one bad review can visibly move your stars; later, it barely registers.

Here are all three as a small helper you can paste into a console or a dashboard:

// Round up, ignoring tiny floating-point noise (39.00000000000014 -> 39)
const roundUp = (x) => Math.ceil(x - 1e-9);

const cancelLowReview = (target, stars = 1) =>
  roundUp((target - stars) / (5 - target));

const reviewsToReach = (current, count, target, newAvg = 5) =>
  newAvg <= target ? Infinity : roundUp((count * (target - current)) / (newAvg - target));

const dropFromOneStar = (current, count) => (current - 1) / (count + 1);

cancelLowReview(4.8);             // 19
cancelLowReview(4.9);             // 39
reviewsToReach(4.2, 100, 4.5);    // 60
reviewsToReach(4.2, 100, 4.5, 4.7); // 150
dropFromOneStar(4.5, 10).toFixed(2); // "0.32"

Why the stores won't match your math exactly

The formulas assume a plain average. Each store bends that a little:

• Chrome Web Store: its August 2026 update says ratings will focus on more recent reviews. Google hasn't published the weighting, and ratings refresh daily.
• Google Play: ratings lean toward recent reviews and are calculated per country and device type, so do the math per market.
• Apple App Store: you can reset the summary rating with a new version. Written reviews stay, but the average restarts, so the small-count math applies again.
• Rounding: stores show one decimal and don't document how they round, so expect small differences.

Treat the formulas as a planning tool, not a prediction of the exact number on your listing.

What to do when a 1-star lands

1. Read it and find the actual cause.
2. Reply publicly within a day or two.
3. Fix the real issue if there is one.
4. Run the numbers against your rating count before panicking.
5. Ask for ratings after a user has a successful moment in your product.
6. Watch weekly trends instead of daily swings.

Honest reviews generally can't be deleted; you can report the ones that break policy. Buying or faking 5-star reviews is risky and can lead to removals or policy strikes.

Key takeaways

• Cancelling one 1-star takes (T - 1) / (5 - T) five-stars: 7 at 4.5, 19 at 4.8, 39 at 4.9.
• Raising a rating takes N * (T - R) / (A - T) new reviews, where A is the average of the new ones.
• If new reviews average at or below your target, more reviews won't get you there.
• One 1-star costs about 0.32 stars at 10 ratings but only about 0.01 at 250.
• Chrome, Play and the App Store weight or reset ratings differently, so use the math as a guide.

The original post goes deeper on each formula, with more tables, in the full guide to how many 5-star reviews cancel a 1-star rating. For more on growing reviews and ratings for browser extensions and apps, see ExtensionBooster's resources for extension developers.

What target rating do you aim for on your extension or app, and how did your listing react to its first 1-star review?