What does the Review Velocity Calculator do?

It answers three questions on one timeline: how many reviews you'll have over the next 36 months under different sales trends, how many 5-star (or 1-star) reviews move your displayed rating to any 0.1★ milestone, and when — or at what pace — you'd catch a competitor's review count. It's free, runs entirely in your browser, and needs no account.

How many reviews do Amazon sellers typically get per sale?

Most listings convert 1–3% of orders into reviews — roughly 1 review per 33–100 orders. Amazon's Request-a-Review button, well-timed inserts, and the Vine program push you toward the top of that range. The calculator defaults to 3% and lets you test 0.5–10%.

How many 5-star reviews do I need to raise my rating?

Amazon displays your rating rounded to 0.1★, so reaching a displayed 4.5★ means pushing your true average to at least 4.45. From 100 reviews at 4.0★ that takes 82 consecutive five-star reviews — the calculator solves this for any starting point and any 0.1★ target, in both directions.

Why can't I reach my target rating?

Your average converges toward the average star of your incoming reviews — that's the ceiling. If incoming reviews average 4.4★, your rating approaches 4.4★ and never displays 4.5★, no matter how many reviews arrive. When that happens the calculator names the incoming average you'd need instead of pretending volume will fix it.

How do I estimate a competitor's review velocity?

Divide their review count by the listing's age in months — a listing with 1,200 reviews that's 40 months old averages +30/mo. That's a lifetime average: established listings often gain faster today than their average suggests, so treat it as a floor and test a faster pace too.

How accurate is the forecast?

It models the arithmetic mean of your reviews, while Amazon's displayed rating is a weighted model (recency and verified purchases weigh more), and it assumes reviews land the same month as their orders. Direction and rough magnitude are reliable; the exact month is not a guarantee. Treat it as a planning tool, not a promise.

Review Velocity Calculator

Review growth, rating forecast, and competitor catch-up

287 reviews · 4.5★ · +9/mo · +3%/mo

Your numbers

Product

Reviews today

Displayed rating

Sales

Units sold / month

Review rate %

typical: 1–3% of buyers leave a review

Sales trend

New reviews

5★ share %

1★ share %

2–4★ fill the rest (24%) · 4.38★ incoming average

Competitor

Their reviews

Their pace / month

estimate: their reviews ÷ listing age in months

+9 new reviews a month

compounding at +3%/mo

Review goalmonth 19

Month 14 if sales take off, month 24 if they stay flat.

Rating goalnever

At a 4.38★ incoming average you lose your 4.5★ display around month 18. Cut your 1★ share to 3% and you'd settle at 4.5★ instead.

Catch rival+102/mo

That's about 3,400 units/mo at your 3% review rate. At your current pace, parity waits until ≈ month 88.

Show competitor (1,374 reviews, +30/mo)

What to do next

Cut your 1★ share 6% → 3% (fix the top complaint): you'd settle at 4.5★ instead of 4.4★.
Lift your review rate 3% → 4% (Request-a-Review, inserts): 500 reviews by month 15 instead of 19.
Catching them in 1 year is a sales target: +102 reviews/mo ≈ 3,400 units/mo.

How review velocity works — and what really moves your rating

Review velocity
Your velocity is simply monthly orders × review rate: 300 orders at a 3% review rate adds about 9 reviews a month. Because orders usually grow, velocity compounds — the pace you have today understates where you'll be in a year.
The review rate
Between 1% and 3% of Amazon buyers leave a review; great inserts, the Request-a-Review button, and Vine push toward the top of that range. Doubling the rate doubles your velocity without selling one extra unit — it's the cheapest lever you have.
The 5-star math
Your displayed rating is a weighted average, so every milestone has a price in reviews: at 100 reviews and 4.0★, it takes 82 five-star reviews to display 4.5★. The price scales with your base — at 1,000 reviews it's 819. Rating inertia grows as you grow.
The 1-star damage
The math is brutally asymmetric: the climb scales with your entire review base, the fall doesn't. The same 100-review listing that needs 82 five-stars to climb to 4.5★ loses that display after just 2 one-star reviews. Your cushion — how many bad reviews you can absorb — is a number worth knowing before a bad batch ships.
Your rating's ceiling
Your rating converges to the average star of your incoming reviews. If new reviews average 4.4★, no amount of volume ever displays 4.5★ — the target is mathematically unreachable until the product itself improves. Fix the mix before scaling the velocity.
Catching a competitor
Catch-up is gap ÷ closing speed: 1,000 reviews of gap closes in 20 months at +50/mo net. If your velocity is below theirs, the gap only widens — the calculator flips to the velocity you'd need, and since velocity is orders × rate, that's really a sales-volume target.