Free calculator
Star Rating Conversion Impact Calculator
Enter your traffic, conversion rate and order value, then model a conversion lift from better ratings or more reviews. The calculator turns the lift into orders and revenue per month and year.
Extra revenue per month
$1,404
$14,040 today vs $15,444 with the lift — about 22 more orders a month.
Extra revenue per year
$16,848
Published research agrees ratings move conversion; the exact lift depends on your category and starting point, so bracket it rather than trusting one number.
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What the research supports
Published research — Spiegel Research Center's work is the most cited — consistently finds that displaying ratings and reviews lifts purchase likelihood, with the biggest jump going from zero reviews to the first few, and diminishing returns near a perfect score (shoppers trust a 4.5–4.9 more than a flawless 5.0). The exact lift varies by category and price, so this calculator asks you to bracket it rather than pretending one number fits every store.
Which lever to pull
If products have few or no reviews, volume is the lever: post-delivery review requests at the right moment. If ratings are low, more requests just collect more complaints — fix the product or the expectation first (photos, size guides, honest copy), then let the rating recover.
Full walkthrough: Star rating vs review text: which one to trust.
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Frequently asked questions
How much do reviews increase conversion rate?
Published studies agree on the direction — showing ratings and reviews lifts conversion, with the largest effect on the first handful of reviews and on higher-priced, higher-risk purchases — but the size varies too much by category to quote one number honestly. Bracket it: model a conservative and an optimistic lift and treat the range as the answer.
Is a 5.0 star rating better than 4.7?
Counterintuitively, often not. Research (including Spiegel's) finds purchase likelihood peaking below a perfect score — a flawless 5.0 with few reviews reads as too good to be true, while a 4.5–4.9 with visible volume reads as real. Don't chase perfection; chase volume and recency.
How many reviews does a product need?
The first few matter most — going from zero to even a handful produces the largest trust jump, because an unreviewed product carries all the risk. After that, volume keeps helping but at a declining rate, and recency starts mattering more: a wall of two-year-old reviews raises its own questions.
Does star rating affect SEO?
Indirectly. Review content adds crawlable text and keeps pages fresh, and valid review markup makes stars eligible to show in search results — which lifts click-through even when rank is unchanged. The bigger effect is on-page: the traffic you already get converts better.