How to calculate ecommerce review ROI with an example

What to take away

Build the calculation before you buy

Use this formula: ROI = (incremental gross profit attributable to reviews − total review costs) ÷ total review costs × 100. Keep the periods consistent, include repeat-purchase gross profit only when it can be attributed to review engagement, and do not count the same order twice.

Start with the decision, not the tool

You are choosing between three spending routes: review software, such as Trustpilot, Feefo or Reviews.io; an agency; or in-house collection. Each has a different cost shape, so the return differs even when review volume is identical. Write down the payback period you will accept before you see any quote.

Use the same baseline for every option: one conversion rate, one average order value and one review volume assumption. For a full breakdown of these routes, see our commerce reviews costs and budget guide for England.

Set the threshold in writing before quotes arrive: payback within two quarters and positive contribution once fixed costs are paid. A cheap tool that collects unusable reviews fails that test as fast as an expensive one.

Choose the three inputs you can defend

Start with review volume, estimated from your order volume and historical collection rate rather than a target. Conversion lift on product pages that carry reviews, measured against pages without them, gives you the second input. The third is repeat purchase rate among customers who engage with reviews.

The Office for National Statistics publishes digital economy statistics covering e-commerce and online retail trends, which helps you check whether your growth assumption is reasonable for the sector. If your assumed lift sits far above the wider market, question it.

Cost lines that decide the payback

Include fixed and variable fees in total review costs. Add any per-review or per-order charge for the period to software, moderation, incentives, sampling, email fees and staff time; leaving costs out overstates ROI.

Fixed fees and variable fees behave differently

Most software contracts charge a monthly platform fee plus a per-review or per-order charge. The monthly fee is fixed and hurts most in quiet months. The variable fee rises with sales, so it dilutes margin on every incremental order.

Ask what happens in a month when orders halve. A per-order contract shrinks with demand; a flat fee does not. That asymmetry often decides which contract pays back, not the headline rate.

Pricing structures vary widely, and the differences matter more than the headline rate. Our guide to commerce reviews pricing models in England explains how per-review, per-order and flat-fee contracts change your break-even point.

Compliance and moderation are real costs

The Digital Markets, Competition and Consumers Act 2024 gives enforcers powers over fake and misleading reviews. The Competition and Markets Authority (CMA) is the UK enforcement authority for consumer protection, including these rules. The full text of the Act sets out the duties that apply to traders. Budget for moderation time or a moderation service, because a tool that admits unverified reviews carries real risk.

Worked example and the quarterly check

The example uses the conversion-led gross profit in the stated figures. Let R represent incremental gross profit from repeat purchases at the measured repeat-purchase rate, and V represent actual monthly per-review or per-order charges. Neither amount is provided, so the example can show a provisional ROI using the known costs, but a fully loaded ROI requires adding R to returns and V to costs.

A worked example with labelled figures

For example, a homeware team spends £600 a month on software and £200 on moderation, so £800 a month, or £9,600 a year. They collect 400 reviews a month. Assume a 2% conversion lift on 20,000 monthly product page sessions, an average order value of £45 and a 35% gross margin. The figures do not state a variable fee or repeat-purchase rate, so neither a variable charge nor repeat-order profit is included in the numerical calculation.

That lift produces 400 extra orders a month, worth £18,000 in revenue and £6,300 in gross profit. Subtract the £800 monthly cost and contribution is £5,500 a month, roughly £66,000 a year, so payback arrives inside the first month. At a 0.5% lift, contribution falls to about £775 a month.

Recheck the numbers each quarter

Review volume, platform fees and conversion lift all move, so rebuild the calculation quarterly with actual figures. Keep the previous version so you can see which input changed. Compare like quarters rather than consecutive months, because November volumes flatter almost any contract.

When planning paid support for review campaigns, the guidance on running successful Google Ads campaigns covers setting budgets and measuring incremental return, not last-click revenue.

Common questions

What counts as a good return on commerce reviews?

Aim for payback inside two quarters and positive contribution after every fixed cost. If the sum only works when you exclude moderation, it does not work.

Should I include review collection costs in the return?

Yes. Incentives, sampling, email platform fees and staff time all belong in the calculation. Leaving them out flatters the result.

How does UK consumer law affect the numbers?

The Digital Markets, Competition and Consumers Act 2024 makes misleading review practices a consumer protection matter, enforced by the Competition and Markets Authority (CMA). That adds moderation and record-keeping cost. Compliance therefore sits inside the return calculation.

How often should I revisit the calculation?

Quarterly is usually enough, or sooner if you change provider, renegotiate a contract or see conversion lift move by more than a percentage point.