The CRO ROI formula
ROI = (gain − cost) ÷ cost × 100. The gain is the extra revenue over a fixed period. This calculator uses 12 months. The cost is everything you pay for the change: the audit, the developer or designer time, and any app you add.
Payback period = cost ÷ extra revenue per month. For a small store, payback is often the more useful number. A 300% return means little if the money comes back in month 11 and you needed it in month 2.
Worked example
A store has 8,000 visitors a month, converts 1.8%, and has an average order value of $55. Monthly revenue: 8,000 × 1.8% × $55 = $7,920. With a 10% relative uplift, the rate goes to 1.98% and revenue goes up by $792 a month, or $9,504 over 12 months.
| Option | Cost | 12-month ROI | Payback |
|---|---|---|---|
| Agency audit (agency audits usually cost $2,000 to $12,000; $3,000 used here) | $3,000 | 217% | 3.8 months |
| Our full audit ($14.95) plus $500 of developer time for the fixes | $514.95 | 1,746% | 0.65 months (about 20 days) |
The agency figure is a market range, not a quote, and an agency often does more than the audit. The example also assumes both routes find fixes worth the same 10%. Your real numbers depend on what the store gets wrong. For the full comparison, read CRO agency vs AI audit tool.
The relative vs absolute uplift trap
This is the most common mistake in CRO business cases. A "10% uplift" on a 1.8% rate means 1.98% (relative). It does not mean 11.8% (absolute, in percentage points). The absolute reading makes the gain more than 50 times too large.
When an agency or a case study says "conversion rate up 25%", ask which one they mean. If they say "up 1 point", that is absolute: from 2% to 3% is a 50% relative lift.
Revenue is not profit
The calculator shows revenue. To get profit, multiply by your gross margin. At a 40% margin, the $9,504 in the example is about $3,800 of profit. Use the profit figure when the fix is expensive, because a return that looks good on revenue can be thin on profit.
Pick a careful uplift
- 5% to 10% for a store that already works and gets small improvements.
- Higher only when the store has clear, broken things: an add-to-cart button below the fold on mobile, a shipping cost that appears only at checkout, a slow product page.
- Never use a case-study number as your input. Those are the best results someone chose to publish.
If you do not know what is broken, find out first. The uplift you put in this calculator is only as good as your list of problems.
Method: 12-month revenue ROI with a relative uplift at the same traffic and average order value; no margin, discounting or seasonality applied.