Ecommerce Metrics: The 12 Numbers That Matter, With Formulas

Twelve numbers tell you almost everything about an online store: how many visits turn into orders, what each order is worth, what it cost to get the customer, and whether they come back. Below is each one with its formula, the number for one example store, and the lever that moves it.

To keep the math honest, we carry one store through the whole post. Kestrel Run is the example running-shoe store we use across our site. Last quarter it had:

• 48,210 sessions
• 1,302 orders
• $208,320 in revenue
• $52,800 in ad spend
• 980 new customers

Every number below comes from those five.

1. Conversion rate

Formula: orders ÷ sessions × 100

Kestrel Run: 1,302 ÷ 48,210 = 2.70%

Conversion rate is the share of visits that end in an order. It's the first number to check after any change to a page, because it moves fastest. Measure it per landing page, not only for the whole store: a 2.70% average often hides one page at 3.4% and another at 1.2%.

What moves it: the page matching the ad that sent the visitor, load speed on phones, and how many steps sit between the first screen and checkout. Work out yours with the conversion rate calculator, and see how it compares in ecommerce conversion rates by industry.

2. Average order value (AOV)

Formula: revenue ÷ orders

Kestrel Run: $208,320 ÷ 1,302 = $160

AOV is what a typical order is worth. A page that sells bundles or a second pair can have a lower conversion rate and still make more money, which is why you read AOV next to conversion rate, never alone.

What moves it: bundles, free-shipping thresholds, and a second product on the page. Use the average order value calculator, and see nine tactics in how to increase average order value.

3. Revenue per session

Formula: revenue ÷ sessions, or conversion rate × AOV

Kestrel Run: $208,320 ÷ 48,210 = $4.32

Revenue per session is the one number that settles arguments between conversion rate and AOV. If a new page converts less but sells bigger orders, revenue per session tells you which version actually earns more per visit. It's also the ceiling on what you can pay for a click.

What moves it: anything that moves conversion rate or AOV. If you only watch one number per landing page, watch this one.

4. Add-to-cart rate

Formula: sessions with an add to cart ÷ sessions × 100

Kestrel Run: 4,820 ÷ 48,210 = 10.0%

Add-to-cart rate tells you whether the page itself is persuading. If it's low, the problem is above the buy button: the offer, the photos, the price or the proof. If it's healthy and conversion is still low, the problem is after the cart.

What moves it: a clear offer on the first screen, reviews near the button, and size or variant pickers that don't fight the shopper. Try the add-to-cart rate calculator.

5. Cart abandonment rate

Formula: 1 − (orders ÷ carts created), as a percentage

Kestrel Run: 1 − (1,302 ÷ 4,820) = 73.0%

Most carts never become orders, and 70% or so is normal. The number is still worth watching, because a jump usually means something broke: a shipping cost that appears late, a discount code that fails, a payment option that disappeared.

What moves it: showing shipping costs early, fewer checkout fields, express payment buttons, and an abandoned-cart email. Use the cart abandonment rate calculator.

6. Customer acquisition cost (CAC)

Formula: ad and marketing spend ÷ new customers

Kestrel Run: $52,800 ÷ 980 = $53.88

CAC is what you paid, on average, for each new customer. Count only new customers in the denominator; returning buyers would make it look cheaper than it is.

What moves it: better-converting landing pages (the same spend buys more customers), tighter targeting, and fewer clicks sent to a homepage that wasn't built for the ad.

7. ROAS and MER

ROAS formula: revenue credited to ads ÷ ad spend

MER formula: total revenue ÷ total ad spend

Kestrel Run: the ad platforms credit $142,560 to their ads, so ROAS = $142,560 ÷ $52,800 = 2.70. MER = $208,320 ÷ $52,800 = 3.95.

Return on ad spend (ROAS) comes from each ad platform and tells you which channel or campaign to cut. Marketing efficiency ratio (MER), sometimes called blended ROAS, ignores attribution entirely and asks whether the whole budget is paying off. Platforms tend to over-credit themselves, so read both: ROAS to compare campaigns, MER to decide the budget.

What moves it: the landing page as much as the ad. The same click is worth more on a page that converts at 3.4% than on one at 1.2%.

8. Customer lifetime value (LTV)

Formula: AOV × purchases per year × years as a customer. Multiply by gross margin for profit LTV.

Kestrel Run: $160 × 1.6 orders a year × 2 years = $512 in revenue. At a 55% gross margin, profit LTV = $281.60.

LTV is what a customer is worth over the whole relationship. Use the margin version when you compare it with CAC, because you pay for ads out of profit, not revenue.

What moves it: a reason to come back (refills, new colors, a members' price), post-purchase email, and subscriptions where the product fits.

9. LTV:CAC ratio

Formula: profit LTV ÷ CAC

Kestrel Run: $281.60 ÷ $53.88 = 5.2:1

This ratio tells you how much room you have to spend on growth. Around 3:1 is the usual target; much lower and each customer barely pays back, much higher and you may be underspending. Work through yours with the LTV:CAC ratio calculator, and read what is a good LTV to CAC ratio for the benchmarks.

10. Repeat purchase rate

Formula: customers with two or more orders ever ÷ all customers × 100

Kestrel Run: of 1,180 customers who ordered last quarter, 290 have ordered at least twice, so 24.6%.

Repeat purchase rate is the early signal for LTV, and it shows up months before LTV settles. A falling rate usually means the first order disappointed, or nothing gave the customer a reason to return.

What moves it: the product itself, the unboxing, and a follow-up offer timed to when the first pair wears out.

11. Units per transaction (UPT)

Formula: units sold ÷ orders

Kestrel Run: 2,083 ÷ 1,302 = 1.60

UPT tells you whether shoppers buy one thing or a set. It's the lever behind AOV that you control most directly with the page: bundles, "complete the kit" sections, and multi-pack pricing. Use the units per transaction calculator.

12. Bounce rate and the funnel

Bounce rate formula: single-page sessions ÷ sessions × 100

Kestrel Run: 20,250 ÷ 48,210 = 42.0%

Bounce rate on its own is a weak number, since a shopper who buys from the first page they land on still counts as engaged. It earns its place as the top of the funnel, read per landing page:

• Page view: 48,210 sessions
• Add to cart: 4,820 (10.0%)
• Checkout started: 2,410 (5.0%)
• Purchase: 1,302 (2.70%)

The step with the biggest drop is the one to fix first. Here, half the visitors who start checkout finish it, which points at shipping costs or payment options before it points at the page. For more on reading a landing page this way, see landing page analytics metrics that matter.

Which of these we track for you

On every site you publish with us, Insights tracks sessions, page views, add-to-carts, checkouts and purchases from the moment you publish, with nothing to install. That covers conversion rate, AOV, revenue per session, add-to-cart rate and the funnel for each landing page, with revenue counted two ways: session revenue and attributed revenue. It's free on every plan.

ROAS, MER and CAC need ad spend, so we read them from Meta, Google Ads or Triple Whale once you connect them. LTV and repeat purchase rate need your full order history, so they come from your store platform. You can ask for any of the twelve in plain English, or have the report land in your inbox every Monday.

See what Insights measures