How to calculate your VAMP ratio, with a Shopify calculator

A merchant sent me a screenshot last month. Their Shopify chargeback rate read 0.38%. Their acquirer had just written to them about VAMP exposure.

Neither number was wrong. They measure different things, and only one of them is the number Visa acts on. Here is the formula, the current thresholds, and a calculator that runs both once you have your own four numbers.

What is the VAMP ratio, and how do you calculate it?

Visa's VAMP fact sheet states it in a single line: the VAMP ratio is the count of Fraud (TC40) plus Disputes (TC15), divided by the count of Settled Transactions (TC05).

Four things in that line do most of the work.

It is a count, not a dollar figure. A $12 dispute and a $1,200 dispute are one event each. Merchants who assume the ratio is value-weighted underestimate their exposure, because cheap orders generate disputes at a rate that has nothing to do with their share of revenue.

The numerator is two feeds added together. TC40 is the fraud report an issuer files. TC15 is the dispute record. Visa's fact sheet describes the numerator as the sum of both counts and publishes no de-duplication rule, so ask your acquirer how a fraud-coded dispute lands in your report rather than assuming it counts once.

The denominator is card-not-present only. Visa scopes the metric to card-not-present VisaNet transactions, domestic and cross-border. Any in-person volume you run, including pop-ups and trade shows, does not dilute the ratio.

The window is one calendar month. Visa evaluates monthly. A quarterly average hides the month that actually triggers identification.

Running the numbers

Take a store with 42,000 settled Visa card-not-present transactions in June, 120 TC40 fraud reports, and 340 TC15 disputes.

Numerator: 120 plus 340 is 460. Divide by 42,000 and you get 0.01095, which is 109 basis points, or 1.09%. That is under the 150 basis point threshold most regions use in 2026, with room for roughly 170 more events at the same volume.

That is the arithmetic done by hand, once, so you can see the mechanics. Run your own four numbers below.

What the four inputs mean, and where to find them

Fraud reports (TC40). Issuer-reported fraud on your Visa transactions. Most merchants cannot pull this themselves, because a TC40 can exist without a chargeback ever reaching your admin. Ask your acquirer for the monthly count. If you cannot get it, run the calculator with disputes only and treat the result as a floor rather than an estimate.

Disputes (TC15). Your Visa dispute count for the month, fraud and non-fraud combined. Visa merged the two into one program, so there is no reason to track them separately here.

Settled card-not-present transactions (TC05). The next section covers this one in detail, since it is where most merchants get the number wrong.

Region. Sets both the threshold and the count floor. Most Shopify merchants selling into the US, Canada, Europe, Asia Pacific, or Latin America and the Caribbean use the same figures. CEMEA sits on a different ratio and a different floor.

Why your Shopify dashboard shows a different number

Shopify shows you a chargeback rate. It is a useful operational number and it is not the VAMP ratio.

The numerator differs. Shopify reports what arrived in your Shopify Payments account. Visa counts TC40 fraud reports that may never have become a chargeback you saw, plus TC15 records across your whole Visa acceptance.

The denominator differs more, and it is the bigger gap. A platform rate is computed over your orders. VAMP's denominator is settled Visa card-not-present transactions only. Strip out Mastercard, Amex, PayPal, and any card-present volume, and the denominator often shrinks by a third or more. Hold the same dispute count against a denominator a third smaller and the ratio comes out roughly 50% higher.

This is the most common reason a merchant is blindsided by an acquirer letter. They were watching an honest number that nobody was enforcing.

The 2026 thresholds, and the count floor most calculators skip

As of April 1, 2026, the excessive-merchant threshold is 150 basis points in the US, Canada, Europe, Asia Pacific, and Latin America and the Caribbean. CEMEA sits at 220 basis points.

The ratio alone does not identify you. Visa pairs it with a monthly count floor: 1,500 fraud-plus-dispute events in every region except CEMEA, where the floor is 150 events plus a USD 75,000 minimum. A Shopify brand running 300 basis points on 200 events a month is over the ratio and under the floor, which is a materially different problem than a brand over both.

Verify current thresholds against Visa's fact sheet before relying on any of them. They moved recently and stale figures are everywhere online. The full regional breakdown, including the tighter acquirer-level thresholds, is in Visa's VAMP thresholds for 2026.

The mistakes that quietly change your number

Assumption	What actually happens
The ratio is weighted by dollar value	It is a count. A $12 dispute and a $1,200 dispute are one event each.
My Shopify chargeback rate is my VAMP ratio	Different numerator, and a smaller, CNP-only denominator, so the same disputes read as a higher ratio.
Winning a representment removes the dispute from the ratio	It does not. A dispute counts the moment it is filed. Winning recovers the money, not the ratio entry.
A deflected dispute always stays off the count	Only "contingent on the timing of the data extract," in Visa's own wording. One deflected near month-end can still land in that month's numerator.

That is the mechanical reason deflection matters. Once an order has gone wrong, deflecting the dispute before it is filed is the only lever that touches the numerator, which is also why winning a chargeback does not fix your dispute ratio.

What to do once you know your number

A single reading tells you where you are. Run three more before you decide anything.

Drop the denominator 30%. Model your slowest month. Disputes lag the orders that caused them by weeks, so a post-peak trough combines last month's disputes with this month's smaller volume. This is the case that catches most seasonal brands off guard.

Add a promotion. Take a discount event that lifted order count 40% and assume disputes rise with it. If the ratio holds steady, your dispute rate is structural rather than volume-driven, and prevention work will move it more than growth will.

Isolate your worst SKU or channel. Pull one product line or one paid channel's events out and recalculate. A single subscription SKU or a single ad channel can carry a disproportionate share of a brand's dispute count.

Then compare what you would have to deflect against your actual monthly dispute count. If it is a small share, alerts is a targeted fix worth pursuing. If it is most of them, you have a product or fulfilment problem, and no amount of deflection will hold the ratio down for long.

The honest part

I want to be precise about what this gives you: an estimate, not the official figure. Visa computes from its own data extract. You do not have that extract, so your number and your acquirer's can differ even when your arithmetic is right. Ask your acquirer for your monthly VAMP report rather than reverse-engineering it.

The count floor is not a safe harbour either. Visa monitors acquirers on their own portfolio ratio at 50 and 70 basis points, far tighter than any merchant threshold, so an acquirer under pressure sets its own merchant limits well below 1,500 events a month. Those contractual limits, not Visa's floor, are what end up in your reserve terms.

And deflection is neither free nor guaranteed. Coverage depends on the networks you are enrolled with and whether the signal reaches you before the dispute is filed, so treat any deflection figure this calculator gives you as a target, not a promise.

Frequently asked questions

Is my Shopify chargeback rate the same as my VAMP ratio?

No. Shopify's rate is computed over your total orders and reflects only what reached your Shopify Payments account. The VAMP ratio counts TC40 fraud reports and TC15 disputes across your whole Visa acceptance, divided by settled card-not-present Visa transactions only, which is usually a smaller denominator than your total order count.

Does a chargeback I win still count against my VAMP ratio?

Yes. A dispute enters the ratio the moment it is filed. Visa's exclusions cover disputes resolved through pre-dispute solutions and TC40 fraud that qualifies for Compelling Evidence 3.0, not disputes you fought and won through representment.

What counts as a settled transaction in the VAMP denominator?

Settled card-not-present Visa transactions only, domestic and cross-border. Mastercard, Amex, PayPal, and any card-present volume are excluded from the denominator, which is why the ratio often reads higher than a simple disputes-over-orders calculation.

Is there a minimum number of disputes before VAMP applies to me?

Yes. Visa only identifies a merchant once fraud-plus-disputes clears 1,500 events a month in most regions, or 150 events plus a USD 75,000 minimum in CEMEA. Below that floor, the ratio alone does not trigger identification, though your acquirer may still hold you to a stricter internal limit.

What to calculate this week

Pull one month, not a quarter, and get four numbers: settled Visa card-not-present transactions, TC15 dispute count, TC40 fraud count, and the same figures your acquirer holds.

Compare your calculation to theirs. If the gap is large, the gap is the finding, and it is usually the denominator. Then run the same four numbers for the previous two months and watch the trend, not just this month's reading.

Ask your acquirer, in writing: what ratio are you holding us to, and is it Visa's threshold or your own? Get the answer on paper before you spend anything trying to move it.