EStore Tools

BNPL Merchant Fee Calculator

Weigh Klarna, Afterpay or Affirm's fee against the average-order-value lift they claim, so you can see if it actually pays off.

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Your numbers

Without BNPL
$

What you'd pay a regular card processor on that same order.

%
$

Profit before fees, as a share of the selling price. Used to value the extra revenue BNPL might bring.

%
With BNPL

Rates are negotiated per merchant and not published in full. Pick a starting point, then overwrite it with your own contract's rate below.

%
$

Klarna and Affirm both publish merchant-reported uplift figures (Klarna cites over 20%, an Affirm-commissioned study cited 87%). These are vendor marketing claims, not independent research: start conservative and check your own before/after data.

%
Your volume
orders
%

Your result · updates as you type

Extra profit per BNPL order

$2.97

Comparing a $96.00 order on Klarna with a $80.00 order on a normal card. At 90 BNPL orders a month that's $267.

Profit per order, normal card
$29.38
Profit per order, Klarna
$32.35
Monthly net effect
$267

Published ranges run 3.29% to 5.99% + $0.30, with the low end for merchants doing $5M+ a year. Confirm your own contracted rate and measure your actual AOV change over a few weeks before rolling BNPL out everywhere.

Profit per order: normal card vs BNPL
Normal card
$29.38
Klarna
$32.35

Breakdown

Without BNPL
$80.00 order, card fee (2.9% + $0.30)
−$2.62
Profit per order
$29.38
With Klarna
$96.00 order (+20% AOV), fee (5.99% + $0.30)
−$6.05
Profit per order
$32.35
Net effect per BNPL order
$2.97
At 90 of 300 orders using it
$267

Why BNPL fees need an uplift assumption

Klarna, Afterpay and Affirm all charge more than a normal card, sometimes a lot more. They argue it pays for itself because shoppers spend more when they can split the payment. This calculator makes you put a number on that uplift instead of taking it on faith, so you can see the real net effect on profit.

Net effect per BNPL order = (uplifted order × margin − BNPL fee) − (base order × margin − card fee)

Example: the default numbers (Klarna, $80 base order, 40% margin, 20% uplift)

Normal card: $80 order, 2.9% + $0.30 fee
Profit $29.38
Klarna: $96 order (+20%), 5.99% + $0.30 fee
Profit $32.35

Klarna nets $2.97 more profit on this order. At 90 of 300 monthly orders using it, that's $267 a month, if the 20% uplift actually happens.

Klarna and Affirm both publish merchant-facing uplift figures (Klarna cites over 20%, an Affirm-commissioned study cited 87%). Treat those as marketing claims, not guarantees: they're the provider's own numbers, not independent research, and they vary hugely by category and price point.

Fee ranges collected 30 Sep 2026

ProviderPublished range
Klarna3.29% to 5.99% + $0.30, lower end for merchants doing $5M+ a year
AfterpayAbout 4.99% + $0.30 direct, around 6% + $0.30 through some integrations
AffirmRoughly 2% to 3% for short 0% terms, much higher for long interest-free financing on big-ticket items

None of these providers publish one flat rate: your real fee is negotiated based on volume, category and the plan lengths you offer. Overwrite the defaults with the rate on your own contract before trusting the result.

Testing it properly

  1. 01

    Start with the 0% uplift preset

    See the pure fee gap first, so you know exactly how much uplift you need just to break even.

  2. 02

    Run a real test

    Turn BNPL on for a slice of traffic or a season, then compare average order value on BNPL orders with your normal orders.

  3. 03

    Come back and rerun this

    Swap in your measured uplift and your contracted fee for an honest read on whether it's paying for itself.

Questions people ask

How much does Klarna charge merchants?

Published ranges run from about 3.29% + $0.30 for high-volume merchants up to 5.99% + $0.30. Your actual rate is set in your merchant agreement, not published in full.

Does offering BNPL really increase average order value?

Klarna and Affirm both publish uplift figures in that direction, but those are the providers' own marketing statistics. Measure your own before-and-after data rather than assuming their number applies to you.

Is Afterpay cheaper than Klarna?

Published rates are similar, both in the high single digits including the fixed fee. The real difference usually comes down to what you negotiate at your volume, and which one your customers already have an account with.

Can I add Klarna or Afterpay to Shopify or WooCommerce?

Yes, both have official apps and plugins for Shopify and WooCommerce that add the option at checkout alongside your normal payment methods.

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Want this builtinto your store?

I'm Emmanuel, a Shopify and WooCommerce developer. If this tool pointed at something you'd rather have fixed for you (a faster store, cleaner product data, a migration, a custom feature), send me a note.

Emmanuel Asika

Emmanuel Asika

Shopify & WooCommerce developer, Dublin

I build and fix online stores: new builds, migrations, speed, SEO and the custom bits apps can't do.

hello@emmanuelasika.com
See my work

Last reviewed 30 September 2026.

Sources: Klarna: Pricing and merchant fees (varies by agreement) · Afterpay (Cash App): For merchants · Affirm: Pricing for business