Before you sell,
check what you keep.
Marketplace fees, shipping, VAT, customs duty. The numbers Korean online sellers check every day, calculated for free with no sign-up. Built by a seller for running our own store.
Seller tools
We keep adding more. Your inputs are saved only in your own browser.
Margin calculator
What you keep after fees, shipping and VAT
10% + 10% off is really 19%Discount calculator
Sale price, rate and stacked discounts
25% margin → 400% ROASBreak-even ROAS
The minimum ROAS that avoids a loss
14 categories at a glanceCoupang fees by category
Rates and real amounts per category
100 products, auto-calculatedExcel margin sheet
Free template that does the math
11,000 = 10,000 + 1,000 VATVAT calculator (10%)
Split out or add 10% Korean VAT
Under 48M KRW: no VAT to payVAT estimator
What you will owe at filing time
2,438 KRW unit, 3,807 landedImport sourcing cost
Real cost per unit from 1688
Duty-free up to 200 USD (US)Duty & VAT on imports
Duty-free limit, duty and VAT
40×30×25 cm box bills as 5 kgVolumetric weight
Chargeable weight and CBM from box size
Seller guides
The rules behind the calculator numbers, explained with examples.
About bymay
bymay is a Korean online multi-category store curating everyday products, from clothing and accessories to books, toys, and computer and office supplies. We compare supplier catalogues ourselves and only stock products whose quality and price add up.
Catalogue collection
We gather product data from many suppliers into one format.
Sourcing & data
We compare prices and terms across suppliers and manage product information.
Pricing & margin
We set fair prices from cost, shipping and fees.
Reviews & marketing
We find improvements in customer reviews and refine product descriptions.
We automate repetitive work with AI (Claude); people make the decisions.
Contact
For listings, partnerships or suggestions for the tools, please email us. English is welcome.
adminsoohyeong@bymay.co.kr