Discount Calculator

A free collection of shopping calculators for discount percentage, unit price comparison, import customs duty, and credit card installment fees.

Calculate Discount Compare Unit Prices

TL;DR

ShopCalc is a free collection of shopping calculators that run right in your browser with no sign-up or install, instantly computing discount percentage, unit price, import customs duty, and credit card installment fees.

All calculations run in your browser, and your inputs are never sent to or stored on a server.

Shopping Calculators

Discount Calculator

Find the sale price from the original price and discount rate, or reverse-calculate the discount rate from the original and sale price.

Unit Price Comparison

Convert several products with different sizes and prices to a per-100g or per-unit price to find the cheapest.

Import Customs Duty Calculator

Calculate duty and VAT from item value and shipping, with de minimis thresholds (US $200 / other $150).

Credit Card Installment Fee Calculator

Compute total interest, monthly payment, and grand total from the amount, term in months, and fee rate.

Shopping Guides

Import Customs Duty: De Minimis Thresholds and How to Calculate

De minimis limits (US $200, other $150), the taxation trigger, and how to compute duty and VAT - all in one place.

Why Use ShopCalc

Free, no install - Use it right in your browser with no sign-up or app to download.
No personal data collected - Every calculation runs in your browser and your inputs are never sent to a server.
Built for real shopping - Compare unit prices in-store or online and check de minimis thresholds for imports.
Formulas shown - Each calculator includes the formula, the method, and links to official sources.

Each result is an estimate for reference only; confirm exact duties and taxes with the Korea Customs Service.

Last updated: 2026-06-25