About CalcSun
CalcSun is a free collection of online tools that answer everyday questions — from "what's my US shoe size?" to "how much is 100 USD in EUR?" — quickly, accurately, and without registration.
What We Offer
Fashion Tools
International clothing, shoe and ring size converters, plus a body measurement calculator covering US, UK, EU, China, Japan and Korea standards.
Converters
Length, weight, temperature, area and currency conversion — with daily-updated exchange rates for 40+ world currencies.
Location Tools
US ZIP code lookup, world time zones for 33,000+ cities, country code reference for 250 countries, and city-to-city distance calculation.
Calculators
Percentage, profit, margin, discount, tax, age, date, loan, interest, compound interest and ROI calculators with clear formulas and examples.
Our Principles
- Free, forever — every tool works without registration or payment.
- Fast — pages are lightweight and results are instant.
- Transparent — we show the formula behind every calculation, so you can verify the math yourself.
- Private — the values you enter are used only to compute your result. See our Privacy Policy.
Data Sources
We believe good tools start with good data:
- Geographic and postal data from GeoNames (CC BY 4.0)
- Currency exchange rates from open market data, updated daily
- Time zone data from the IANA Time Zone Database
- Size charts compiled from published industry sizing standards
Contact Us
Found an error, have a suggestion, or want to request a new tool? We'd love to hear from you:
Email: contact@calcsun.com
Currently serving 31 free tools — and growing.