Rounding Calculator
Round numbers with half-up, half-even (banker's), up, down, ceiling and floor using exact decimal maths. Free and private: runs in your browser.
Enter numbers and the decimal places to compare rounding modes side by side, next to what JavaScript's float rounding gives.
Numbers are checked locally in your browser and never sent anywhere. Use test data, not real customer details.
Use cases
- Validate test data for payment and banking flows.
- Catch typos in account and card details before calling a provider API.
- Explain money-handling rules to your team with real examples.
Frequently asked questions
What is banker's rounding?
Half-even rounding: ties go to the nearest even digit (2.345 → 2.34, 2.355 → 2.36). It avoids an upward bias over many transactions and is the default in .NET and IEEE 754.
Is the Rounding Calculator free?
Yes. It is free with no sign-up, and it runs entirely in your browser, so your input is never uploaded or stored.
Can I use real customer data here?
Avoid it. Everything runs locally, but good practice (and PCI DSS) is to use test data outside production systems.
Related tools
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