Pythagorean Theorem Calculator

Find the hypotenuse of a right triangle from its two legs. Enter your values below to calculate instantly, then use the explanation and example to understand the result.

Enter your values

Hypotenuse c

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What this Pythagorean Theorem Calculator does

Find the hypotenuse of a right triangle from its two legs. It is designed to give a quick answer while still showing enough context to understand what the number means and what assumptions can affect it.

Inputs usedLeg a, Leg b

Main resultHypotenuse c

Runs locallyCalculation is performed in your browser; the page does not need an account to calculate.

How to use the calculator

Enter each value using the unit shown beside the field.
Select Calculate to update the result.
Read the result together with the unit, assumptions and interpretation on this page.
Change one input at a time when comparing scenarios so you can see what actually drives the answer.

Formula and calculation method

c = √(a² + b²)

Worked example

With the example inputs Leg a = 3, Leg b = 4, the calculator returns approximately 5.

How to interpret the result

Mathematical calculators are most useful when the exact relationship is visible. Check signs, zeros, domain restrictions and whether the problem expects an exact or rounded answer.

For schoolwork or technical use, keep extra digits during the calculation and round only the final answer.

Accuracy, inputs and rounding

The arithmetic is deterministic: the same valid inputs produce the same answer. A realistic result still depends on the quality of the values you enter. XpressCalculator keeps units next to inputs and rounds displayed results for readability. When precision matters, keep more source precision and avoid rounding intermediate values.

Important: This page is an informational calculator. For medical, financial, electrical, engineering, tax, legal or safety-critical decisions, verify the assumptions and current rules with an authoritative source or qualified professional.

Frequently asked questions

What does the Pythagorean Theorem Calculator calculate?

Find the hypotenuse of a right triangle from its two legs.

Why can another calculator show a different answer?

Different calculators may use different formulas, defaults, rounding rules, unit conventions or assumptions. Match the inputs and method before comparing results.

Can I use decimal values?

Yes, where the input field accepts numbers. Use the precision supported by your source data rather than adding unnecessary decimal places.

Does XpressCalculator save the values I enter?

The calculation logic on this page runs in your browser. Standard site analytics or advertising services may still process technical usage data as described in the Privacy Policy.

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Editorial review: Formula, units, interface and explanatory content reviewed for consistency on September 4, 2026. See our Methodology and Accuracy Policy.