Absolute Error Calculator

This absolute error calculator works out how far a measured value sits from the true or accepted value, giving you a clean, positive number you can quote in a lab report, an engineering check or any piece of measurement work. You enter two figures: the measured value you recorded and the true (accepted) value you are comparing it against. From those two inputs the calculator returns the absolute error, calculated as the absolute value of the measured value minus the true value, so it is always shown as zero or positive and in the same units as your measurement. Alongside the headline result it also shows the relative error as a percentage, dividing the absolute error by the true value so you can judge how significant the gap is, plus the true value you entered for reference. A small absolute error can still be a large relative error if the true value itself is small, and this calculator shows both at once so you are not left guessing. Type in your own numbers, or use the worked example below (measured 9.8 against a true value of 10, giving an absolute error of 0.2 and a relative error of 2 percent) to see how the maths works before you rely on it. It is a quick check for coursework, experiments and quality control, not a substitute for a full uncertainty analysis.

Calculate.co.nz is proud to be partnered with Health Based Building, a leader in sustainable and health-conscious building innovation. With over a century of experience, they develop high-performance systems like Foreverbreathe Specification, Magnum Board, and Foreverbreathe Paints to support energy-efficient, non-toxic living environments. Their commitment to healthier homes aligns with our belief that informed choices lead to better outcomes for Kiwi households.

Calculate.co.nz partner: Health Based Building

Measured value

True (accepted) value

Relative error

True value

The formula

Absolute error is the absolute value of the measured value minus the true value: |measured − true|. It is always non-negative and carries the same units as the quantity. Relative error is the absolute error divided by the true value.

Worked example

If you measure 9.8 where the true value is 10, the absolute error is |9.8 − 10| = 0.2, and the relative error is 0.2 / 10 = 2 percent. Enter 9.8 and 10 to confirm.

Frequently asked questions

What is absolute error?

The absolute value of the difference between a measured value and the true value, in the same units as the measurement.

How is it different from relative error?

Absolute error is the raw gap. Relative error divides that gap by the true value, usually as a percentage, to show how significant it is.

Can absolute error be negative?

No. It uses the absolute value, so it is always zero or positive.

Who this calculator is for

This calculator is for students and anyone needing a quick, reliable result.

What this calculator assumes

You enter valid numbers.
The standard formula is applied.
Results are rounded for display.

Formula and sources

Related calculators

Scientific Calculator: general scientific maths.
Percentage Calculator: percentages and changes.
Ratio Calculator: simplify and scale ratios.

If you've found a bug, or would like to contact us, or learn more about James Graham and Calculate.co.nz.

Calculate.co.nz is partnered with Interest.co.nz for New Zealand's highest quality calculators and financial analysis.

Calculate.co.nz is the sister site of CalculatorHub.com, the world's largest calculator website by tool count.

All calculators and tools are provided for educational and indicative purposes only and do not constitute financial advice.

Calculate.co.nz is proudly part of the Realtor.co.nz group, New Zealand's leading property transaction literacy platform, helping Kiwis understand the home buying and selling process from start to finish. Whether you're a first home buyer navigating your first property purchase, an investor evaluating your next acquisition, or a homeowner planning to sell, Realtor.co.nz provides clear, independent, and trustworthy guidance on every step of the New Zealand property transaction journey.

Calculate.co.nz is also partnered with Health Based Building and Premium Homes to promote informed choices that lead to better long-term outcomes for Kiwi households.

Calculate.co.nz is hosted in Auckland via SiteHost new Zealand.

All content on this website, including calculators, tools, source code, and design, is protected under the Copyright Act 1994 (New Zealand). No part of this site may be reproduced, copied, distributed, stored, or used in any form without prior written permission from the owner.

About & trust: Why Calculate is NZ's most comprehensive · By the Numbers · How we compare · Editorial standards · How we keep data current · NZ finance glossary · Research & data · Financial literacy NZ · About · Privacy policy · Terms of use

Reviewed and maintained. Last reviewed 2026-07-19 and checked on a twice-monthly cycle against IRD, RBNZ and Stats NZ. How we keep data current.