CalculationTime

Percent Error Calculator

Calculate percent error between an experimental or measured value and an accepted reference value, with absolute and signed error shown clearly.

Live math canvas

Your numbers, formula and explanation together

Percent Error Calculator: 198 percent. Percent Error Calculator uses the declared inputs to produce a transparent default result. Measured value: 98; Accepted/reference value: 100; primary comparison: 98 and 100.

Formula applied

The exact method behind this answer

CalculationTime keeps the method visible so the number can be checked instead of blindly trusted.

Error = measured value − accepted value. Absolute error = |measured value − accepted value|. Percent error = (absolute error ÷ |accepted value|) × 100. Signed percent error = ((measured value − accepted value) ÷ |accepted value|) × 100.
  1. Apply the formulaError = measured value − accepted value. Absolute error = |measured value − accepted value|. Percent error = (absolute error ÷ |accepted value|) × 100. Signed percent error = ((measured value − accepted value) ÷ |accepted value|) × 100.198 percentPercent Error Calculator uses the declared inputs to produce a transparent default result. Measured value: 98; Accepted/reference value: 100; primary comparison: 98 and 100.

Your live breakdown

Current inputs in the calculation

These values come from the controls above and update when the calculator changes.

Measured value
98
The observed, experimental or calculated value you want to compare.
Accepted/reference value
100
The standard, expected or reference value used as the comparison base.

Resulting answer

198 percent

Percent Error Calculator uses the declared inputs to produce a transparent default result. Measured value: 98; Accepted/reference value: 100; primary comparison: 98 and 100.

Answer
198 percent
Live support
Percent Error Calculator uses the declared inputs to produce a transparent default result. Measured value: 98; Accepted/reference value: 100; primary comparison: 98 and 100.

Assumptions used

What this answer assumes

Use absolute percent error for size and signed percent error for direction. Check the source of the reference value.

  • The accepted/reference value is treated as the comparison base.
  • Percent error is undefined when the accepted value is zero because the formula would divide by zero.
  • The main result uses absolute percent error so overestimates and underestimates are comparable.
  • Signed percent error is shown to indicate whether the measured value is above or below the reference value.
  • This is transparent general arithmetic; measurement uncertainty, calibration and laboratory method rules are not certified by this page.

Master’s Tip

How to use the result well

Master’s Tip: write down the source of the accepted value before judging the percent error. In labs, QA checks and estimating work, a small arithmetic error can still be unacceptable if the reference value, instrument tolerance or calibration method is wrong.

Printable record

What belongs in the saved calculation

Save the inputs, result, formula, assumptions, page URL and date together so the calculation can be reviewed later.

Measured value
98
The observed, experimental or calculated value you want to compare.
Accepted/reference value
100
The standard, expected or reference value used as the comparison base.

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Formula

Error = measured value − accepted value. Absolute error = |measured value − accepted value|. Percent error = (absolute error ÷ |accepted value|) × 100. Signed percent error = ((measured value − accepted value) ÷ |accepted value|) × 100.

Worked example

Measured value = 98 and accepted value = 100. Error = 98 − 100 = −2. Absolute error = 2. Percent error = 2 ÷ 100 × 100 = 2.00%. Signed percent error is −2.00%, showing the measurement is below the reference.

Professional note

Master’s Tip: write down the source of the accepted value before judging the percent error. In labs, QA checks and estimating work, a small arithmetic error can still be unacceptable if the reference value, instrument tolerance or calibration method is wrong.

Regional and unit assumptions

Standard or basis: transparent relative-error arithmetic using the accepted value as the denominator. No laboratory, engineering or compliance standard is claimed unless the user supplies the governing tolerance separately.

Assumptions and limitations

Methodology & Accuracy

How this calculator is checked

CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.

Formula used

Error = measured value − accepted value. Absolute error = |measured value − accepted value|. Percent error = (absolute error ÷ |accepted value|) × 100. Signed percent error = ((measured value − accepted value) ÷ |accepted value|) × 100.

Standard or basis

Standard or basis: transparent relative-error arithmetic using the accepted value as the denominator. No laboratory, engineering or compliance standard is claimed unless the user supplies the governing tolerance separately.

Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.

Master's Tip

Master’s Tip: write down the source of the accepted value before judging the percent error. In labs, QA checks and estimating work, a small arithmetic error can still be unacceptable if the reference value, instrument tolerance or calibration method is wrong.

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Questions

What is percent error?

Percent error expresses the absolute difference between a measured value and an accepted value as a percentage of the accepted value.

What is the percent error formula?

Percent error = |measured value − accepted value| ÷ |accepted value| × 100.

Why does the calculator show signed error too?

Absolute percent error shows size. Signed percent error also shows direction, so you can see whether the measured value is above or below the reference.

Can accepted value be zero?

No under the standard percent-error formula. Dividing by zero is undefined, so use an absolute error or another comparison method when the reference value is zero.

Is percent error the same as percent change?

No. Percent error compares a measured value with an accepted reference value. Percent change compares a new value with an original baseline.

Calculation note

Percent error is common in science classes, quality checks, estimating and measurement work because it turns a raw difference into a relative comparison. The arithmetic is simple, but the accepted reference value and tolerance rule decide whether the error is meaningful.

Relative error depends on the reference value

A difference of 2 units can be small or large depending on the accepted value. Two units away from 100 is a 2% error, while two units away from 10 is a 20% error. That is why the denominator is visible in the calculator.

Absolute size and direction answer different questions

Many classroom formulas report absolute percent error so overestimates and underestimates can be compared by size. The signed result is still useful because it shows whether the measured value is above or below the reference.

Arithmetic does not replace uncertainty or calibration

Percent error can highlight the gap between a result and a reference, but it does not prove why the gap happened. Real measurement work may require uncertainty budgets, calibration checks, repeat measurements and a defined tolerance rule.

Sources and further readingNIST: Uncertainty of Measurement ResultsNIST/SEMATECH e-Handbook of Statistical Methods: Measurement Process Characterization