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Last updated on October 16, 2025

Accuracy

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The degree to which a measurement resembles the actual value is known as accuracy. Accuracy is about how close a measurement is to the true value. Every measurement involves some level of uncertainty.

Accuracy for US Students
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What is Accuracy?

Accuracy is the degree to which the measurement resembles the true value. Accuracy is one example of good measurement quality. When buying a pound of bread from a supermarket, we can say that the measurement is accurate if the weight of the pound matches the printed values.
Although it is not computed directly, accuracy can be computed using the errors. High accuracy is indicated by a measurement with few errors.
 

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What is the Formula for Accuracy?

The following percent error formula determines the accuracy:
Percent Error={(Measured value-True value)/True value} × 100
This formula gives the accuracy as a percentage. A smaller percent error means a more accurate result.

 

 

What are the Types of Accuracy?


A system’s accuracy can be classified into three types they are:
Point Accuracy
Accuracy as Percentage of Scale Range
Accuracy as Percentage of True Values

 

 

Point Accuracy


The accuracy of an instrument at a particular point on its scale is referred to as point accuracy. It doesn’t represent the instrument’s overall accuracy over its whole range. It merely indicates that an instrument’s accuracy refers to how close its measurement is to the true value at a given time.

 

 

Accuracy as Percentage of Scales Range


The consistency of the instrument’s scale is the foundation for this kind of accuracy. Take a thermometer with a scale that goes up to 100°C. If it has an accuracy of ± 0.5, it means the reading could be off by up to ±0.5°C. For example, A thermometer with ± 0.5% accuracy on a 100°C scale means it can be off by up to  ±0.5°C (0.005 × 100 = ±0.5 °C). So, any reading may be 0.5 °C.

 

 

Accuracy as Percentage of True Values


This accuracy metric evaluates the degree to which the measured value resembles the true value. Instruments usually have an acceptable margin of error, usually ±0.5 percent of the actual value. This criterion helps in assessing an instrument’s accuracy with regard to the object it is measuring.
 

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How to Determine Accuracy of Measurement

To determine whether our data is accurate, the following actions can be taken:
Step 1: Collect and organize data 

Step 2: Determine the mean value.
Average value=sum of datanumber of measurements
Step 3: Determine the percentage of error.
Percent error= accepted value - measured valueaccepted value× 100
Step 4: Find the absolute deviations for each measurement, using the formula.
Absolute deviation=measured value-average value

Step 5: Calculate the average of all deviations.
The average deviation is calculated by adding the absolute deviations of all the measurements together and dividing the result by the total number of measurements. 

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Factors Determining Accuracy of Measurement

The following elements should be considered when assessing the precision of our data:

 

 

Error types


 Accuracy can be evaluated by analyzing different types of errors. It shows how much the measured data deviates from the actual values. Two common ways to assess accuracy are by calculating the errors.

Absolute error: The absolute error is the discrepancy between a measured value and an actual value. You may be able to ascertain how closely your measurement corresponds to the item’s actual value by looking at the absolute error.
Absolute error=Measured value-Actual value

 

Relative error: This shows how much the measurement itself deviates from the absolute error. This can be helpful when determining the magnitude of the error relative to the actual value. Our measurement is usually accurate if the relative error is smaller.
Relative error={Absolute error}{Measured value}

 

 

Tools of Measurement


One factor that may have an impact on the accuracy of our findings is the measurement techniques we use when gathering data. Measurement devices that can gather data in smaller steps tend to produce more accurate results.

 

 

Significant Figures


When measuring accuracy, it is important to consider that the significant figures are the digits in a measurement that contribute to its accuracy. When collecting data, you can only record the number of digits that your measurement equipment can handle.
 

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Real Life Examples on Accuracy

Accuracy in real life means how close a measured value is to the true value. Let us see how accuracy helps in real life.

Calibration of medical thermometers
A thermometer is used in hospitals to measure a patient’s body temperature. If it shows a 98.6°F result for a healthy person, it is considered accurate. This accuracy helps doctors make correct diagnoses and avoid false symptoms.
GPS location monitoring
A delivery app uses the GPS to track the driver’s location. If the pin shows the driver exactly at your doorstep. The system is considered accurate. This level of accuracy helps ensure on-time deliveries and a better customer experience.
Laboratory test results
The equipment and technique employed in a diagnostic lab are accurate if a blood test correctly indicates the patient’s blood sugar level as 90 mg/dL, when that is the actual value. This promotes appropriate medical care.
Weighing products in stores
Fruits are weighed on digital scales at a supermarket. The scale is accurate if 1 kg of apples is put in, and it reads 1 kg. Fair pricing and client trust are thus guaranteed.
Sports timing devices
The timing system records an athlete’s time at the end of a 100-meter race as 9.58 seconds, which is precisely the same as the official record and the manual stopwatch. This demonstrates that the timing system meets competition standards for accuracy and dependability.
 

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Common Mistakes and How to Avoid Them in Accuracy

While working with measurements and accuracy, students make mistakes that affect the result. Let us look at the mistakes and how to quickly correct them.
 

Mistake 1

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Confusing precision with accuracy
 

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 Understanding that consistent measurements aren't always correct. Always compare the result with the true or standard value to ensure accuracy.
 

Mistake 2

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Using instruments that are not calibrated
 

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 Before using any measuring tool, make sure it’s properly calibrated. For example, a weighing scale should show zero when nothing is placed on it.
 

Mistake 3

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Ignoring systematic errors
 

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Look for a pattern in your results. If all measurements are consistently off, check for equipment or setup issues that may cause systematic errors.
 

Mistake 4

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Not managing environmental influences
 

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 Know that variations in humidity or temperature can have an impact on readings. Make adjustments for variations or take measurements in a controlled environment. 
 

Mistake 5

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Making a single measurement
 

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Always take multiple measurements and average them. This reduces the impact of random errors and gives a more reliable result.

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Solved Examples On Accuracy

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Problem 1

When a standard weight of 2 kg is used to test a scale, the result is 2.05 kg. Is the scale correct?

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2.05 kg ≠ 2.00 kg
 

Explanation

Accuracy refers to how close a measurement is to the actual value. In this example, the scale shows that a reading is 0.05 kg higher than the true weight. So the measurement is slightly off and considered inaccurate.
 

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Problem 2

At sea level, a thermometer reads 100°C for boiling water. Is it true?

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 Yes, 100 °C 
 

Explanation

The thermometer is considered accurate because it shows exactly 100°C, which matches the true value is.
 

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Problem 3

The location that a GPS indicates is three meters away from the real point. Is it considered accurate?

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GPS accuracy is typically within 5 meters.
 

Explanation

In this, the GPS is considered accurate because the small error within 5 meters is an acceptable range.
 

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Problem 4

A student calculates that a 30 cm ruler is 29.8 cm long. Is the measurement precise?

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Yes, the measurement is precise
 

Explanation

The measurement is close to the actual length, so it is accurate, but precision refers to consistency across repeated measurements, which is not shown here.
 

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Problem 5

For a race that officially took 12.00 seconds, a stopwatch registers 12.01 seconds. Is the stopwatch precise?

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The stopwatch shows 12.01 seconds, while the official time is 12.00 seconds, making the difference just 0.01s.
 

Explanation

The stopwatch is considered accurate, but we cannot determine its precision from a single reading. Precision requires repeated measurements.

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FAQs On Accuracy

1.What does accuracy mean?

The state or attribute of being true, accurate, or precise; the absence of error or flaw; accuracy; or correctness.
 

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2.How to measure accuracy?

Comparing calculated or measured values to a recognized or accepted standard, usually represented as a percentage or a margin of error.
 

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3.List the types of accuracy.

Point accuracy, accuracy as a percentage of true value, and accuracy as a percentage of scale range.
 

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4.What is the accuracy principle?

Requires all the reasonable steps to erase or rectify inaccurate data without delay.
 

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5.What is the formula for accuracy?

          Percent Error={(Measured value-True value)/True value} × 100
 

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Jaskaran Singh Saluja

About the Author

Jaskaran Singh Saluja is a math wizard with nearly three years of experience as a math teacher. His expertise is in algebra, so he can make algebra classes interesting by turning tricky equations into simple puzzles.

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Fun Fact

: He loves to play the quiz with kids through algebra to make kids love it.

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