Pressure Sensor Accuracy Explained: Accuracy, Precision, Repeatability & Error Sources

Introduction

Pressure sensors are used in virtually every industry where pressure measurement affects safety, process control, product quality, or system performance. Whether monitoring hydraulic pressure in industrial equipment, measuring airflow in HVAC systems, controlling fuel pressure in automotive applications, or regulating medical devices, measurement accuracy directly influences system reliability.

However, many engineers and buyers misunderstand pressure sensor specifications. Terms such as accuracy, precision, repeatability, hysteresis, linearity, and temperature drift are often used interchangeably even though they describe different aspects of sensor performance.

As a result, engineers may over-specify sensors and increase costs unnecessarily, or under-specify sensors and create measurement errors that affect system operation.

This guide explains how pressure sensor accuracy is defined, how manufacturers calculate accuracy specifications, the difference between key performance parameters, and how to choose the appropriate accuracy level for your application.

Quick Answer: What Is Pressure Sensor Accuracy?

Pressure sensor accuracy describes how closely a sensor's measured output matches the true pressure value.

A sensor with higher accuracy produces measurements that are closer to the actual pressure.

Accuracy is affected by multiple error sources, including:

· Linearity error

· Hysteresis

· Repeatability

· Temperature effects

· Calibration uncertainty

· Long-term drift

Because several factors contribute to measurement uncertainty, accuracy specifications are often expressed as a percentage of full scale (FS).

For example:

· ±1.0% FS

· ±0.5% FS

· ±0.25% FS

· ±0.1% FS

The smaller the number, the more accurate the sensor.

Why Pressure Sensor Accuracy Matters

Measurement accuracy influences:

· Process control quality

· Product consistency

· Equipment safety

· Energy efficiency

· Regulatory compliance

· Maintenance costs

Even small pressure errors can create significant operational issues.

For example:

What Is the Difference Between Accuracy and Precision?

Accuracy and precision are not the same.

Accuracy

Accuracy indicates how close measurements are to the true value.

Example

Actual pressure:

100 psi

Measured value:

99.8 psi

The sensor is highly accurate.

Precision

Precision describes how consistently measurements repeat.

Example

Five readings:

· 95 psi

· 95 psi

· 95 psi

· 95 psi

· 95 psi

The readings are very precise but not accurate if the actual pressure is 100 psi.

Accuracy vs Precision Comparison

An ideal pressure sensor provides both high accuracy and high precision.

What Is Repeatability?

Repeatability describes a sensor's ability to produce the same output when the same pressure is applied repeatedly under identical conditions.

Example

Applying 100 psi five times:

· 100.01 psi

· 100.02 psi

· 99.99 psi

· 100.01 psi

· 100.00 psi

Excellent repeatability.

Repeatability is critical in:

· Industrial automation

· Test equipment

· Laboratory instruments

· Quality control systems

What Is Resolution?

Resolution is the smallest pressure change a sensor can detect.

For example:

A sensor with 0.01 psi resolution can detect changes as small as 0.01 psi.

Resolution does not guarantee accuracy.

A sensor can have excellent resolution but poor calibration.

What Is Hysteresis?

Hysteresis occurs when the sensor produces different outputs for the same pressure depending on whether pressure is increasing or decreasing.

Example

Increasing pressure to 100 psi:

Output = 100 psi

Decreasing pressure to 100 psi:

Output = 99.7 psi

The difference represents hysteresis error.

Causes

· Material elasticity

· Mechanical friction

· Internal stress

What Is Linearity?

Linearity describes how closely sensor output follows a straight-line relationship across the measurement range.

A perfectly linear sensor would generate proportional output throughout the entire pressure range.

Non-linearity introduces measurement error, especially near the upper and lower limits of the pressure range.

What Is Temperature Drift?

Temperature changes can affect sensor output even when pressure remains constant.

Temperature drift may occur due to:

· Diaphragm expansion

· Semiconductor characteristics

· Electronic component variation

Common specifications include:

· Zero temperature coefficient

· Span temperature coefficient

Temperature compensation circuits help minimize these effects.

How Manufacturers Define Accuracy

Manufacturers typically define accuracy using a combination of several error terms.

These may include:

· Non-linearity

· Hysteresis

· Repeatability

Some manufacturers specify:

BFSL Accuracy

Best Fit Straight Line method.

Provides smaller error values.

Terminal Accuracy

Includes all operating errors.

Provides a more realistic representation of field performance.

Always review datasheets carefully when comparing products.

Understanding Accuracy Specifications

Most pressure sensor datasheets express accuracy as a percentage of full scale (FS).

What Does ±1% FS Mean?

For a 0–100 psi sensor:

Accuracy:

±1 psi

Possible reading:

99–101 psi

What Does ±0.5% FS Mean?

For a 0–100 psi sensor:

Accuracy:

±0.5 psi

Possible reading:

99.5–100.5 psi

What Does ±0.25% FS Mean?

For a 0–100 psi sensor:

Accuracy:

±0.25 psi

Possible reading:

99.75–100.25 psi

Accuracy Comparison

Major Sources of Pressure Measurement Error

Pressure sensor accuracy is affected by many factors.

Temperature Variation

The most common source of measurement error.

Overpressure Exposure

Can permanently deform sensing elements.

Mechanical Vibration

Creates signal noise.

Electrical Interference

Introduces measurement instability.

Improper Installation

Poor mounting practices can distort measurements.

Calibration Drift

Sensor characteristics gradually change over time.

Media Compatibility Issues

Corrosive fluids can damage sensing elements.

How to Improve Pressure Measurement Accuracy

Several best practices help improve system performance.

Select Appropriate Pressure Range

Operate near the middle of the measurement range whenever possible.

Avoid Excessive Overpressure

Use snubbers or pressure protection devices.

Use Temperature Compensation

Select sensors designed for expected operating temperatures.

Calibrate Regularly

Periodic calibration reduces long-term drift.

Minimize Electrical Noise

Use proper grounding and shielding.

Install Correctly

Follow manufacturer recommendations for mounting and plumbing.

Accuracy Requirements by Industry

Different industries require different accuracy levels.

Choosing accuracy beyond application requirements often increases cost without improving system performance.

How Accurate Does Your Pressure Sensor Really Need to Be?

A common mistake is assuming that the highest accuracy sensor is always the best choice.

In reality:

· HVAC applications may only require ±1% FS.

· Hydraulic equipment often uses ±0.5% FS.

· Medical and laboratory systems may require ±0.25% FS or better.

Selecting accuracy based on actual application requirements usually provides the best balance between performance and cost.

Conclusion

Pressure sensor accuracy is determined by much more than a single number on a datasheet. Factors such as repeatability, hysteresis, linearity, temperature drift, and calibration all influence real-world measurement performance.

Understanding these concepts helps engineers interpret specifications correctly, compare sensor technologies more effectively, and select the appropriate sensor for each application.

Rather than simply choosing the most accurate sensor available, the best approach is to match accuracy requirements to the needs of the application, ensuring optimal performance, reliability, and cost efficiency.

Reliable Pressure Sensor Solutions from SAFTTY

Understanding how pressure sensors work is the first step toward selecting the right sensing solution.

SAFTTY offers a comprehensive range of pressure sensors designed for industrial automation, HVAC systems, hydraulic equipment, water treatment systems, medical devices, and OEM applications.

Key benefits include:

· High accuracy and repeatability

· Excellent long-term stability

· Wide pressure range options

· Stainless steel and ceramic sensing technologies

· Multiple output signals including 4–20mA, voltage, and digital interfaces

· OEM and ODM customization support

Whether you require standard industrial sensors or application-specific pressure measurement solutions, SAFTTY can help you select the most suitable technology for your project.

Learn more about SAFTTY pressure sensor solutions or contact our engineering team for technical assistance.

Frequently Asked Questions

What is considered good pressure sensor accuracy?

For most industrial applications, ±0.5% FS is considered a good balance between cost and performance.

Is ±0.25% FS significantly better than ±0.5% FS?

Yes. It cuts maximum measurement error in half.

What affects pressure sensor accuracy most?

Temperature variation is often the largest source of measurement error.

Can calibration improve accuracy?

Yes. Calibration reduces measurement error and compensates for drift.

What is the difference between repeatability and accuracy?

Repeatability measures consistency, while accuracy measures closeness to the true value.

Why do pressure sensor specifications use full scale?

Full-scale accuracy provides a consistent method for comparing sensors across different pressure ranges.