Accuracy you can specify with confidence.
Published across the full operating range.
Six Gill wind measurement products state accuracy across their full operating range rather than at a single reference wind speed: WindSonic 60, WindSonic 75, WindObserver 65, WindObserver 70, MaxiMet and WindUltra. The figures come from testing at accredited facilities at the University of Southampton, using a statistically significant sample of each product type, and are published in the datasheet for each product.
12 m/s tells you one point.
The application needs the curve.
A single reference figure tells you how a sensor performs at that wind speed. It does not tell you what happens across the rest of the operating range, which is what a specification now has to account for.
Why the range matters
Full-range accuracy states how a sensor measures across its whole operating wind-speed range rather than at one reference wind speed. Gill publishes it for six products: WindSonic 60, WindSonic 75, WindObserver 65, WindObserver 70, MaxiMet and WindUltra.
Gill has historically stated wind speed and direction accuracy at 12 m/s. It represents a moderately strong breeze, it sits above average wind speeds across the UK and Europe, and it gives a consistent point at which sensors can be compared. For many applications that was enough.
Applications have moved. Sensors are specified for exposed infrastructure, offshore environments, aviation and mobile platforms where wind speed varies substantially, and engineers increasingly ask for accuracy data well beyond the 12 m/s reference point, particularly where the operating range extends significantly higher.
Maximum wind speed tells you the operating envelope. Full-range accuracy tells you how the sensor performs inside it.
How the figures were produced
Full-range accuracy needs evidence across the range. Gill established these figures through testing at accredited facilities at the University of Southampton, using a statistically significant sample of each product type, so the result describes the product rather than the behaviour of one instrument.
At each wind speed the sensor was rotated through 360° and its measurements compared with the reference. RMSE was then calculated from the complete set of readings, so the figure reflects performance through all angles of attack rather than in a single orientation.
- Accredited facilities at the University of Southampton.
- Statistically significant samples of each product type.
- 360° rotation at every tested wind speed.
- RMSE calculated from the complete measurement set.
- Published figures in the released datasheet and manual for each product.
The data is there to inspect, not to take on trust. Every figure on this page appears in the released product documentation.
Matching the sensor to the application
Specify the wind speeds the installation has to measure, then work through accuracy across that range, environmental exposure, integration and any approvals the application requires. The table below is a starting point rather than a ruling.
| Application | Relevant sensor | Why |
|---|---|---|
| General meteorology, building management, OEM integration | WindSonic 60 | 0 to 60 m/s measurement, low power and compact solid-state construction |
| Exposed infrastructure, bridges and traffic systems | WindSonic 75 | Extended measurement to 75 m/s in the same compact architecture |
| Marine, offshore, coastal and wind energy | WindObserver 65 | 316 stainless steel, heating, 10 Hz output and Lloyd’s Register Type Approval |
| Airports and AWOS | WindObserver 70 | FAA and CAA acceptance, heating and 70 m/s measurement range |
| Integrated weather monitoring where wind is one of several parameters | MaxiMet | 0 to 60 m/s with temperature, humidity, pressure and more in one compact station |
| UAV, USV and other mobile or severely exposed installations | WindUltra | 0 to 75 m/s in a compact, lightweight body, with the tightest low-speed direction figure of the six |
Can’t find the instrument you are looking for? Make an enquiry about full technical specifications across the product range.
Full-range accuracy explained
What is full-range accuracy?
Full-range accuracy describes measurement performance across a product’s operating wind-speed range rather than at a single reference wind speed. Gill publishes this data for six products: WindSonic 60, WindSonic 75, WindObserver 65, WindObserver 70, MaxiMet and WindUltra. The figures are published in the datasheet and manual for each product.
Does anemometer accuracy change with wind speed?
Yes. It is normal for accuracy to change with wind speed. Higher speeds increase turbulence around the anemometer structure, which can lead to a more variable response and so reduce accuracy.
How much it changes varies by sensor. The WindObserver 65 and WindObserver 70 hold the same stated accuracy across their whole measurement range. The WindSonic 60 and WindSonic 75 are stated in bands, with the figure widening at higher wind speeds. Having the full-range information available is what lets an engineer pick the appropriate product for the application.
Why is accuracy specified as RMSE?
The root mean square error (RMSE) is an averaged parameter which shows how far a device typically reads from an expected value. It incorporates both the bias error and the variance of the instrument over a range of conditions.
Gill calculates RMSE from a full 360° rotation of the anemometer at each wind speed, so the errors reported are a fair reflection of how the device performs through all angles of attack rather than in one orientation.
How was Gill’s full-range accuracy data measured?
The 2026 test programme covered the WindSonic 60, WindSonic 75, WindObserver 65 and WindObserver 70. It was carried out at accredited facilities at the University of Southampton, using a statistically significant sample of each product type, so the resulting accuracy figure reflects the product rather than the behaviour of a single instrument. RMSE is calculated from a full 360° rotation of the anemometer at each wind speed.
Which Gill wind sensors have full-range accuracy data?
Six products: WindSonic 60, WindSonic 75, WindObserver 65, WindObserver 70, MaxiMet and WindUltra. Each one is shown on this page with its published figures, and the same figures appear in the current datasheet and manual for that product.
Can I use full-range accuracy data in a tender or design specification?
Yes. The figures are published in the released datasheets and manuals for each product, which makes them citable in a tender response or design specification. They are derived from accredited testing across multiple units of each product type, so they can be justified if queried.
Why has Gill published full-range accuracy data?
Because customers ask for it and tenders increasingly require it. Instruments are being deployed in more extreme conditions and across a wider geographic spread than when the 12 m/s reference point was set, and full-range accuracy statements are now common across the sector. Publishing the data gives engineers a more complete basis for specification and lets products be assessed against the conditions they will actually encounter.
Specifying an anemometer
What does an anemometer accuracy specification mean?
An anemometer accuracy specification describes how closely the sensor’s reported wind speed and direction correspond to the actual conditions being measured. The way accuracy is stated matters, because a single value at one reference wind speed does not describe performance across the sensor’s complete operating range.
Why is accuracy at 12 m/s commonly quoted for anemometers?
12 m/s is commonly used as a reference condition because it provides a consistent point at which different sensors can be assessed. It also sits above the average wind speed for the UK and Europe and is typical of a moderately strong breeze, so it long described the conditions most instruments encountered. It does not show how measurement performance behaves at other wind speeds, which is why full-range data matters for applications with a wider operating envelope.
How should I specify an anemometer for my application?
Start with the wind speeds the sensor needs to measure, including the lowest and highest credible conditions. Then consider the required accuracy across that range, resolution and starting threshold, environmental conditions, output and communications requirements, power consumption, and any approvals or certifications the application requires.
Is a wider wind-speed range always better?
No. A wider measurement range is only valuable if the application needs it. The sensor should be selected according to the credible operating conditions, the required measurement performance, the environmental requirements and the system specification. Specifying capability the application does not need adds cost without a corresponding benefit.
What is the difference between wind-speed range and accuracy?
Wind-speed range defines the conditions within which the sensor is designed to measure wind. Accuracy describes how closely its measurement represents the actual wind speed. A sensor can have a very wide measurement range without providing the same accuracy at every point within it, which is why both specifications need to be considered together.
Why does low-wind accuracy matter?
Applications such as air-quality monitoring, environmental measurement and some meteorological systems spend significant periods operating at relatively low wind speeds. Resolution and starting threshold become important in these conditions, because the sensor has to detect and report small amounts of air movement reliably.
Which accuracy specification do I need for my application?
That depends on the wind range, the environment and the purpose of the measurement. If accuracy is critical to the application, our team can help establish which sensor and which performance specification are appropriate.
Comparing, installing and finding the data
How do I compare the accuracy of different anemometers?
Compare the accuracy specifications under equivalent conditions and, where the data is available, examine performance across the wind-speed range rather than comparing isolated reference-point figures. Also consider resolution, starting threshold, environmental performance, output, sampling rate and any application-specific approvals.
What is the difference between an ultrasonic and mechanical anemometer?
An ultrasonic anemometer measures wind using ultrasonic signals rather than rotating cups and vanes. This removes mechanical components from the wind measurement process, which reduces mechanical wear and maintenance requirements and allows more compact sensor designs.
Does the environment affect which anemometer I should specify?
Yes. Temperature, icing, corrosion, water ingress, vibration and exposure to severe weather all influence sensor selection. The required environmental protection and construction should be considered alongside measurement performance rather than treated as a separate specification.
Where should an anemometer be installed for accurate measurement?
The sensor should be positioned so that the measured airflow represents the conditions the application is intended to monitor, and is not unduly affected by nearby structures or other sources of flow disturbance. The appropriate installation arrangement depends on the application and the relevant measurement standards.
Where can I find the full-range accuracy data?
The published data is included in the current released datasheets and manuals for each applicable product. Those documents are linked from the product cards on this page, from the individual product pages, and from the datasheet library.
Six products. Six operating ranges.
One clearer picture of performance.
Each card carries the published full-range figures for that product, as they appear in the current datasheet.
WindSonic 60
Proven ultrasonic measurement for general-purpose applications
Low-power, solid-state wind speed and direction measurement to 60 m/s in an ASA/PC blend (LURAN S KR 2861/1C) body, highly resistant to water, rain, humidity and UV, with no moving parts. Specified for general meteorology, building management, solar installations and OEM integration.
WindSonic 75
Extended wind-speed range for exposed installations
The same compact, low-power architecture as the WindSonic 60, with measurement extended to 75 m/s for installations where higher wind speeds form part of the credible operating environment, including bridges, traffic systems and exposed infrastructure.
WindObserver 65
Heated stainless steel measurement for demanding environments
Ultrasonic measurement to 65 m/s in a 316 stainless steel body with integrated heating and output rates to 10 Hz. Lloyd’s Register Type Approved, and specified for marine, offshore, coastal and wind energy installations where exposure and year-round availability drive the requirement.
WindObserver 70
Approved wind measurement for aviation and other critical applications
Heated stainless steel ultrasonic measurement to 70 m/s, accepted by the FAA and CAA for AWOS surface wind reporting and Lloyd’s Register Type Approved. Specified where measurement performance, environmental protection and formal approvals are all part of the same requirement.
MaxiMet
Full-range accuracy across the compact weather station range
Wind measurement alongside temperature, humidity, pressure and other parameters in a single compact station. Wind accuracy has been stated across the operating range for some time, so the same basis for specification already applies.
WindUltra
Compact measurement to 75 m/s for mobile and harsh environments
Compact and lightweight for UAV, USV and other mobile or severely exposed installations. Its accuracy has been stated across the operating range for some time, and it holds the tightest low-speed direction figure of the six products on this page.
Five decisions that shape the specification
Measurement range
Start with the wind speeds the application actually needs to measure. Include credible extremes, not just the conditions the site sees most often. The sensor needs to perform across the range that matters to the application.
Accuracy across the range
Accuracy at one reference speed tells you one point in the sensor’s performance. Where conditions vary, look at how accuracy changes across the operating range, not just the headline figure.
Low-wind performance
Some applications depend on detecting very small changes in air movement. Resolution and starting threshold become important here, particularly where low wind speeds affect the decision being made.
Output and integration
The measurement is only useful if the receiving system can use it. Specify the communications protocol, output rate, power requirements and interfaces alongside the sensor.
Environmental exposure
Temperature, icing, corrosion and water ingress all place different demands on an anemometer. Specify the instrument against the conditions it will actually encounter, including the extremes.
Need help choosing?
The conditions decide the specification
Tell us what you need to measure, where and under what conditions. We’ll help you work out the appropriate approach.
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