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Whether it’s winding pipes, ducts, molding, circular frames, or even guitar fretboards, you can say that measuring the radius of a curve is an essential activity for the projects at home.

You can use a contour gauge to precisely measure the contour of any of your metal, woodworking, and other construction projects. It will help you duplicate curves to create cutouts for wood, vinyl, ceramic, porcelain fixtures, and more.

Read to find out the correct way to measure the radius of a curve of home projects and the curve of guitar fretboards.

You can say that a contour gauge is a must-have tool for the DIY handyperson.

You can also find them when they’re called profile combs or shape duplicators. It has a cross-sectional shape that is ABS plastic pins set tight against each other. The frame keeps them level on a plane. You can use it to duplicate any shape to easily transfer to tile and any surface.

**Method 1: Measure the Radius of a Curve Using a Right Angle Protractor**

First, set your protractor to 90 degrees and place it over the curve.

For example, if you are measuring the curve of a bathtub, place the protractor on the outside of the curve.

Next, take note of the measurement of where the curve touches the ruler.

Now, you’ve just found the radius of the curve!

Check out the Youtube video below to see how this works.

You can also use a right-angle ruler and place it over the curve. If you are measuring the interior curve, place the rule just above it. Take of where the curve touches the ruler.

**Method 2: Measure the Radius of a Curve Using a Contour Gauge**

First, use a contour gauge to copy the shape of the curve.

Place the gauge on the curve and lock down the contour.

Next, trace the shape onto a piece of paper.

Now, you can measure the lengths that will be used to calculate the radius of the curve.

One of the ways is to use a protractor to create a semi-circle with the curve. Measure across the semi-circle (or the diameter of a circle). The half-way measurement will be the radius.

**Method 3: Measure the Radius of a Curve Using a Radius Gauge**

With a radius gauge, this expensive and bow-like tool is will accurately measure curvatures without any needed calculations.

An inside radius gauge is a tool for measuring the inside arc.

And the outside radius gauge is a tool for measuring the outside arc.

Like the contour gauges, these variable arc attachments can help you easily transfer the contour for tracing on paper, wood, and other surfaces as you need. It’s a professional tool that’s nice to have if you find that you’re measuring curves “all the time.”

**How to Measure the Radius of Curve for Guitar Fretboards**

The easy and accurate way is to use a guitar radius gauge to measure the bottom curvature of your fretboard radius. The top curvature also matches as a level for setting the saddle heights for the string. The result is the best playability for all kinds of guitars: electric guitar, acoustic guitar, electric bass.

You can quickly and accurately adjust the bridge saddle because each gauge is shaped to fit under the strings. You can also use it to match the heights of the pickup polepiece to the arch of the string.

**How to Measure the Radius of A Curve for Hot Tub or Bath Tub Buying and Installation**

Having a hot tub in your house makes for a relaxing experience. You can chill in the hot tub after a long day and still have fun on cold nights.

Installing that hot tub in a correctly fitted space is crucial, as an inch difference can make the tub installation incomplete. That can be avoided by knowing how to measure the radius of a curve.

Most tubs come with curved corner shapes to give maximum comfort to the user. The curved corners soothe muscles and help the body relax. The hot water takes calms you and regenerates the energy in the body.

To ensure the correct installation of your hot tub, you need to get the correct measurements. Getting a tub that is too small or too large is a risk. And to get the actual reading of the radius of the curved corner, you can follow a few methods.

**Method 1: Imaginary line intersection**

First, use a right-angle ruler and place it over the corner of the curve.

You can set a protractor to 90 degrees and place it over the curve.

Next, take note of the measurement of where the curve touches the ruler.

Congratulations, you’ve just found the radius of the curve!

Check out how those measurements work in those measurements in the Square part of the diagram in this Youtube video:

Both lines will give you the same measurement.

If you see that you have different readings for both the lines, then move the protractor so that the lines are at a 90-degree angle.

You may need to imagine that line to get the correct reading of the radius.

This way, your measurements will be accurate, and you can buy the right-sized tub for your space.

**Method 2: Paper tracing**

This is one simple method to calculate the radius of a corner. For this, you will need to have a piece of tracing paper or newspaper, and an old cover of the current tub.

Regular paper usually is not large enough, so old newspapers or tracing paper is preferred.

Grab the old tub cover and then place a few newspapers on the floor. If needed, use masking tape to hold the newspapers in place.

Place the cover on top of the newspaper. Align a corner of the cover on top of the edge of the newspaper.

Use a pencil to trace the curved, free space onto the newspaper where the cover is curved. You will now have the radius of the corner of the current tub.

Get a measuring tape to measure your tracing.

**Method 3: Let the pros do it**

You will need tracing paper and a pencil. Place the tracing papers on top of the tub or area and mark them on paper.

Then take it to a bathtub or hot tub store and the professionals will get a radius measurement for your hot tub installation. This will help you replace the old tub quickly.

**How to Find the Radius of a Curve in a Garden Path?**

For large spaces like garden paths, finding the radius of a curve will take a different method. Check out this video for how to lay a circular curve using a string compass.

Whether you’re dealing with pipes, ducts, awkward shapes like the hot tub, or circular frames, you will need to find out the radius of the curve.

Getting accurate measurements can save you time and money. With the correct way to measure the radius, you’ll get to enjoy things that fit without the stress.

Related:

How to Measure a Bathtub

How to Install Baseboard Molding on Uneven Floor – 6 Easy Steps