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How to Measure Spiral Window Balances

How to Measure Spiral Window Balances

Measuring a spiral window balance correctly is an important first step in finding a compatible replacement. You will need to record the diameter and length of the metal tube, along with the balance tip color and window application.

Spiral balances may look similar while differing in tube diameter, length, tension rating, and whether they are designed for tilt or non-tilt windows. Keep the original balance available until the replacement has been identified and tested.

Before You Start

Remove the spiral balance from the window before measuring it. Measurements taken while the balance is still installed can be difficult to read accurately.

You may need:

  • Tape measure
  • Ruler or caliper
  • Pen and paper
  • Phone or camera for reference photos
  • The original spiral balance

Important: Measure only the metal tube when recording the balance length. Do not include the colored coupling, exposed spiral rod, or other projecting components.

Step 1: Measure the Tube Diameter

Measuring the diameter of a spiral window balance tube

Measure directly across the outside of the metal tube. This measurement identifies the balance diameter.

The two most common tube diameters are:

  • 3/8 inch
  • 5/8 inch

In the window-balance industry, 5/8-inch and 9/16-inch tube measurements may sometimes be used interchangeably. The balance shown in the image is identified as a 5/8-inch balance.

If the measurement is difficult to determine with a tape measure, use a ruler or caliper and take a clear photo of the tube beside the measuring tool.

Step 2: Measure the Metal Tube Length

Measuring the full metal tube length of a spiral window balance
Close-up showing where to stop when measuring a spiral balance tube

Position the tape measure at one end of the metal tube and measure to the opposite end of the tube.

Do not include:

  • The colored coupling or tip
  • The exposed spiral rod
  • Hooks, brackets, shoes, or other attachments
  • Any component extending beyond the metal tube

The example shown has a metal tube length of 14 inches.

Tip: Record the exact measurement rather than estimating or rounding. An incorrect tube length can prevent the balance from fitting or operating correctly.

Step 3: Record the Tip Color

Look at the colored coupling or tip near the end of the balance and record its color. Depending on the balance series, the color may help identify the tension or sash-weight range.

Common colors may include:

  • White
  • Red
  • Blue
  • Green
  • Yellow
  • Black

Important: Tip colors are not necessarily interchangeable across every spiral-balance series. Match the tube diameter, length, window application, balance series, and appropriate sash-weight range before ordering.

If the tip is faded, damaged, missing, or a color you do not recognize, take a clear photo and determine the sash weight when possible.

Step 4: Identify the Window Application

Determine whether the balance came from a tilt or non-tilt window. Spiral balances for these applications can use different components and installation methods even when their tube measurements are similar.

Tilt Window

The sash tilts inward for cleaning or removal. The spiral balance commonly connects to a pivot lock shoe inside the jamb.

Non-Tilt Window

The sash does not tilt inward. The balance may connect to sash clips, carrier hardware, or other non-tilt mounting components.

Spiral Balance Measurement Checklist

Tube

  • Metal tube diameter
  • Metal tube length
  • Exact measurements

Identification

  • Colored tip or coupling
  • Any markings or labels
  • Clear photos

Application

  • Tilt or non-tilt window
  • Original attachment style
  • Sash weight, if needed

Common Measuring Mistakes

  • Including the spiral rod or colored coupling in the length
  • Measuring the circumference instead of the tube diameter
  • Estimating the tube size by appearance
  • Ignoring the tip color or balance series
  • Ordering a tilt balance for a non-tilt window, or vice versa
  • Discarding the original balance before confirming the replacement
  • Choosing a replacement without confirming the sash-weight range

Video Guide

Watch the video below for a visual demonstration of how to measure the tube diameter and metal tube length of a spiral window balance.

Final Takeaway

To measure a spiral window balance, record the diameter and length of the metal tube only. Then note the colored tip, window application, attachment style, and any available markings.

Accurate measurements, clear photos, and the original balance make it much easier to identify a compatible replacement.

Updated on 22 Jul 2026