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How to Replace Sofa Cushions with New Foam Inserts

Published 28 August 2025 · Updated 7 July 2026 by
Admin

A Practical Guide to Measuring, Selecting Foam, and Ordering Online

Is your lounge sagging, lumpy, or just not as comfortable as it used to be? Replacing the foam inserts in your sofa cushions is one of the simplest ways to bring your furniture back to life. It’s affordable, customisable, and surprisingly easy with Home Upholsterer’s online foam price calculator.

Whether you’re replacing one cushion or redoing a full set, here’s a step-by-step guide to help you get it right the first time.

1. Measure Your Cushion Covers, Not the Old Foam

Foam shrinks and softens over time, so it’s important to measure the cushion cover rather than the old insert.

Here’s how:

  • Remove the existing foam insert.
  • Zip the cover closed and gently flatten it without stretching.
  • Measure the width and depth from seam to seam.
  • Measure the thickness based on the side panel or seam-to-seam height.

The Foam Calculator includes help prompts as you work through the order. If you are unsure about a measurement or material choice, check our foam FAQs before ordering.

2. Choose the Right Foam for Your Cushions

We offer a wide range of Australian made open-cell polyurethane foams, each with different firmness levels and best-use applications. Below is a simplified breakdown of the grades we recommend most often for sofa and lounge cushions.

Recommended Foam Grades

Foam Grade Type Density Feel Best Used For
N30-130 Premium 30kg/m³ Medium Everyday sofa seat cushions and backs
N31-190 Premium 31kg/m³ Medium-Firm Sofa arms, firmer seat cushions
H35-200 Heavy Duty 35kg/m³ Firm High-use seating, slim-profile cushions
N23-130 Medium 23kg/m³ Soft-Medium Back cushions, sofa backs, ottomans
DF-FIRM Reticulated 32kg/m³ Firm Outdoor seat cushions, marine use

You can also view our Foam Technical Brochure (PDF) for detailed specifications.

3. Use Our Online Foam Calculator for Instant Pricing

Once you’ve measured your cushion and chosen your foam type, head over to the Foam Calculator to get started.

You’ll be able to:

  • Choose the closest available cushion shape
  • Enter your exact dimensions in millimetres
  • Choose your foam grade
  • Add Dacron wrap if desired
  • Select your intended application from a dropdown list (e.g. sofa seat, backrest, outdoor use)

The application dropdown helps ensure you’re ordering a suitable grade for your project, especially if this is your first DIY cushion replacement.

The calculator displays your price as you build the order, so you can adjust and compare options as needed. All foam is cut to order in our Chester Hill workshop and available for fast delivery or click-and-collect.

4. Why Dacron Wrap Makes a Difference

Dacron is a polyester fibre wrap added to the outside of foam cushions. It rounds the edges, gives the cushion a fuller look and helps the insert slide into the cover more easily. It is a finish layer, not a reason to reduce the foam measurements.

Benefits of adding Dacron:

  • Gives cushions a full, plump look
  • Softens the edges and improves seat feel
  • Helps the foam slide more easily into the fabric cover
  • Reduces friction between the cover and foam, helping prolong fabric life

You can add this option when ordering via the calculator. Our team will professionally wrap it for you before dispatch.

5. Fitting the Foam into Your Covers

Fitting new foam is usually straightforward:

  • Fold the insert slightly (like a taco) and guide it into the cover
  • Take your time around corners and boxed shapes
  • Once zipped, reshape and plump the cushion
  • If it is particularly snug, some silicone spray can be used to help the cushion slide into the covers.

New foam may feel firmer initially but will relax with use. If you selected Dacron wrap, it may feel snug when fitting. That snugness is normal and helps create a smooth, rounded finish once settled.

6. Ready to Upgrade Your Sofa?

Replacing your sofa cushion foam is one of the easiest ways to refresh your furniture without the cost of new upholstery or a brand-new lounge. With Home Upholsterer, you get the confidence of high-quality, Australian made foam, cut to your exact specs, with expert advice if you need it.

Order online, try our instant foam price calculator, or visit us in-store. We’re here to help you get the job done right.

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