The quick answer

Use a flexible tape measure to record the widest part of your dog’s chest and the lower part of the neck where the harness will sit. Compare both measurements with the exact product size chart rather than choosing a size from breed or weight alone.

A correctly fitted harness starts before the parcel arrives.

Dogs of the same breed can have very different proportions, so choosing a size simply because another Cocker Spaniel or French Bulldog wears it can lead to the wrong fit.

You need a soft tape measure, your dog and a few treats.

Step 1: Help your dog stand naturally

Ask your dog to stand on a flat surface.

Do not measure while your dog is sitting, curled up or stretching. Their body shape changes in these positions, which can affect the result.

Keep the experience calm. Allow your dog to inspect the tape and reward them for standing still.

Step 2: Measure the chest

Wrap the tape around the widest part of your dog’s chest. This is normally positioned behind the front legs.

The tape should follow the body without squeezing the coat or hanging loosely. Record the measurement in centimetres.

Chest girth is one of the most important measurements when selecting a harness, although the exact measurements required can differ between products.

Step 3: Measure the neck

Measure around the lower part of the neck where the harness neckline is expected to sit.

This is often lower than the position of a standard collar. Do not pull the tape tightly.

Record this measurement separately from the chest measurement.

Step 4: Compare the numbers with the product

Open the complete Pawda London size guide and compare both measurements.

Do not assume that a small size in one brand will be identical to a small size from another. Harness shapes, adjustment ranges and sizing systems can vary.

Also check the individual product description because not every collection will necessarily use identical measurements.

Step 5: Check the harness when it arrives

Once the harness is on your dog:

• Check that the straps sit flat.
• Make sure no strap is twisted.
• Confirm that it does not cut into the armpits.
• Check that your dog’s shoulders can move freely.
• Make sure the neckline does not press against the throat.
• Check that your dog cannot easily reverse out of it.

A commonly used fit check is that you should be able to place approximately two fingers beneath the straps without the harness hanging loosely.

What if my dog falls between two sizes?

First, look at the complete adjustment range.

If one size places your dog at the absolute edge of its adjustment, the alternative may offer a more useful range. However, the larger size should not be chosen if it creates gaps or makes escape possible.

Contact the retailer with:

• Neck measurement.
• Chest measurement.
• Breed or body type.
• Current weight.
• A clear side-on photograph.

Do not rely on weight alone.

Common measuring mistakes

Measuring over thick clothing

Measure the dog, not a coat or jumper, unless the harness will always be worn over that garment.

Pulling the tape too tightly

The aim is to record the body measurement, not compress the coat and skin.

Using an old measurement

Puppies grow, adult dogs change weight and coats become thicker or shorter. Measure again before replacing equipment.

Guessing from breed

Breed can provide context, but it cannot replace the measurements.

Frequently asked questions

Can I use string instead of a tape measure?

Yes. Wrap a non-stretch piece of string around the correct area, mark where it meets and then measure the string against a ruler.

How often should I check the fit?

Check regularly, particularly for puppies, growing dogs and dogs whose weight or coat changes.

What should I do if the harness rubs?

Stop using it and check the sizing, adjustment and positioning. Persistent rubbing should not be ignored.

The final check

Your dog should be able to stand, sit and walk naturally. A stylish harness only works when the fit underneath the design is right.