You measured your dog carefully. Their neck fits a size S, but their chest matches a size M. Which measurement should come first?
There is no answer that works for every harness. The shape of the model, its adjustment ranges and the manufacturer’s instructions should guide your choice.
First check where you measured
The neck measurement asked for a harness is not necessarily the same as for a collar. Likewise, the chest measuring point must match the diagram for the chosen model.
Measure again with your dog standing. Note the figures in centimetres and check that you have not added a margin the manufacturer already allows for.
If two measurements give very different results, start again before choosing a size.
Look for a size that fits all the required measurements
Look at the full adjustment ranges, not just the letters S, M or L.
For example, if a size fits the chest but its smallest opening is still too big at the neck, it is not automatically suitable. Conversely, choosing the smaller size solves nothing if it cannot properly fit the ribcage.
Weight and breed can give some context, but they do not replace measurements.
Should you always size up?
No. Even with a single manufacturer, the recommendation can vary by model: Ruffwear advises sizing up for its Front Range and sizing down for some configurations of its Web Master. So check the exact product page for the harness.
Source: Front Range guide
Source: Web Master guide
For a puppy, buying far too big “for later” does not guarantee a good fit today.
What to send the seller if in doubt?
Send the measurements, the name of the model you are considering and, if it helps, a photo of your dog standing in profile. Say whether they are still growing and which measurement is causing the problem.
If no size properly covers the required dimensions, another cut or a model with more adjustment may sometimes be better.
Before personalising a patch, also check the size exchange conditions: it is better to settle any doubt before ordering.
Read next
- How to measure your dog for a harness without a tape measure?: to take the measurements again step by step.