Why Weigh Tapes Aren’t Telling You the Full Story

A real-life case study and why accuracy matters going into spring

Weigh tapes are widely used in the horse world. They’re inexpensive, easy to carry, and feel reassuringly “scientific”. But how accurate are they really — and what happens when they’re wrong?

Recently, I weighed two horses using both a standard equine weigh tape and a calibrated mobile weighbridge. The results highlight why tapes should be treated as a rough guide at best, not a reliable measurement.

The Case Study

🐎 Lola – coloured horse

• Weigh tape: 515 kg

• Weighbridge: 570 kg

That’s a 55 kg difference — more than two full bales of hay.

🐴 Daphne – grey pony

• Weigh tape: 420 kg

• Weighbridge: 429 kg

  
  

A smaller discrepancy, but still 9 kg heavier than estimated.

Why Do Weigh Tapes Get It Wrong?

Weigh tapes estimate weight based on girth circumference, using an average formula that assumes a “typical” horse shape. The problem is… horses are anything but typical.

Accuracy is affected by:

• Breed and build (natives, cobs, warmbloods, ponies)

• Fat distribution (crest, belly, quarters)

• Muscle tone

• Coat thickness

• How tightly or consistently the tape is applied

A horse with a wider barrel or uneven fat distribution can appear significantly lighter on a tape than they actually are — exactly what we saw with Lola.

Why These Differences Matter

A 50+ kg underestimation isn’t just an interesting number — it has real-world consequences.

🥕 Feeding

If you’re feeding based on an underestimated weight, your horse may be receiving more energy than intended, increasing the risk of weight gain and metabolic stress.

💊 Medication & Worming

Dosing is calculated by bodyweight. Underestimating weight risks underdosing, which can reduce effectiveness and contribute to resistance — particularly with wormers.

🚛 Transport

Weight matters when loading trailers and 3.5-tonne lorries. Knowing the true weight of your horse (and not a hopeful estimate) is essential for safety and legality.

Why Accuracy Matters Even More Going into Spring

As we head into spring, horses often:

• Gain weight rapidly

• Experience changes in forage and grazing

• Become more vulnerable to metabolic issues

This is the time of year when small inaccuracies can snowball into big problems. Without accurate baseline data, it’s very easy to miss gradual weight gain until it becomes obvious — and much harder to reverse.

So Should You Ditch the Weigh Tape?

Not necessarily. Weigh tapes can be useful for:

• Very rough trend monitoring

• Situations where no other option is available

But they should never be relied upon for:

• Feeding calculations

• Medication dosing

• Transport planning

• Monitoring horses prone to EMS or laminitis

A calibrated weighbridge provides objective, repeatable data — and when combined with body condition scoring and data tracking, it allows you to spot trends early and manage proactively.

The Take-Home Message

Weigh tapes don’t measure weight — they guess.

And as these case studies show, that guess can be wildly off.

If you care enough to manage your horse’s health, feeding, and welfare properly, accurate measurement matters — especially at this time of year.

Measure properly. Manage better.