Ultimate Tensile Strength Explained: No Jargon, Just Facts

13 Jun 2025

When you’re choosing metal for a job, there’s one thing you need to know before anything else – how strong is it? That’s where ultimate tensile strength (UTS) comes in. It tells you how much force a material can take before it breaks under tension.

Sound technical? Don’t worry – this guide keeps it simple. We’ll walk you through what UTS actually means, how it’s tested, why it matters and how different metals stack up.

Whether you’re building a bracket, a scaffold or a support beam – it pays to know your limits.

Article in brief

Ultimate tensile strength (UTS) is the maximum pulling force a metal can take before it snaps.

It’s measured in MPa, psi or N/mm² and helps guide safe, smart material choices.

UTS differs from yield strength – one marks permanent bend, the other full failure.

Common UTS ranges: mild steel (400–550 MPa), stainless (up to 1200 MPa), aluminium (70–500 MPa).

Essential in construction, aerospace and manufacturing – UTS means knowing your limits before things break.

1

What is ultimate tensile strength?

Ultimate tensile strength is the maximum pulling force a material can handle before snapping. It’s the point just before total failure – when your metal says “that’s enough” and gives in.

It’s measured in:

  • Megapascals (MPa) – commonly used in the UK and Europe.
  • Newtons per square millimeter (N/mm²) – slightly less common, this measurement is numerically equivalent to MPa (1 N/mm² = 1 MPa).
  • Pounds per square inch (psi) – often seen in the US.

UTS is one of the go-to ways to compare how tough a metal is when it’s being stretched or pulled apart. It’s not about how hard it is to dent or bend – it’s about how much tensile stress it can take before giving way.

If you're buying metal for anything that carries weight, spans a distance or sees serious strain, UTS should be on your radar.

2

Tensile strength vs yield strength

These two terms often get lumped together – but they’re not the same.

  • Yield strength is the point where a material starts to bend or deform permanently. Think of it as the “you’ve pushed it too far” moment.
  • Ultimate tensile strength is the maximum point – right before it breaks completely.

Imagine stretching a rubber band. It resists, then stretches permanently (that’s yield), then eventually snaps (that’s UTS). With metal, the same principle applies – just with a lot more force.

Both values are crucial when picking materials for construction, manufacturing or anything safety-critical. You want to know when the metal will start to give – and when it’ll fail altogether.

3

Why UTS matters in metal selection

Ultimate tensile strength isn’t just numbers on a datasheet – it’s key to choosing the right metal for the job. Specifically, it can affect:

  • Design decisions – how thick or reinforced a metal or steel part should be.
  • Material selection – it'll guide the choice of material depending on load conditions.
  • Failure prevention – knowing the UTS helps ensure the structure doesn't unexpectedly snap under stress.

In heavy-duty sectors like:

  • Construction – load-bearing beams, RSJs and supports need high UTS.
  • Aerospace – weight is everything, so materials need the best strength-to-weight ratio.
  • Automotive and manufacturing – parts need to hold up under strain, impact and wear.

But higher strength doesn’t always mean better. For example:

  • Mild steel has moderate tensile strength but is easy to work with and cut.
  • Stainless steel is stronger and corrosion-resistant but harder to machine.
  • Aluminium is lightweight and rust-proof, but has a lower UTS.

The right choice depends on the demands of your job – and UTS helps make that decision easier.

4

How UTS is tested

To measure ultimate tensile strength, you’ve got to stretch the metal until it breaks. Literally.

This is usually done using a Universal Testing Machine (UTM). The metal sample is gripped at both ends and pulled apart at a steady rate until it fractures. The machine records the force and the elongation throughout the test.

Key tools used in the process:

  • Extensometers – measure how much the metal stretches.
  • Strain gauges – record deformation in real time.

The test gives you loads of useful data – how far the metal stretches, where it fails and how much force it takes to snap. It’s standard in metal testing labs and essential for building reliable, safe structures.

5

UTS of common metals

Material: Mild Steel


  • Ultimate Tensile Strength (MPa): 400–550

  • Key Characteristics: Easy to work with, great for general construction

Material: High-Strength Steel


  • Ultimate Tensile Strength (MPa): 800–1000+

  • Key Characteristics: Ideal for heavy-duty, load-bearing applications

Material: Aluminium


  • Ultimate Tensile Strength (MPa): 70–500

  • Key Characteristics: Lightweight, corrosion-resistant, good for transport/cladding

Material: Stainless Steel


  • Ultimate Tensile Strength (MPa): 500–1200

  • Key Characteristics: High strength and corrosion resistance, tougher to cut

Material: Brass


  • Ultimate Tensile Strength (MPa): 250–500

  • Key Characteristics: Decorative, corrosion-resistant, good for fittings

Material: Copper


  • Ultimate Tensile Strength (MPa): ~200

  • Key Characteristics: Soft, conductive, used in electrics and plumbing

6

The formula for ultimate tensile strength

If you want the numbers, here’s how it’s calculated:

UTS = Maximum Load (Force) ÷ Original Cross-Sectional Area


It’s usually written as the symbol σᵤ in engineering documents. But unless you’re running a lab, you’re more likely to just check a metal’s UTS on its datasheet or ask your supplier.

Get high-strength metal from The Metal Store

So, what is ultimate tensile strength? It’s the max pulling force a metal can take before it breaks. Simple as that. Knowing it helps you pick the right material – whether you’re building a balcony, a machine frame or a bracket.

It’s not just about strength. It’s about safety, performance and making sure your project doesn’t snap under pressure.

If you’re looking for the right metals for your next project, The Metal Store is your best bet. From mild steel and aluminium to high-strength stainless and brass, we stock the metals that hold up under pressure – literally.

Need a hand picking the right material for your job? Just give us a shout. We’ll help you choose the best metal based on tensile strength, weight, finish and budget. And don’t forget – we cut to size for free, with free delivery available on thousands of products.

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