Top 5 Most Secure Padlocks for All Uses – [Ultimate 2024 Guide]

Last updated Feb 15, 2024

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When choosing the best high-security padlock, there are certain brands and features that stand above the rest. Believe it or not, one of the most well-known brands, Master Lock, does not manufacture the most secure padlocks. There are more than enough horror stories written by people who had a Master Lock broken. Needless to say, most of these same people have switched to brands you’ll find in this guide.

Why choose a high-security padlock over a basic padlock? While the answer to this question may seem obvious, let’s go over a few scenarios where a high-security padlock is necessary:

  • As part of a high-security locking system for all types of doors, gates, and halls
  • When storing valuables in a storage container, storage unit, PODS, personal shed, trucks, and even inside your home
  • For securing valuable items outdoors that you often use during the summer months
  • Automotive uses: locking motorcycles, bicycles, motor scooters, and e-bikes
  • To resist corrosion in areas that are exposed to the elements, e.g. as weatherproof padlocks
  • Enhanced perimeter security

To sum things up, the most secure padlocks provide ultimate security against all types of attacks, they stand the test of time, and they resist the elements when used in areas with snow and other wet conditions. The only time you may want to skip an expensive padlock is when storing items of little value.

Let’s start with an overview of the five locks that lists the most important specs.

The 5 Most Secure Padlocks

Lock Description
#1) ABUS 37/80 Granit Alloy Steel Padlock

  • Material: Hardened Alloy Steel w/ Anti-Corrosion Coating
  • Core: ABUS Plus Disc Cylinder w/ Lighted Key
  • Shackle Diameter: 14mm Shackle (9/16″)
  • Size: 80mm
  • Weight: 2.4 lbs
  • Model: 37/80 KD, 37RK/80, 37RK/80 SZP
  • Price: $
#2) Medeco3 System Series Padlock

  • Material: Boron Alloy Steel
  • Core: Elevating and Rotating Tumbler Pin System
  • Shackle Diameter: 5/16″ or 7/16″
  • Size: 2.39″ x 1.33″ x 3.76″ (WxDxH)
  • Weight: 2 lbs
  • Model: 54T52500
  • Price: $$
#3) MUL-T-LOCK MT5+ TR 100 Round “Hockey Puck” Padlock

  • Material: Hardened Steel w/ Nickel Chrome Matte Finish
  • Core: High-Precision Pin Tumbler System
  • Shackle Diameter: .401″
  • Size: 2.913″ Diameter, 1.295″ Depth (Drawing)
  • Weight: 2.05 lbs
  • Model: KW-TR100-MT5
  • Price: $$$
#4) ABUS 37/55 Granit Alloy Steel Padlock

  • Material: Hardened Alloy Steel w/ Anti-Corrosion Coating
  • Core: ABUS Plus Disc Cylinder
  • Shackle Diameter: 7/16″
  • Size: 62.5mm
  • Weight: 1.12 lbs
  • Model: 37/55 (Part Number 37956)
  • Price: $
#5) Sargent & Greenleaf 951C High Security Padlock

  • Material: Cast Stainless Steel Body, Ceramic Inserts, Hardened Steel Pins
  • Core: High-Security Medeco Key Cylinder
  • Shackle Diameter: 12mm
  • Size: 2.75″ x 1.81″ x 4.65″ (WxDxH)
  • Weight: 4.5 lbs
  • Model: 951-009
  • Price: $$$$

Most Secure Padlock Reviews

The highest security padlocks sport a shroud that covers the shackle. However, a shroud does come with it pros and cons. The main advantage is that a shroud makes the shackle inaccessible until it’s cut or removed. The drawback is the shroud can sometimes get in the way depending on how you plan to use the lock.

For this reason, it’s always important to measure twice before you buy a lock to compare how much space you need to the lock’s shackle clearance. One common problem people run into is discovering the lock doesn’t fit after purchase. In the chart above, you’ll find the shackle diameter of each lock and dimensions.

Next, before we start the reviews, always remember that your lock depends on the other components in your locking system, particularly your hasp or chain. Your hasp is the part of the system your lock attaches to that provides a hole for the shackle to pass through. Always be sure your lock will pass through the hole in your hasp before you buy the lock.

Now, let’s go over the reviews of each lock with some pros & cons to consider for each.

#1) ABUS 37/80 Granit Alloy Steel Padlock

When it comes to ultimate security, ABUS Granit locks got you covered from every angle. Additionally, of the locks in this guide, the 37/80 is the best high-security padlock for the money. First, let’s talk about how beefy this lock truly is. With a 9/16″ shackle and 80mm body, this lock is a force of nature. However, it’s extra important to be sure it’s compatible with your planned use(s) before you buy since a 9/16″ shackle is not universal.

One really cool feature is the removable shackle design that makes this lock very easy to use. Also, if a thieve manages to get past the shroud, he or she must make two cuts to remove the shackle from the body. This is different from standard padlocks that feature a swinging shackle that requires just one cut to break.

Another key highlight is the country of manufacture. Unlike cheap padlocks manufactured in China, the ABUS Granit is 100% designed and made in Germany. It carries a CEN (European Committee for Standardization) Class 5 certification, which is considered “Extra High Security” and is just one point away from Grade 6 Maximum Security. On ABUS’ security scale, the 37/80 score is a perfect 10/10. All in all, if this lock size matches your needs, you really can’t go wrong.


  • Weatherproof outer coating to stand up in all conditions
  • Butter-smooth operation
  • Includes 2 keys (1 w/ LED light for clear vision at night) and ABUS’ unique serial number key card for making duplicate keys
  • OSHA-approved for construction purposes in the US
  • Ultimate protection against picking attacks with the ABUS Plus disc cylinder
  • Rekeyable
  • Removable shackle for enhanced protection and easier use
  • An excellent choice for securing motorcycle chain locks or any heavy-duty chain


  • Too large for most public storage units (our list of best padlocks for storage units is a better resource)
  • Not compatible with U-Haul or Penske moving trucks
  • One of the heaviest locks in this guide at 2.4 lbs

#2) Medeco3 System Series Padlock

Medeco Assa Abloy locks are right up there with ABUS, and the System Series is another beefy lock option. The advantage of choosing this lock over the Granit 37/80 is its smaller shackle size. You’ll find that this lock fits most applications with its 5/16″ shackle. Also, if you desire a larger shackle, the same lock is available with a 7/16″ shackle.

The boron alloy steel used to construct this lock makes it a good choice for outdoor applications. Plus, it enhances security by beefing up the tensile strength to protect against pulling and cutting attacks. Like ABUS, you get superior protection against pick attacks with this lock. The Medeco3 pin tumbler system implements a triple locking action to ensure that only the most seasoned lockpickers have a chance.

Additional highlights of the Medeco cylinder include hardened steel inserts for protection against drilling, machined brass components for a lifetime of use, and the option to key your locks alike. Lastly, you get the peace of mind of knowing no one can duplicate your keys in case you lose one with Medeco’s key program in place.


  • The smaller shackle size offers a wider compatibility range than ABUS’ 37/80
  • Protection against unauthorized duplication of keys
  • Weatherproof
  • The Medeco3 pin tumbler system makes this lock mighty difficult to pick
  • The option to key alike if you plan to use multiple locks
  • Boron alloy steel shackle


  • A tight fit on common moving trucks and PODS
  • No lighted key included

#3) MUL-T-LOCK MT5+ TR 100 Round “Hockey Puck” Padlock

Now for one of my favorite padlocks, the “Hockey Puck.” Its unique design makes it one of the best locks for trailer doors because it’s virtually impossible to access the shackle. When paired with Mult-T-Lock’s shock-resistant hasp, you’re looking at a level of anti-theft protection that most thieves will have no chance against. In addition to the high-security design, the MT5+ platform is the real deal.

The MT5+ mechanical platform features a triple-locking mechanism for superior protection against picking, drilling, and bumping attacks. Overall, the Mul-T-Lock key system is similar to what Medeco and ABUS offer. Each Hockey Puck comes with a unique key code ID card to ensure no unauthorized duplication of your keys.

One final tip before choosing this lock is to ensure it’s compatible with your application. You’ll most likely want to purchase a compatible hasp separately for the most secure fit. Currently, Mul-T-Lock offers its own hasp, and there’s a solid steel Master Lock hasp that fits this lock quite nicely.


  • The completely hidden shackle design
  • The premium MT5+ cylinder is extremely difficult to pick
  • Superior compared to cheaper hockey puck style locks
  • The addition of the interacting spring at the tip of the key called the “Alpha Spring” in MT5+ models
  • Each lock includes a duplication card with the option to key multiple locks alike
  • Drill-resistant cylinder


  • You may need to purchase a hasp
  • Limited uses compared to traditional padlocks

#4) ABUS 37/55 Granit Alloy Steel Padlock

If you have your heart set on an ABUS Granit lock, but the 37/80 doesn’t match your needs, the 37/55 model is a good solution. The narrower shackle diameter of 7/16″ and added shackle clearance & height make this lock great for storage units, trailers, and moving trucks. In addition to this benefit, you still get the tough weather-resistant coating and premium ABUS anti-theft features.

Like the 37/80, the 37/55 also scores a perfect 10/10 on ABUS’ security level scale. For protection against manipulation and picking, the 37/55 comes standard with an ABUS-Plus disc cylinder. The hardened alloy steel body can take a beating without losing smooth functionality if you plan to use it for automotive purposes. Additionally, this lock is A-OK for use in the harshest weather conditions.

One final advantage is the price. Of all the locks in this guide, ABUS Granit locks give you the most bang for your buck. Yes, there are locks that cost a lot more – such as the next lock – but for most people who desire a good high-security padlock, ABUS Granit gets the job done and more.


  • You’re less likely to run into clearance issues with this lock than the 37/80
  • Currently the most affordable lock in this guide
  • ABUS-Plus core
  • Corrosion-resistant outer coating for use in all weather conditions
  • ABUS 10/10 security score
  • Protection against unauthorized duplicate keys


  • No shroud or shield
  • Not as beefy as the 37/80

#5) Sargent & Greenleaf 951-009 951C High Security Padlock

Last up is the S&G 951C which is perhaps the most secure padlock in the world and certainly the most secure lock in this guide. For this reason, it costs the most and makes the price of ABUS Granit locks very appealing. If you’re okay with the price, the 951C is a true military-grade padlock that offers the most premium anti-theft protection you’ll find in a padlock outside of the steel chain and fastening plate that comes with it.

The first feature to consider is just how beefy this lock is. The only lock in this guide with a thicker shackle is the ABUS 37/80, yet this lock weighs two pounds more. When you hold it, you’ll instantly feel how substantial it is. As for the core, it’s interchangeable and comes standard with a Medeco core. For the price, the standard core could probably be upgraded, but it is Medeco quality, which is top of the line.

Outside of the cylinder, the lock body is what really sets this bad boy apart from other high-security padlocks. There are ceramic inserts and an anti-drill shield for the highest level of protection against drill attacks. The fully-shrouded shackle makes the lock nearly impervious to physical attacks. Lastly, to give you an idea of how special this lock truly is, it’s built to resist prolonged liquid nitrogen attacks.


  • Interchangeable core for easy cylinder upgrades
  • The most secure lock body you’ll find
  • The highest level of resistance against drilling attacks offered by a padlock
  • A high-security shroud almost completely conceals the 12mm shackle
  • Ideal for reliable perimeter security
  • Military-grade design to meet US military specification MIL-DTL-43607J


  • The most expensive lock in this guide
  • The standard cylinder could be better for the price

Bottom Line

When choosing the most secure padlock, it’s very important to first consider how you plan to use the lock. The second consideration is the most likely type of attack by a thief. Do you plan to use the lock in an area where a thief would have time to pick the lock? This question is important because there are great locks with extraordinarily tough bodies such as the Kasp 19070X with unextraordinary cores to match.

At the time of this writing, Medeco, ABUS-Plus, and especially the Mul-T-Lock MT5+ cores all offer ultimate resistance against picking. In addition to high-security cores, they also come with anti-drilling & anti-cutting features including anti-drill plates and shrouds. The bottom line is that it’s important to match one of the locks in this guide to your needs before you buy one and always be sure the lock size works for your intended uses.

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