Securing Your Cargo: The Ultimate Guide to Container Locks
A shipping container has heavy steel doors, but a thief will look for the easiest way through. A shipping container lock that fits snugly inside the lock box gives them less room to attack the padlock.
So how do you find one that fits? This guide shows you what to measure before ordering, then helps you weigh up CEN security grades against price. If you’re buying locks for multiple containers, it also explains your keying options.
Estimated reading time: 8 minutes
Contents
- How Shipping Container Locks Work
- Shipping Container Lock Size and Fit
- CEN Security Grades Compared
- Best Padlock for Shipping Container Use
- How to Secure a Shipping Container
- Key Management for Trade and Fleet Use
- Maintenance and Inspection
- Buying Container Padlocks in Bulk
- Frequently Asked Questions
How Shipping Container Locks Work
Most shipping containers use locking rods to hold the doors closed on both the left and right hand side. If you use a padlock on the locking bars only this will prevent them from being opened but will also be prone to attack as the padlock is completely exposed to attack.
If the shipping container has a centrally mounted lock box, this is the preferred method of securing the container by using a container style padlock within the lockbox. It hides most of the padlock body from cutting and leverage tools. The trade-off is a tighter working space. You can only use a select range of padlocks that are suitable to fit within and underneath the lockbox. A traditional U shaped padlock will not work and it will have to be a slidebolt style padlock with a straight shackle.
Slide-bolt container padlocks replace the usual U-shaped shackle with a straight locking bolt. They are also described as block or monoblock padlocks. Some retailers use the term straight-shackle padlock. Their low-profile shape suits many lock boxes and reduces exposed metal. A fully shrouded storage container padlock follows the same principle by keeping the locking section close to the body.
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Even a strong padlock is held back by weak metalwork or poor welds.
”The fitting deserves the same attention as the lock. Even a strong padlock is held back by weak metalwork or poor welds. Inspect the lock box first, then make sure the door handles and rods sit firmly in place.
Shipping Container Lock Size and Fit
An 80mm padlock sounds like it should fit an 80mm space. In practice, the body can catch on the side of the lock box, or you might get it in place only to find there’s no room to turn the key.
Measure the internal width and depth of the lock box, then check the diameter of the locking hole. Try the measurements with the container doors fully closed. Doors can sit slightly differently on uneven ground, and the lock needs to work in the position you’ll actually use it.
Once you know what fits, consider:
Security grade: if your insurer or customer contract specifies a CEN grade or approved lock type, use that as your starting point.
Weather exposure: choose a lock suited to outdoor use, and check how to keep its mechanism working smoothly.
Key access: think about who needs a key. Restricted keys give you more control over copies.
Replacements: using the same lock model or key system across several containers can make a damaged lock easier to replace.
⚠️
Check your insurance wording before you order.
Requirements can cover the lock itself, how it’s fitted and whether the container may be left unattended.
CEN Security Grades Compared
Terms such as heavy duty are difficult to compare on their own. A CEN grade gives buyers a tested reference point. BS EN 12320:2021 sets out the requirements for mechanical padlocks and their fittings. Its security scale runs from Grade 1 to Grade 6, with Grade 6 offering the highest tested attack resistance. Corrosion resistance is graded separately, so the security number isn't a weather rating.
The table puts each grade into a practical container-buying context. The fitting and insurance wording still decide what is suitable for a particular site.
| CEN grade | Security level | Typical use | Guidance for containers |
|---|---|---|---|
| 1 | Low | Lockers and low-value indoor storage | Below the level normally considered for cargo or site storage |
| 2 | Standard | Toolboxes and lower-risk general use | Usually too light for an exposed shipping container |
| 3 | Medium to high | Sheds and lower-risk commercial stores | Consider only where the contents and policy allow it |
| 4 | High | Commercial storage holding higher-value equipment | A useful benchmark for many trade container applications |
| 5 | Extra high | High-value commercial assets and exposed sites | Suits higher-risk use if the lock fits the container hardware |
| 6 | Maximum | Critical assets and locations with a high theft risk | The strongest grade, but larger cost and dimensions must be justified |
CEN grade
1
Security level
Low
Typical use
Guidance for containers
Below the level normally considered for cargo or site storage
CEN grade
2
Security level
Standard
Typical use
Toolboxes and lower-risk general use
Guidance for containers
Usually too light for an exposed shipping container
CEN grade
3
Security level
Medium to high
Typical use
Guidance for containers
Consider only where the contents and policy allow it
CEN grade
4
Security level
High
Typical use
Commercial storage holding higher-value equipment
Guidance for containers
A useful benchmark for many trade container applications
CEN grade
5
Security level
Extra high
Typical use
High-value commercial assets and exposed sites
Guidance for containers
Suits higher-risk use if the lock fits the container hardware
CEN grade
6
Security level
Maximum
Typical use
Critical assets and locations with a high theft risk
Guidance for containers
The strongest grade, but larger cost and dimensions must be justified
A higher grade can't compensate for weak door hardware. Aim for a similar security level across the padlock and fitting, then check that the finished setup meets the insurer's definition of an approved lock.
Best Padlock for Shipping Container Use
The best padlock for shipping container use is first and foremost one that fits. Security grade and keying choice should then reflect how the site operates. This comparison uses specifications and starting prices shown by Locks Direct in September 2026.
| Model | Stated rating | Main construction | Starting price ex VAT | Best suited to |
|---|---|---|---|---|
| Squire ASWL2 container padlock | Security rating 7/10; no CEN grade listed | 80mm armoured steel body with an 11mm hardened rotating shackle | £35.35 | A shrouded, lower-cost option where a CEN grade is not specified |
| ABUS 92/65 container padlock | Security rating 7/10; no CEN grade listed | 67mm brass body with steel casing and a hardened steel bolt | £37.91 | Lock boxes with limited internal space |
| Squire WS75 container padlock | CEN Grade 4; security rating 9/10 | 80mm hardened steel body with a 12mm boron-alloy steel shackle | £45.00 | Buyers who need a stated CEN grade and stronger attack resistance |
| ABUS 92/80 container padlock | Security rating 8/10; no CEN grade listed | 80mm brass body with steel casing and a hardened steel bolt | £47.42 | A larger lock box where drill resistance and keyed-alike supply matter |
Stated rating
Security rating 7/10; no CEN grade listed
Main construction
80mm armoured steel body with an 11mm hardened rotating shackle
Starting price ex VAT
£35.35
Best suited to
A shrouded, lower-cost option where a CEN grade is not specified
Stated rating
Security rating 7/10; no CEN grade listed
Main construction
67mm brass body with steel casing and a hardened steel bolt
Starting price ex VAT
£37.91
Best suited to
Lock boxes with limited internal space
Stated rating
CEN Grade 4; security rating 9/10
Main construction
80mm hardened steel body with a 12mm boron-alloy steel shackle
Starting price ex VAT
£45.00
Best suited to
Buyers who need a stated CEN grade and stronger attack resistance
Stated rating
Security rating 8/10; no CEN grade listed
Main construction
80mm brass body with steel casing and a hardened steel bolt
Starting price ex VAT
£47.42
Best suited to
A larger lock box where drill resistance and keyed-alike supply matter
Browse the full shipping container padlock range to compare dimensions and keying options. For requirements above Grade 4, check the CEN-grade padlock range, then confirm that the chosen design fits the lock box or hasp.
How to Secure a Shipping Container
A padlock should slide into place without being forced. Close and align both doors before fitting it. If the bolt catches, check the door position instead of pushing harder and placing strain on the mechanism.
Use this process for a standard lock-box setup:
1
Inspect the locking rods, handles, welds and lock box for damage or movement.
2
Check that the lock body fits fully inside the box and that the bolt passes cleanly through the locking point.
3
Lock the padlock and pull firmly on the body to confirm that it has engaged.
4
Test the door handles without forcing them and record who holds each key.
If the container has no lock box, use a purpose-made fitting that protects the locking point. The hasps and staples range includes options for creating a padlock point, but installation quality matters as much as the hardware. Welding or structural alterations should be completed by a competent installer and checked against the container owner's requirements.
Security seals can show that a container has been opened, but they don't replace a padlock. Treat a seal as a tracking or tamper-evidence measure alongside the physical lock.
Key Management for Trade and Fleet Use
Once several containers share a site, the key system matters almost as much as the unit price. A cheaper set of unrelated locks soon becomes less attractive if staff waste time finding the right key. Uncontrolled duplication adds another cost.
Keyed-alike padlocks allow several locks to open with the same key. They suit one team or a controlled group of containers, although a lost key may affect every lock in that set.
Master-keyed padlocks give each lock its own operating key while a master key opens the full group. Different users can have access to assigned containers without removing supervisor access.
A restricted-key padlock adds tighter control over key duplication. It's useful where authorisation matters as much as physical attack resistance, particularly across depots or sites with staff changes.
Before placing a larger order, decide who needs access and who approves replacement keys. Record the container assigned to each lock. Keep key-holder details in the same register.
Maintenance and Inspection
Container padlocks spend much of their working life exposed to the weather. Inspect the lock whenever the container changes hands and during long-term storage. Corrosion or a stiff cylinder deserves attention, as do fresh marks around the locking point and movement in the fitting.
Clear dirt from the mechanism and use a lubricant recommended for the product. General-purpose oils can attract grit or affect some cylinders, so ensure to use a specialist lock lubricant. Don't force a key that has started to bind.
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Replace the padlock after a confirmed attack.
A distorted body or bolt also calls for replacement. If suitable maintenance doesn't restore smooth key operation, fit a new lock. Replace damaged fittings at the same time rather than returning a new lock to compromised hardware.
Buying Container Padlocks in Bulk
For larger orders, build the specification around standard body sizes and a planned key system. Record the required security grade against the order so procurement teams can compare products on the same basis.
Before requesting a quote, record the number of containers, lock-box dimensions, required CEN grade and preferred key system. Note any sites exposed to salt or heavy contamination because they may need a different finish or maintenance schedule.
Compare any upgrade cost with the value at risk and the insurance conditions. For mixed fleets, order a sample first and test it on each container type before committing to the full quantity.
Browse container padlocks or contact the Locks Direct team with the container measurements and keying requirement. Include the quantity needed for a trade quote.
Frequently Asked Questions
What size shipping container lock fits a lock box?
There’s no universal size. Measure the lock-box opening, internal clearance and locking-hole diameter before ordering. Many standard lock boxes accept slide-bolt padlocks with bodies around 65mm to 80mm, but key access and bolt position also need checking.
What is the best way to lock a shipping container?
Use a suitable high-security padlock inside a sound lock box, then check that the door hardware, locking rods and welds are secure. The lock should fit cleanly without being forced into position.
What CEN grade should a shipping container padlock have?
Use the grade required by the insurer or contract. CEN Grade 4 is a useful high-security benchmark for many commercial containers, while Grades 5 and 6 may suit higher-risk assets. The lock still needs to fit the container hardware correctly.
Why use a container padlock instead of a regular padlock?
Container padlocks are designed to fit within the restricted space of a lock box. Slide-bolt and shrouded designs also reduce the amount of exposed metal available to cutting and leverage tools.
Are shipping container padlocks weatherproof?
Many are designed for outdoor use, but resistance to rain, salt and dirt varies between models. Check the materials and protective finish, then follow the manufacturer’s maintenance guidance. Exposed or coastal sites may require more frequent inspection.
Are keyed-alike locks suitable for several containers?
Yes. Keyed-alike locks allow several containers to be opened with the same key, which can simplify access across a site. Where tighter access control is needed, master-keyed or restricted-key systems may be more suitable.
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