DIN 3113 is the German national standard for combination wrenches with equal openings, meaning an open end and a box end of the same size on one wrench. Its full title is “Combination wrenches with equal openings, test torque series A and C.” The current edition is dated September 2007 and listed as current by DIN Media. In practice, when a metric combination wrench says “DIN 3113” on the package or spec sheet, it tells you the tool has to survive defined test torques on both ends.
That sounds dry until you are buying for a shop, a fleet or a maintenance contract. This guide explains what the standard covers, how it relates to ISO 7738 and the Form A and Form B patterns, what the label does not tell you, and how to specify wrenches so the replacement you order fits the job and your tool tray.
TL;DR
- DIN 3113 sets test torques for combination wrenches with equal openings: series A on the ring (box) side and series C on the open-end side.
- The standard is German (DIN, the German Institute for Standardization). The wrench shapes you see listed with it, Form A and Form B, line up with ISO 7738.
- Form A is the standard-offset pattern. Form B is the deep-offset pattern, built for reaching recessed bolts.
- The standard does not rate a brand. Steel grade, finish and fit still decide how a wrench performs in your hands.
- If you buy for institutions or contracts, naming the standard in your spec removes ambiguity. Check the exact form and size range before you order.
Table of Contents
- What DIN 3113 actually covers
- DIN 3113 vs. ISO 7738 vs. ISO 3318
- Form A vs. Form B: which one fits your work
- What the DIN 3113 label does not tell you
- Why buyers write DIN standards into contracts
- How this fits with tool control and organized trays
- Our perspective: standards are only useful if the tool stays in your hands
- Where to find metric combination wrenches
- Quick buying guide
- FAQ
- Sources
What DIN 3113 actually covers
DIN stands for Deutsches Institut für Normung, the German Institute for Standardization. It develops standards for industry and society, and its numbered documents are widely referenced in private contracts, procurement and maintenance agreements. That is the reason a German standard shows up in American shop catalogs at all: it gives a buyer a shared, checkable reference.
DIN 3113 is narrow on purpose. According to the Swedish Institute for Standards listing, wrenches built to it must meet the series A test torques on the ring side and the series C test torques on the open end. The document is eight pages long and is a foreign standard, so you buy it from a standards seller rather than reading it free online.
In plain terms:
- Equal openings. Both ends of the wrench fit the same fastener size. A 13 mm combination wrench has a 13 mm box end and a 13 mm open end.
- Test torque, not just dimensions. The standard defines the torque a wrench of each size has to withstand during testing. That is a strength requirement, which is different from a size chart.
- Two series. The ring end and the open end are tested against different torque series (A and C), because a box end surrounds the fastener and an open end grips only two flats. The open end is the weaker design, so it is tested to a different series.
The standard is also not the same as a performance guarantee. It is a floor that a manufacturer certifies against. What happens above that floor is down to the steel, the forging, the heat treatment and the finish.
DIN 3113 vs. ISO 7738 vs. ISO 3318
This is the part that confuses most buyers, because product pages stack three numbers together. A typical listing reads something like “DIN 3113, ISO 3318, ISO 7738.” One retailer’s listing for a Form B wrench cites all three at once.
A workable way to read them:
| Number | What it is generally used for |
|---|---|
| DIN 3113 | Test torques for combination wrenches with equal openings (series A and C) |
| ISO 3318 | The international torque-related reference that DIN 3113 listings commonly pair with |
| ISO 7738 | The shape and form reference, where you find Form A and Form B |
One specialist knowledge-base article makes the same split: DIN 3113 addresses torque and delivery, while the physical design often aligns with ISO 7738 forms. We treat that as a useful rule of thumb, not a legal definition. If a contract hinges on it, read the standard text itself.
Form A vs. Form B: which one fits your work
The form letter is the practical detail that affects how a wrench feels and where it reaches.
Form A is the standard-offset pattern. The article cited above describes the standard offset as having the open end angled roughly 15° from the handle axis, with a box end that clears adjacent obstructions and gives your fingers some room. Form A is what most general-purpose combination wrenches look like, and it is the geometry familiar to many US technicians.
Form B is the deep-offset pattern. The box end sits farther from the handle line, so it reaches into recessed spaces. The same source says it is intended for recessed bolts in engine bays and tight industrial machinery. A Form B wrench is a good pick when the fastener sits at the bottom of a pocket and a flat handle would hit the casting first.
Here is how that plays out:
- Bolts on a flat surface. Form A is enough, and it is usually the lower-profile choice.
- Bolts in a recess, behind a bracket or inside a bellhousing. Form B gives the clearance.
- Mixed duty. Many techs carry Form A as the main set and add a few Form B sizes in the sizes they use most in the engine bay, typically 10 mm through 19 mm.
Market listings note the open-end jaw angle too. One industrial supplier lists a Form B wrench with a 15° jaw angle and a ring side that is flat with a depressed centre, though you should confirm against the specific product’s data sheet.
What the DIN 3113 label does not tell you
A standard number is a starting point for a spec, not a replacement for one. Here is what you still have to check.
Steel and finish
The standard sets test torque. It does not say which alloy to use. Many DIN 3113 wrenches are made from chrome vanadium steel, and manufacturers describe it that way in their listings, but the grade, forging quality and heat treatment vary between brands. Look for the steel named on the product page, not just the standard.
Box-end profile
Twelve-point (double hex) ring ends are common on combination wrenches, and some makers add proprietary profiles to grip the flats instead of the corners. The standard does not dictate the profile, so two wrenches can both claim DIN 3113 and behave differently on a rounded fastener.
Size range and units
DIN 3113 is a metric standard. Inch-size wrenches sometimes carry the form designation “similar to” the standard, which signals a design match rather than a certified metric size. Read that wording closely when you are buying for a contract that cites the standard by name.
Edition date
The 2007-09 edition is the one listed as current. If a procurement document references an older edition, ask which one the buyer actually wants. Standards bodies can revise or withdraw documents, so check the DIN Media listing before you write the standard into a purchase order.
Why buyers write DIN standards into contracts
Standards compliance works like insurance against ambiguity. When a facility or agency asks for “DIN 3113 combination wrenches,” anyone can check a tool against a published document. It narrows the room for disputes about whether a tool was fit for the task, and it gives a purchasing officer something concrete to reference. The DIN overview in the standards reference notes this role for standards in contracts and procurement.
If you manage maintenance for a plant or a fleet, here is a short checklist for a wrench specification:
- Name the standard and the edition (for example DIN 3113:2007-09).
- Name the form (A or B) so the geometry is not left to the supplier.
- State the size range and the unit system (metric or inch).
- State the material and finish you expect.
- Ask for a warranty in writing.
If you also need torque-controlled work, such as torque wrench calibration or fastener torque specs, the combination wrench standard will not cover it. A combination wrench test torque is about the wrench surviving the load, not about tightening a bolt to a number.
How this fits with tool control and organized trays
Form matters more than most people expect once your wrenches live in foam. A Form B wrench has a deeper offset than a Form A wrench of the same size, so the cutout shape differs. If you replace a lost 17 mm with a different form, it may not sit in the slot cut for the original. That is a small thing until a shadowed slot stays empty on a shift check and nobody can tell whether the tool is missing or just the wrong shape.
A few habits that help:
- Standardize on one form per set and note it on the tray label.
- When you replace a tool, order the same form and the same length series.
- Keep spare slots for the Form B sizes you use only occasionally.
If you carry other hand tools from European-standard makers, the same discipline applies to the rest of the kit. Screwdrivers, for example, are specified against their own norms, and a Swedish retailer lists a range of screwdrivers with quick delivery if you want to compare how they present specs and stock.
Our perspective: standards are only useful if the tool stays in your hands
We design Teng Tools in Sweden, and we have done so since 1985. Our range covers more than 3,000 tools built to ISO and DIN standards, from sockets and ratchets to wrenches, pliers and screwdrivers. We have written more about that approach in our piece on ISO and DIN hand tools for professional work.
Here is how we think about DIN 3113 as a standard:
It is a floor, not a finish line. A test torque tells you a wrench will not fail in a defined test. It does not tell you how the wrench feels at the end of a ten-hour day. That is why we pair standards with a lifetime warranty. If a tool fails, you should not have to argue about it.
Specs help most when the tool has a home. The most common complaint we hear from mechanics is a missing tool, not a broken one. Our Get Organized™ system gives every tool a place in a tray, so a quick look tells you what is gone. A standard tells you the wrench is right. A tray tells you the wrench is there.
Buy for the job, not the label. Form A for general access, Form B where the fastener sits in a pocket. Check the form, check the size range, and keep the set together.
For institutional buyers, we also offer TAA-approved options, and we ship from our Fort Worth, Texas warehouse the same day on orders.
— David
Where to find metric combination wrenches
If you need individual metric sizes to fill gaps in a set, we list single combination wrenches by size, for example the 11 mm, 13 mm, 24 mm and 27 mm metric combination wrenches, plus larger sizes up to 36 mm.
If you would rather start with a complete, organized kit, browse our tool kits and mechanics tool sets. Our foam tool sets in pre-cut EVA trays keep each wrench in its own outline, and our Mecca Pro Series starts from $189 if you want a step up in storage. Check each product page for the specific wrench details before you order.
Quick buying guide
| If you need… | Look for… |
|---|---|
| General-purpose metric wrenches | Form A (standard offset), metric sizes, named steel grade |
| Access into recessed bolts | Form B (deep offset), the sizes you actually use |
| Contract or institutional supply | Standard and edition named in the spec, written warranty |
| Tools that stay organized | A tray or foam layout that matches the form and size |
| Replacement for a lost wrench | The same form, size and length series as the original |
FAQ
What does DIN 3113 stand for?
DIN is the German Institute for Standardization, and 3113 is the number of the standard. The document covers combination wrenches with equal openings and sets test torques for the ring side (series A) and the open end (series C). The current edition is dated September 2007.
Is DIN 3113 the same as ISO 7738?
No. Product listings often cite them together, but they cover different things. DIN 3113 deals with test torques, while the form of the wrench, such as Form A or Form B, lines up with ISO 7738. If a spec depends on the difference, read the standards themselves.
What is the difference between Form A and Form B?
Form A is the standard-offset pattern, common for general work. Form B is the deep-offset pattern, intended for reaching recessed fasteners such as those in engine bays or tight machinery. Choose by where your bolts sit, and keep each form in its own tray slot.
Are DIN 3113 wrenches metric only?
The standard is written around metric widths across flats. Some inch-size wrenches are described as similar to it, which is a design match and not a metric certification. If you buy under a contract that names DIN 3113, confirm the sizes are metric.
Sources
- DIN 3113, 2007-09 listing at DIN Media
- DIN 3113 listing at the Swedish Institute for Standards
- Specifying German Metric Hand Tools for Maintenance Work, Industrial Monitor Direct
- Fasteners 6, What are DIN Standards?
- Combination Wrench DIN 3113, Form B, product listing at Tools Giant