How to choose a trapezoidal spirit level: length and accuracy

The trapezoidal spirit level is the choice for those who often work in tight spaces: the aluminium trapezoidal profile is rigid yet easy to handle. In the collection the lengths range from 250 mm to 1 m. For shelves, installations and small assembly jobs 400-600 mm is enough; to align doors and frames you need 800-1,000. Check for a horizontal and a vertical vial, the accuracy and, if you work on iron, the magnetic version.

Types

• FatMax MLH spirit level: the professional aluminium series. Examples: the FatMax MLH 1-42-312 Stanley and the 1-42-315.
• FatMax MLH magnetic spirit level: same structure, with magnets on the base: it sticks to steel beams, pipes and profiles. For example the magnetic 1-42-423.
• G.P. spirit level: the general-purpose version, simpler, suited to occasional jobs. An example is the G.P. 1-42-802.
• Two-base spirit level: it has two milled bearing bases, like the TMLH-3205 (1-42-253) Stanley, and can be rested on several sides.

How to choose for the job

What to look for

• Length (250, 300, 400, 500, 600, 800 and 1,000 mm): the product pages also give it in inches. A long level is more reliable on a large surface, a short one fits into tight spots.
• Accuracy (1 or 2 mm/m): this is the deviation of the centred bubble for every metre. 1 mm/m is more accurate and suits careful assembly work. 2 mm/m is enough for less critical jobs.
• Vials: the collection has a 180-degree (horizontal) and a 90-degree (vertical) vial. No 45- or 360-degree vials are included: if you need them for slopes, go for other levels.
• Magnetism: present only on some models. Useful on iron, irrelevant on wood and masonry.
• Material (aluminium): light and rigid, it does not rust.
• Milled base: the bearing face is machined, so the level sits well and the reading is repeatable. Keep it clean and don't drag it over rough surfaces.
• Fixed end caps: they cannot be removed. They protect the level from drops.
• Handle: no model has one: the level is held by its profile.

Common mistakes

• Taking a level that is too short for frames: over a short length a tilt error goes unnoticed, over a metre you can see it.
• Not checking calibration: rotate the level 180 degrees at the same spot: the reading must stay the same.
• Using it on a dirty base: dust and mortar throw off the reading. Clean the base before resting it.
• Choosing the magnetic one for work only on walls or wood: it isn't needed and it picks up filings.
• Using a single level for everything: the trapezoidal reaches 1 m. For larger surfaces, such as whole walls or screeds, you need a longer level.
• Using it for hammering: a knock shifts the vials and accuracy is lost.

Frequently asked questions

What is the most useful length?

For a single general-purpose tool 600 mm is fine. If you often work with frames and doors, add one of 800-1,000 mm.

What is the difference between 1 mm/m and 2 mm/m?

With 1 mm/m the centred bubble indicates a surface that deviates by at most one millimetre per metre, with 2 mm/m by two. For precision work take the first.

Do I need the magnetic level?

Only if you work on steel: beams, pipes, profiles. The magnet holds the level in place and leaves your hands free.

Can the trapezoidal level replace the box section level?

For assembly, installations and fitting frames, yes. To check walls or floors over long stretches you need a longer level.

What does two-base spirit level mean?

It has two milled bearing bases, so you rest it on several sides depending on where you are working.

You will find all the models in the trapezoidal spirit levels collection: to choose the right length, request a quote or ask the AMES technicians for advice.