# Check a unit for tipping and weight See the weight and the centre of gravity of a unit, find out if it can tip forward, and see where its weight goes. > **AI credit.** Some steps use AI credit. Those are the steps that ask the assistant. You can do the other steps without credit. AI help is pay-as-you-go. No compulsory subscription. Drawing by hand is free for personal use. Prices: https://kerfcraft.app/pricing KerfCraft estimates the weight of each unit and the position of its centre of gravity. For a freestanding unit, it also tests if the unit can tip forward. The check is advice from simple statics and estimated loads. It does not tell you that a unit is safe. ## Show the weight and the centre of gravity 1. Click **⋯** (more view options) above the 3D view. 2. Click **Weight and tipping**. Each unit gets a marker at its centre of gravity. The marker is a circle with two filled quarters. Its label gives the name of the unit, the total weight and the result. A dashed line goes down from the marker to the floor, and a line shows the part of the unit that stands on the floor. The colour shows the result: - **Red**: tipping risk. - **Green**: stays up, or fixed to the wall. - **Amber**: wall-hung. The wall fixings carry all the weight. - **Grey**: built in. The unit is fitted into an alcove or a recess. To remove the markers, click **Weight and tipping** again. You can also ask the assistant, for example "Can this bookcase tip?" or "Show the centre of gravity". ## What counts in the weight - Each part, from the size of its blank and the density of its material. The densities come from EN 1991-1-1 (Eurocode 1), Annex A. For chipboard, the standard gives a range, so KerfCraft uses the lower value. A lighter unit tips sooner, so the result is on the cautious side. - The contents of each shelf that has a load. Set the load as in [Check a shelf for sag](/docs/how-to/furniture/check-a-shelf-for-sag/). - Accessories, for example handles and glass trim, are not included. If KerfCraft has no density for a material, it uses 5 kN/m³ (about 510 kg/m³) and tells you which parts use this value. ## The tipping tests KerfCraft does the tests on a freestanding unit only. A freestanding unit stands on the floor and is not fitted into a space. The tests use the loads from ASTM F2057-23, the standard for the stability of clothing storage units. US law (16 CFR part 1261) makes this standard mandatory for chests, dressers and wardrobes 27 in (686 mm) tall or more. KerfCraft uses the same loads as a guide for all units: 1. **Loaded, every door and drawer open.** The shelf contents are on the shelves, and all the doors and drawers are fully open. 2. **A child on an open drawer or door.** The unit is empty. A weight of 27.2 kg (60 lb) is on the front of the open drawer or door. KerfCraft uses the drawer or door that is furthest forward. KerfCraft does this test only when the unit has doors or drawers that open. 3. **A pull at the top.** The unit is empty and closed. A force of 44.5 N (10 lb) pulls forward at the top of the unit. The force is not higher than 1422 mm (56 in). For each test, KerfCraft compares two moments about the front edge of the unit. The weight behind the front edge holds the unit down. The weight in front of the edge and the pull tip the unit forward. When the tipping moment is equal to or more than the holding moment, the test fails. The result gives the ratio of the two moments. A tall, shallow bookcase often fails the pull test when it is empty. Books make it heavier, but the test is for an empty unit, because a unit is sometimes empty. ## Fix a unit to the wall If a unit has a tipping risk, fix it to the wall. Use an anti-tip strap or an angle bracket at the top back of the unit. Screw it into a stud or into masonry with the correct plug. To show the fixing in the model, add a small part at the top back of the unit. Give it a name such as **Anti-tip bracket** or **Wall strap**. KerfCraft finds a part with a name like this in the unit, or touching it. The result then changes to **fixed to the wall**. The check does not know if the screws go into a stud, so examine this yourself. Fix a unit to the wall if it is more than twice as tall as it is deep. This is also true when it passes the tests. ## Where the weight goes The check also says where the weight of the unit goes: - A unit on the floor sends its weight to the floor through the parts that touch the floor, for example the sides or the legs. A wall fixing only stops the unit tipping. It does not carry the weight. - A wall-hung unit or shelf hangs on its wall fixings. If its shelf contents weigh 20 kg or more, KerfCraft shows a warning. Use a French cleat or a rail screwed into studs or masonry, with fixings rated for the load, or stand the unit on the floor. The 20 kg limit is a rule of thumb, not a standard. ## What the check assumes - The unit is rigid and stands on a flat, hard floor. The tilt test on carpet in ASTM F2057-23 is not included. - The contents of a shelf sit at the middle of the shelf. Drawers and cupboards are empty. - The blank of a shaped part is a box. A shaped or turned part is thus a little heavier in the check than it really is. - The front of the unit is the side where the doors open. ## Related - [Check a shelf for sag](/docs/how-to/furniture/check-a-shelf-for-sag/) - [Make doors and drawers open](/docs/how-to/furniture/make-doors-and-drawers-open/) - [What KerfCraft checks and what you must check](/docs/explanation/what-kerfcraft-checks/)