Shelf Sag Calculator (Sagulator)

Calculate shelf sag with the Sagulator

Ever been worried that the shelves won’t be strong enough?

Will they break?

Finally, an end to all your questions! We found the Sagulator, which helps you to design your own wooden shelf tailored to your needs. A big thanks to Bill at WoodBin for letting us share his amazing online calculator! Here is what it looks like:

Check out the Sagulator

What is shelf sagging?

If you’ve ever loaded a shelf with a lot of items, you may have noticed it starting to dip in the centre. With increased weight and prolonged storage, the shelf will dip down even further, creating an unsightly curve and possibly even breaking under the weight.

Calculating shelf sag is essentially the same as figuring out beam deflection, which depends on various factors like shelf thickness, shelf span, and modus of elasticity of the material used. At Shelving Shop Group, we offer two types of wooden shelving that can be customised to your ideal dimensions. By using this handy shelf sag calculator, you can determine how big your shelf needs to be to support your goods.

How to use the shelf sag calculator

1. Select shelf material

Choose either MDF – MD (medium density) or melamine. Note that this shelf weight calculator is only for wood, not steel, as the stiffness of metals is much higher.

2. Select fixture type

Pick whether your shelf is attached on the sides or simply free-floating. Our wooden shelves are floating by default, but the MDF boards can also be integrated with our pallet racking or long-span shelving.

3. Select shelf load and distribution

Estimate the weight you plan to load on your shelf and if it will be centred in one place or spread along the shelf’s length.

4. Enter shelf span, shelf depth and shelf thickness

Measure how long, wide and thick you expect your shelf to be. Note that our melamine shelves have set length and depth options, though we can also precision cut them to your desired size at an additional cost.

5. Add an edging strip (optional)

Adding an edge strip in the same material can increase the stiffness of the lumber, giving your shelves a stronger design and longer life. The ‘thickness’ of the strip will be in the same direction as the shelf’s depth, while the ‘width’ of the strip will be in the same direction as the shelf’s thickness.

Tips for managing shelf sag

• Results from the wood sag calculator can vary in real life, so it’s good to be on the safe side and order shelves that have a greater calculated load limit than what you require.
• The Sagulator only calculates the initial deflection. Since wooden shelving is expected to sag an additional 50% over time, a suggested target for allowable sag is 0.02″ per foot or less.
• Evenly store your items along the beam, ensuring that the load is distributed equally.
• Consider stainless steel shelving instead of wood if you need heavy-duty materials that can store bulkier products in the same area of space, such as retail stores or warehouses.
• To optimise your calculations, check out the handy tips for decreasing beam deflection at the bottom of the Sagulator page.