Medicine Cabinet Shelves Calculator

Design shelves for neat storage and smooth access. Choose sizes, materials, and spacing options. Export cut details and keep projects perfectly organized.

Calculator Inputs

Measure inside wall to wall.
Measure inside bottom to top.
Inside front to back panel.
Creates shelves + 1 compartments.
Common: 0.5, 0.75, 1.0.
For fit, clips, or liners.
Allows for wall bow or wiring.
Keeps shelf behind door and lip.
Extra room for hinge and door arc.
Space above the highest compartment.
Space below the lowest compartment.
Typical: 1 in or 32 mm system.
Affects weight and stiffness.
Lower sag gives lower safe load.
Used as an upper cap in results.

Example Data Table

Cabinet (W×H×D) Shelves Material Per-shelf cut size Compartment height
18×26×5 in 3 Plywood 17.75×4.25 in 6.25 in
20×30×6 in 4 Pine 19.75×5.00 in 5.40 in
45×70×13 cm 3 MDF 44.4×10.5 cm 16.0 cm

These examples assume typical clearances and rounded pin increments.

Formula Used

  • Shelf length = Cabinet width − 2 × side clearance.
  • Shelf depth = Cabinet depth − back clearance − front clearance − door clearance.
  • Available height = Cabinet height − top clearance − bottom clearance − (shelves × thickness).
  • Compartments = shelves + 1.
  • Clear height per compartment = Available height ÷ Compartments, then rounded to pin spacing.
  • Load estimate uses beam deflection: δ = 5wL⁴ / (384EI), with δ limited to L/N.

How to Use This Calculator

  1. Measure the cabinet’s interior width, height, and depth.
  2. Choose your shelf count and thickness for the boards.
  3. Set clearances for sides, back, front, and door swing.
  4. Pick a pin spacing so heights round to real holes.
  5. Select material and deflection rule for safe load guidance.
  6. Press calculate and review cut sizes, spacing, and exports.

Article

Accurate Measurements and Clearances

Shelf sizing starts with the cabinet’s true interior width, depth, and height. Measure surfaces, not door frames, and note any bumps from screws or clips. Subtract side, back, and front clearances so shelves slide in without scraping. Add door swing clearance when hinges, mirrors, or lips steal depth. Small gaps also allow liners, airflow, and wipe downs.

Compartment Heights and Adjustability

Compartment planning depends on shelf count, thickness, and top and bottom allowances. The calculator divides usable height into equal compartments, then rounds each compartment to your pin spacing. Use 1 inch spacing, or convert 32 mm systems by entering 3.2 cm. This aligns shelf locations with real holes, keeps spacing consistent, and leaves a margin for fine adjustments during installation.

Material Selection and Moisture Protection

Material choice affects weight, stiffness, and durability. Plywood typically stays flat and resists cracking, while MDF can sag more and dislikes repeated humidity cycles. Pine is light and economical but dents easily, and oak is strong yet heavier. Consider edge banding or polyurethane on exposed edges, because raw edges absorb moisture fastest. Sealed shelves clean better and reduce odor retention.

Load Guidance and Sag Control

Load guidance uses a deflection limit. The tool models a shelf as a simply supported beam with uniform load and caps sag to a rule such as L/180 or L/240. A conservative factor accounts for fasteners, time dependent creep, and bathroom humidity, keeping recommendations realistic. If you store glass bottles, prefer thicker shelves, shorter spans, or stronger materials. Always mount shelves level so loads distribute evenly.

Finishing, Liner Planning, and Layout

Finishing decisions depend on surface area. The calculator estimates face and edge area to plan paint, varnish, or liner coverage and reduce waste. For organization, place heavy bottles low, keep daily items near eye level, and reserve top space for light, used supplies. Group items by height, then set compartment spacing to avoid stacking, which often improves access and prevents spills.

FAQs

1) Should I measure the cabinet before removing old shelves?

Yes. Measure the clear interior width, height, and depth at several points. Walls can be out of square, so use the smallest measurement to prevent shelves from binding.

2) What pin spacing should I use for adjustable shelves?

Match your hardware. Many cabinets use 1 inch spacing, while some systems use 32 mm. Enter the spacing that matches your drilled holes so compartment heights round cleanly.

3) How do I increase the safe load per shelf?

Reduce the shelf span, increase thickness, or choose a stiffer material like plywood or oak. Using a stricter deflection rule also reduces sag for the same stored weight.

4) Why does the calculator include door swing clearance?

Hinges, door lips, and mirrors can reduce usable depth. Adding door swing clearance prevents stored items from rubbing the door and keeps the door closing smoothly.

5) Is MDF a good choice in a bathroom?

MDF can work if sealed well, but it is sensitive to moisture and can swell at edges. If humidity is high, plywood or a sealed hardwood shelf is usually safer.

6) What should I export and save after calculating?

Save the per shelf cut size, compartment height, and load guidance. The CSV helps track multiple cabinet plans, and the PDF is handy to bring to the workshop.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.