The workbench · Version 1.0
Three-axis fit checker
Check the numbers before choosing a sleeve, organizer or packing pouch. The result describes a rectangular space, not real-world compatibility.
Enter the object’s exterior and the container’s usable interior. A missing dimension produces “unknown.” A numerical pass does not account for openings, curves, seams, compression or tolerances and is never a structural-load or airline-acceptance approval.
Compare the three axes
Three ordinary worked cases
- Laptop sleeve. Object 32 × 22 × 2.2 cm; sleeve interior 33 × 23 × 3 cm; 0.2 cm extra clearance per side. Remaining allowances are 0.6, 0.6 and 0.4 cm. Check the sleeve opening and your actual device separately.
- Drawer tray. Tray exterior 28 × 20 × 4 cm; usable drawer 29 × 21 × 5 cm; 0.3 cm per side; no rotation. Remaining allowances are 0.4 cm on each axis. A handle, runner or curved corner can invalidate the rectangular estimate.
- Soft packing pouch. A rectangular estimate of 30 × 20 × 10 cm in a 21 × 31 × 11 cm space fails in the entered orientation. If the packed contents genuinely permit any face, swapping width and depth gives 1 cm of allowance per axis before extra clearance. This says nothing about airline rules or packed-bag acceptance.
Formula and honest boundaries
Convert all lengths to centimeters: millimeters ÷ 10; inches × 2.54. For each allowed axis mapping, remaining allowance = interior length − exterior length − 2 × per-side clearance. All positive values mean numerical clearance. A zero value is uncertain, not a physical pass. Negative on any axis rejects that orientation. Supported inputs are positive finite dimensions no larger than one billion centimeters; clearance is nonnegative.
Measure the narrowest usable opening and interior position, not the largest outer marketing dimension. Do not subtract manufacturer padding twice if the quoted dimension is already internal. A liters rating cannot replace three usable measurements. Flexible fabric is not a license to assume that valuable gear can be forced into a marginal space.
Use the relevant measuring guide
- Laptop sleeve: internal versus external dimensions.
- Drawer clearances and divider range.
- Plan packing-cube dimensions.
Sources and calculation provenance
NIST Guide to SI, Appendix B.8 supplies the exact inch-to-centimeter factor (read November 7, 2026). The rectangular clearance formula and synthetic examples are our own arithmetic, not manufacturer fit claims. Inputs remain in memory, with no upload or local-storage persistence.
Part of Home office. The calculation is useful without buying or signing up.
Citation and revision
The Guide Index, “Three-axis fit checker”, version 1.0, November 7, 2026. Canonical: https://theguideindex.com/tools/fit-checker/. Original calculations and synthetic examples, not a vendor test or certification.