Calculator
Example data table
| Opening (W×H) | Config | Gaps (top/bottom/side/between) | Panel size output | Sweep clearance |
|---|---|---|---|---|
| 48 × 80 in | 2-panel | 0.25 / 0.50 / 0.125 / 0.125 | ~23.75 × 79.25 in | ~13.13 in |
| 96 × 84 in | 4-panel | 0.25 / 0.50 / 0.125 / 0.125 | ~23.38 × 83.25 in | ~12.94 in |
| 1200 × 2100 mm | 2-panel | 6 / 12 / 3 / 3 | ~591 × 2082 mm | ~334 mm |
Examples are approximate; hardware varies by brand and weight rating.
Formula used
Panel height
PanelHeight = OpeningHeight − TopGap − BottomGap − TrackAllowance
TrackAllowance is helpful when a top track reduces usable height in a garden shed header.
Panel width
UsableWidth = OpeningWidth − 2·SideGap − (Panels−1)·BetweenGap
PanelWidth = UsableWidth ÷ Panels
For a 2-panel opening there is 1 between gap; for 4 panels there are 3.
Projected sweep clearance
Sweep ≈ PanelWidth/2 + PivotSetback + DoorThickness/2 + ExtraSweep
This estimates how far the folding edge may swing into an aisle near benches or planters.
How to use this calculator
- Measure your finished opening width and height at multiple points.
- Pick a configuration: two panels for narrow openings, four for wide ones.
- Set clearances to match outdoor movement, paint, and hardware.
- Press Submit to view results immediately above the form.
- Download CSV or PDF to keep with your garden build notes.
Practical guidance
Clearance planning for outdoor openings
Outdoor bifold doors face moisture, heat, and frame movement. Start with a true rough opening measurement at the tightest point, then size panels to clear the jambs, header, and floor. This calculator converts your clearances into usable width and height so panels close without rubbing, even when paint builds up or wood swells after watering and rain, week after week, in many climates.
Choosing practical gaps
Small gaps look neat, but garden environments punish tight tolerances. Side gaps help panels stay free when hinges shift or a shed settles. A between-panel gap prevents the fold line from binding and leaves space for weatherstripping. Bottom clearance matters most on patios and pavers where grit collects; a slightly larger gap reduces scraping and extends hinge life.
Accounting for track and threshold
Hardware stack-up changes your effective height. If a top track, hanger plate, or mounting block lowers the running surface, include it as track allowance. For thresholds, remember that mats, trays, or raised sills reduce clearance. In damp areas, add a modest top gap to limit sticking after seasonal expansion. Re-check the opening after cladding or trim is installed, because finish layers can steal millimeters quickly.
Estimating swing and sweep space
Garden workspaces often have benches, compost bins, and tool racks close to doors. The sweep estimate combines half panel width, pivot setback, thickness, and extra buffer to approximate the space the folding edge may enter while opening. Use it to keep handles from knocking pots and to preserve safe walking clearance near steps or narrow paths.
Field checks before cutting panels
Treat calculator outputs as a planning baseline, then verify with real parts. Dry-fit the track, pivots, and hinges; confirm the pivot setback and hanger positions match your kit. Check the floor for slope, and measure diagonals to spot racking. If the opening is out of square, keep the panel width and adjust gaps slightly so the reveal remains even from top to bottom.
FAQs
What opening measurement should I use?
Use the smallest width and the smallest height you measure. Outdoor frames can bow, so sizing to the tightest point reduces binding risk and improves seasonal reliability.
Should I choose two panels or four panels?
Two panels suit narrow shed doors and simple access. Four panels reduce individual panel width on wide openings, improving handling and making space planning easier around benches and storage.
How much bottom clearance is typical outdoors?
A larger bottom gap helps with grit, pavers, and mild slope. If you expect mud or mats, increase the bottom gap slightly, then confirm the door still covers the opening visually.
Why include a between-panel gap?
The fold line needs breathing room for hinges and weather movement. A small gap reduces rubbing during folding and allows room for seals, especially when panels are painted or varnished.
Does door thickness affect clearance?
Thickness influences sweep and potential interference near planters or racks. Thicker doors and bulky handles project farther, so add extra sweep clearance to avoid collisions in tight garden aisles.
Can I rely on the results without checking hardware instructions?
No. Tracks and pivots vary by brand and weight rating. Use the calculator to estimate, then confirm required gaps and mounting allowances from your hardware guide before final cutting.