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Scaffolding calculator
Bays = run length / section length, rounded up. Lifts = platform height / frame height, rounded up. Frames = (bays + 1) x lifts. A 42 ft run to 25 ft in 7 ft frame scaffold is 6 bays, 4 lifts and 28 frames.
Your job
System
5 ft wide frames with cross braces and coupling pins.
Elevations
Bays and platform
Platforms, guardrails and access
Top rail 38 to 45 in, midrail about halfway, toeboards at least 3-1/2 in. Access is required when the platform is more than 2 ft above or below the access point.
Over 10 ft: everyone on the scaffold needs fall protection (guardrails on all open sides and ends, or personal fall arrest).
OSHA: designed by a qualified person, and erected, moved or taken down only under the supervision of a competent person.
Estimate only. Follow the manufacturer's instructions and the scaffold design for ties, bracing and loads.
The first run in elevation: frames or posts, lifts, the decked platform with guardrails, braces and ties.
Bays
6bays
4 lifts high, frame scaffold
Lifts
4lifts
6 ft 4 in apart, top platform at 25 ft 4 in
Frames
28
End frames on every section, every lift
Planks or decks
18
3 across a 5 ft width
Ties
3
At 19 ft
| Component | Size | Qty |
|---|---|---|
| Frames | 5 ft x 6 ft 4 in walk-through | 28 |
| Cross braces (both faces, every section and lift) | 7 ft | 48 |
| Coupling pins | 42 | |
| Hook-on decks | 19 in x 7 ft | 18 |
| Guardrail posts (top level) | 14 | |
| Guardrails, top rail and midrail | 7 ft | 12 |
| End guardrails, top rail and midrail | 5 ft | 4 |
| Toeboards | 7 ft | 6 |
| End toeboards | 5 ft | 2 |
| Base plates or screw jacks | 14 | |
| Mud sills | 14 | |
| Ladder access (hook-on, attachable or stair tower) | 25 ft 4 in climb | 1 |
| Ties | at each end, at most 30 ft apart | 3 |
The working, with your numbers
- 1. Bays42.0 / 7, rounded up= 6 bays
- 2. Lifts25.0 / 6 ft 4 in, rounded up= 4 lifts
- 3. Frames(bays + 1) per run x lifts= 28
- 4. Planksbays x 3 across x planked levels= 18
- 5. Ties4:1 height = 4 x 5 = 20 ft; levels 1 x (run / 30 ft, rounded up, + 1)= 3
Scaffolding estimate (metremate.com/us/calculators/scaffolding-calculator)
- Frame scaffold: 42.0 ft long, top platform at 25 ft 4 in
- 6 bays of 7 ft x 4 lifts
- Frames, 5 ft x 6 ft 4 in walk-through: 28
- Cross braces (both faces, every section and lift), 7 ft: 48
- Coupling pins: 42
- Hook-on decks, 19 in x 7 ft: 18
- Guardrail posts (top level): 14
- Guardrails, top rail and midrail, 7 ft: 12
- End guardrails, top rail and midrail, 5 ft: 4
- Toeboards, 7 ft: 6
- End toeboards, 5 ft: 2
- Base plates or screw jacks: 14
- Mud sills: 14
- Ladder access (hook-on, attachable or stair tower), 25 ft 4 in climb: 1
- Ties: 3
- Estimate only. A qualified person designs the scaffold and a competent person supervises the erection.
The formula, in plain words
- 1Bays per run = run length / section (bay) length, rounded up.
- 2Lifts = top platform height / lift height (the frame height, 78.74 in for ringlock, or 6 ft 6 in runners for tube and clamp), rounded up.
- 3Frame scaffold: frames = (bays + 1) x lifts, cross braces = 2 x bays x lifts, coupling pins = 2 x (bays + 1) x (lifts - 1).
- 4Planks or decks = bays x planks across x planked levels; guardrails, midrails and toeboards on the open side and ends of each planked level.
- 5Ties (OSHA 1926.451(c)(1)): once the height passes 4 times the base width, at the nearest level to that height, then every 26 ft (20 ft for 3 ft wide or less), at each end and at most 30 ft apart.
Worked example
A 42 ft elevation with the top platform at about 25 ft, in frame scaffold with 5 ft x 6 ft 4 in walk-through frames, 7 ft cross braces, 19 in decks and the top level planked.
- 1.Bays: 42 / 7 = 6. Lifts: 25 / 6 ft 4 in = 3.9, so 4, and the top platform lands at 25 ft 4 in.
- 2.Frames: (6 + 1) x 4 = 28. Cross braces: 2 x 6 x 4 = 48. Coupling pins: 2 x 7 x 3 = 42.
- 3.Decks: three 19 in decks fit a 5 ft frame, so 6 x 3 = 18 decks of 7 ft.
- 4.Ties: 4 x 5 ft = 20 ft, so one tie level at the 19 ft frame top, with 42 / 30 = 1.4, rounded up to 2, + 1 = 3 ties.
Answer: 6 bays, 4 lifts, 28 frames, 48 cross braces, 18 decks and 3 ties.
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Try MetreMate freeHow to measure it
- Measure each elevation along the building in linear feet off the floor plan or site plan, including returns and setbacks.
- Measure from grade to where the top working platform has to be, off the elevations.
- Check the frame, brace and plank sizes your supplier rents, and the tie and bracing pattern in the manufacturer's instructions.
Where the numbers come from
Every default in the calculator comes from a published source. We list the source next to it so you can check.
| What | Value | Source |
|---|---|---|
| Walk-through frame 5 ft wide x 6 ft 4 in high; 7 ft or 10 ft cross braces set the section length | 5 ft x 6 ft 4 in | Bil-Jax walk-through frame scaffold set (dealer listing) (checked 2026-10-07) |
| Walk-through frame 76 x 60 in, two coupling pins included | 76 x 60 in | MetalTech M-MA7660PS 76 x 60 in walk-through frame (retailer listing) (checked 2026-10-07) |
| Frame 5 ft wide x 5 ft high | 5 x 5 ft | MetalTech M-MF6060PS 5 x 5 ft frame (retailer listing) (checked 2026-10-07) |
| Frames braced by cross, horizontal or diagonal braces and joined by coupling or stacking pins (1926.452(c)(2), (3)); a set is 2 frames, 2 cross braces and 4 stack pins | 2 cross braces per section | Bil-Jax walk-through frame scaffold set (dealer listing) (checked 2026-10-07) |
| Hook-on aluminum and plywood platform 19 in wide x 7 ft long | 19 in x 7 ft | MetalTech, aluminum platform with 5/8 in plywood deck (checked 2026-10-07) |
| The most common scaffold plank lengths are 7, 8 and 10 ft | 7 8 and 10 ft | Bil-Jax, scaffold plank dimensions, lengths and specifications (checked 2026-10-07) |
| Four guardrail posts support the horizontal guardrails on one section; rails in 5, 7 and 10 ft | 4 posts per section | MetalTech, guardrail post with wedge clamp (checked 2026-10-07) |
| Ringlock rosettes every 0.5 m (19.69 in); verticals 19.69 to 118.11 in (0.5 to 3.0 m) | 19.69 in | DSS RingLock catalog (2019) (checked 2026-10-07) |
| Ringlock ledgers in foot sizes: 5 ft = 60.00 in, 7 ft = 83.86 in, 8 ft = 96.06 in, 10 ft = 120.12 in; 3 ft = 35.98 in, 4 ft = 48.03 in | 83.86 in (7 ft ledger) | DSS RingLock catalog (2019) (checked 2026-10-07) |
| Vertical diagonals rise 78.74 in (2.0 m) per lift | 78.74 in (2.0 m) | DSS RingLock catalog (2019) (checked 2026-10-07) |
| Tube and coupler post spacing: light 4 x 10 ft, medium 4 x 7 ft, heavy 6 x 6 ft; bearers in the shorter direction; 1.90 in OD tube | 10 ft (light duty) | OSHA 29 CFR 1926 Subpart L, Appendix A (non-mandatory guidelines) (checked 2026-10-07) |
| Maximum vertical spacing of runners 6 ft 6 in | 6.5 ft (6 ft 6 in) | OSHA 29 CFR 1926 Subpart L, Appendix A (non-mandatory guidelines) (checked 2026-10-07) |
| 2x10 nominal-thickness plank spans: 8 ft at 25 psf, 6 ft at 50 psf (75 psf: 6 ft for full-thickness undressed lumber) | 8 ft at 25 psf | OSHA 29 CFR 1926 Subpart L, Appendix A (non-mandatory guidelines) (checked 2026-10-07) |
| A nominal 2x10 is actually 1-1/2 x 9-1/4 in | 9.25 in | Kreg Tool, understand lumber sizing (checked 2026-10-07) |
| Dimensional lumber stock lengths, in 2 ft steps (8, 10, 12, 14 and 16 ft most stocked) | 8 to 20 ft | Hunker, standard lengths for dimensional lumber (checked 2026-09-20) |
| Light duty 25 psf, medium 50 psf, heavy 75 psf | 25 psf (light) | OSHA 29 CFR 1926 Subpart L, Appendix A (non-mandatory guidelines) (checked 2026-10-07) |
| Transverse X bracing at the ends and at least every third set of posts and every fourth runner; longitudinal bracing in both directions from the end posts to the top at about 45° (1926.452(b)(2), (3)) | 3 sets of posts | OSHA 29 CFR 1926.452, Additional requirements for specific types of scaffolds (checked 2026-10-07) |
| Ties above a 4:1 height to base width, then every 20 ft (3 ft wide or less) or 26 ft (wider), top tie within 4:1 of the top, at each end and at most 30 ft apart (1926.451(c)(1)(ii)) | 26 ft | OSHA 29 CFR 1926.451, General requirements (scaffolds) (checked 2026-10-07) |
| Top rail 38 to 45 in above the platform, midrail about halfway, on all open sides and ends (1926.451(g)(4)) | 38 to 45 in | OSHA 29 CFR 1926.451, General requirements (scaffolds) (checked 2026-10-07) |
| Toeboards at least 3-1/2 in high with no more than 1/4 in clearance (1926.451(h)(4)) | 3.5 in min | OSHA 29 CFR 1926.451, General requirements (scaffolds) (checked 2026-10-07) |
| Platforms fully planked, at least 18 in wide, gaps no more than 1 in, no more than 14 in from the face of the work (1926.451(b)) | 18 in min | OSHA 29 CFR 1926.451, General requirements (scaffolds) (checked 2026-10-07) |
| Plank ends extend 6 to 12 in past the support (10 ft or shorter); abutted planks overlap at least 12 in over supports (1926.451(b)(4), (5), (7)) | 6 to 12 in | OSHA 29 CFR 1926.451, General requirements (scaffolds) (checked 2026-10-07) |
| Access by ladder, stair tower or ramp when the platform is more than 2 ft above or below the access point (1926.451(e)(1)) | 2 ft | OSHA 29 CFR 1926.451, General requirements (scaffolds) (checked 2026-10-07) |
| Ladders on scaffolds more than 35 ft high need rest platforms at 35 ft maximum intervals (1926.451(e)(2)(iii)) | 35 ft | OSHA 29 CFR 1926.451, General requirements (scaffolds) (checked 2026-10-07) |
| Supported scaffold legs bear on base plates and mud sills or other firm foundation (1926.451(c)(2)) | 1 per leg | OSHA 29 CFR 1926.451, General requirements (scaffolds) (checked 2026-10-07) |
| Fall protection for anyone on a scaffold more than 10 ft above a lower level (1926.451(g)(1)) | 10 ft | OSHA 29 CFR 1926.451, General requirements (scaffolds) (checked 2026-10-07) |
| Designed by a qualified person, erected under a competent person; frame and tube and coupler scaffolds over 125 ft designed by a registered professional engineer (1926.451(a)(6), (f)(7); 1926.452(b)(10), (c)(6)) | 125 ft | OSHA 29 CFR 1926.452, Additional requirements for specific types of scaffolds (checked 2026-10-07) |
Manufacturers named here are the source of the number, not a recommendation. Confirm quantities with your supplier.
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