From this site

One project, every trade

Each calculator adds its lines to a single estimate — consolidated BOM, schedule and cash-flow included.

Open My Project →

ACI 347 Column Formwork Rate-of-Placement Pressure Calculator

Calculate the maximum lateral pressure on column formwork from ordinary (non-SCC) concrete, using the ACI 347R rate-of-placement formula.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-27 · v1.2.0

Market
Imperial · sales tax
9.84 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Maximum lateral formwork pressure

1476.38 psf

Check your inputs

Column forms are frequently filled faster than the concrete below can stiffen, so full hydrostatic pressure is a realistic design case rather than a conservative one. That is the main way columns differ from walls.

Unit weight coefficient Cw
1.03 (dimensionless)
Full hydrostatic ceiling
1476.38 psf

At the values currently entered, the maximum lateral formwork pressure works out to 1476 psf. The largest intermediate quantity is full hydrostatic ceiling, at 1476 psf — check that step first if the total looks off. Confidence is moderate: the method is sound, but real materials and site conditions vary. Figures are shown for United States, where IRC 2024 is the governing residential reference; switch the market above if you are building elsewhere.

Add the equipment this sizes

This result is a specification — 1,476.378 psf — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • ACI 347R-14(21) Guide to Formwork for Concrete, Section 2.2.2, Eq. 2.2 (for forms where no plan dimension exceeds 6.5 ft/2m, i.e. columns): Pmax = Cw×Cc×[150 + 9000R/T] psf, with a floor of 600×Cw psf and a ceiling of full hydrostatic pressure (w×h) — this equation has no stated upper rate-of-placement limit in the Guide (unlike the wall equation's 15 ft/hr cap), reflecting that column forms are typically filled quickly enough that the full-hydrostatic ceiling governs naturally at high rates. Cw and Cc coefficients are identical to and defined the same way as this site's companion wall formwork pressure calculator. This formula ONLY applies when slump ≤7in and normal internal vibration to ≤4ft depth is used — SCC and high-slump/retarded mixes must use this site's full-hydrostatic SCC formwork pressure calculator instead.

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Why do columns see higher pressure than walls?
Because of pour rate. A column is a small plan area filled in minutes, so the concrete at the bottom is still fluid when the top arrives — the full height acts hydrostatically. A wall of the same height is filled over a much longer period, and its lower concrete stiffens and starts carrying itself before the pour finishes. The geometry is the same; the timing is not.
Does a slower pour reduce the pressure?
Yes, and it is the most effective control available. Pressure depends on how much of the concrete is still fluid, so slowing the rate lets the lower lifts stiffen and cap the pressure envelope well below hydrostatic. It costs programme time, and on a tall column it is often cheaper than the formwork needed to resist a full hydrostatic head.
What makes the concrete stay fluid longer?
Cold weather, retarding admixtures, high slump, and high cement replacement with GGBS or fly ash. Every one of these extends the working time, which is usually the intention — and every one raises the formwork pressure as a side effect. A mix changed for placeability without telling the formwork designer is a recognised route to a blowout.
Does vibration increase the pressure?
Yes. Vibrating re-liquefies concrete that had begun to stiffen, undoing the pressure relief that time was providing, and deep immersion of the poker does it several lifts down. Formwork design assumes normal internal vibration; prolonged or excessively deep vibration takes the pressure back toward hydrostatic.