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Preliminary flotation estimator

Check a structure before you quote it. Type the geometry and the groundwater depth and you get a factor of safety against flotation instantly — and if it fails, the extra dead weight and base extension it would take to fix. Estimating only; see the note under the tool.

Buoyancy check — round manholes, wet wells & box structures

Dead weight only · groundwater at the depth you enter · openings and hardware not modelled

Unit weights held at concrete 150 pcf, soil 120 pcf, water 62.4 pcf. The sealed calculation uses your project's actual values.

Factor of safety against flotation … starting the estimator…
Get this structure sealed →

Send us the shop drawing and the boring log. Sealed package back in 1–5 business days.

Preliminary estimating tool — not an engineering document. This calculator is provided free for rough screening and quoting only. It is not sealed, is not a professional engineering service, and creates no engineer–client relationship. It models dead weight only and ignores pipe penetrations, hatches, ring and cover, grade rings, stored liquid, equipment, side friction, soil wedge, construction-stage conditions and site-specific soil data — all of which the sealed calculation accounts for. Do not use these results for design, fabrication, submittal or construction, and do not rely on them. Oasis Engineering accepts no liability for any use of this tool. Verify every result with a licensed professional engineer.