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Sump Pit & Catch Basin Concrete Calculator

Estimate the concrete volume needed to pour an open-top sump pit or catch basin, accounting for the hollow interior.

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 2026-08-26 · v1.0.0

Market
Imperial · sales tax
3.94 ft3.94 ft0.49 ft
Schematic, drawn to the proportions you entered — not to scale on screen.
Who is doing the work?

Waste is set to 5% by hand. Pick a tier above to replace it, or keep your own figure.

Concrete volume needed

1.03 yd³

Check your inputs

Assumes a simple open-top rectangular box with uniform wall and base thickness — real sump designs often have a sloped or stepped base for pump clearance.

Outer block volume
1.88 yd³
Interior void volume
0.9 yd³
Base volume (no waste)
0.98 yd³

With the figures above, the concrete volume needed comes to 0.79 m³. Behind that figure, outer block volume is the biggest single quantity at 1.44 m³; start there if the total looks wrong. The method behind this is well established, though site conditions and material batches will move it somewhat. This is calculated for United States and cites IRC 2024. Building in another market? Change the selector above so the units and code reference follow.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

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

  • Concrete volume = outer block volume minus the hollow interior void (an open-top box with walls and a base of uniform thickness)

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 is the interior void height different from the outer height?
The base slab needs its own thickness, so the hollow interior only starts above the base — it doesn't extend the full outer height.
Does this include a lid or cover?
No — this is an open-top pit. Add a separate slab volume if you're pouring a cover in place.