Concrete Calculator

The Concrete Calculator estimates concrete volume, material quantities, bag count, and rough cost for DIY and small construction work in Japan. It is useful for slabs, foundations, fence posts, block work, and mortar repairs when you need to know cubic meters and how many bags to buy.

Enter dimensions, choose a concrete or mortar preset, and the tool estimates cement, sand, gravel, water, overage, and cost. You can edit material prices to see both tax-exclusive totals and a tax-included estimate based on the standard Japanese consumption tax rate. For larger jobs, ready-mix alerts help you decide when hand mixing may be impractical.

Before You Estimate

Required quantity changes significantly with thickness. For slabs and walkways, decide the thickness first. For fence posts, confirm hole diameter and depth. For stairs, enter the number of steps, rise, tread, and width. When pouring directly on uneven ground, use a larger overage percentage to cover gaps and loss.

The result is a purchasing estimate, not a structural design. For work involving structural strength, reinforcement, soil conditions, frost, laws, or construction standards, follow drawings, mix designs, contractors, or qualified professionals.

Related Tools Use the [Volume Calculator](/en/calc/volume-shape-calculator/) for shape-only volume checks, and the [Area Converter](/en/calc/area-converter/) for square meters, tsubo, and other area units. For comparing material prices, use the [Unit Price Compare](/en/calc/unit-price-compare/). For nearby renovation estimates, the [Paint Calculator](/en/calc/paint-calculator/) and [Wallpaper Calculator](/en/calc/wallpaper-calculator/) are also useful.

Everything runs locally in your browser, so your text, numbers, or files are not uploaded to a server. No account is required, and the tool is free to use on desktop or mobile.