Block Calculator
Free concrete block calculator. Enter wall size and block dimensions to get the number of CMU blocks, bags of mortar, and fill material for a concrete masonry wall.
About This Free Online Block Calculator
Our free block calculator estimates how many concrete masonry units (CMU blocks) you need for a wall, plus the mortar and fill. Enter the wall length and height, the block length and height (a standard block is 16×8 in including mortar joint), the mortar joint thickness, and a fill depth if you are grouting the cores, and the tool returns the block count, the wall area, the bags of mortar and the cubic yards of fill. Everything runs in your browser — perfect for masons, contractors and homeowners building retaining or foundation walls.
Features of Our Block Calculator
- CMU block count from wall size and block dimensions
- Mortar joint thickness included in the maths
- Bags of mortar for laying the wall
- Cubic yards of grout fill for the block cores
- Adjustable waste percentage for breakage
- 100% client-side and private — instant results, no signup
How to Use the Block Calculator
The Block Calculator works right in your browser — no signup, no installation. Follow these steps:
- Enter the wall length and height in feet.
- Set the block length and height in inches (standard is 16×8).
- Add a mortar joint and optional fill depth for grouted cores.
- Read off blocks, mortar and fill material.
Frequently Asked Questions About Block Calculator
How many concrete blocks do I need?
A standard 8×16 in block (including the 3/8 in mortar joint) covers 0.89 sq ft, so divide your wall area in square feet by that number and add about 5% for breakage. The calculator does this from your exact block and joint dimensions.
How many bags of mortar per 100 blocks?
As a planning estimate, figure about three 80 lb bags of premix mortar per 100 standard blocks. The calculator scales this to your block count.
What size is a standard concrete block?
The most common CMU is nominally 8×16 inches, which with a 3/8 in mortar joint actually measures 7.625×15.625 in. The calculator lets you enter any block size and joint thickness for accuracy.
Do I need to fill the block cores?
For reinforced or retaining walls you grout the cores solid, often with rebar. Enter a fill depth and the calculator works out the cubic yards of grout from the core volume of your block count.
Is this block calculator free?
Yes, completely free with no signup. All estimates run in your browser — nothing is uploaded or tracked.
Why Choose the Block Calculator?
The Block Calculator turns your measurements into real material estimates — bags, yards, sheets or gallons — so you buy the right amount the first time. It calculates instantly in your browser and never stores your project details.