Mortar Mix Calculator

This calculator splits your total Mortar Volume Needed into cement, lime, and sand proportions using the standard cement:lime:sand volume ratios for each mortar type -- Type M (1:0.25:3.5, highest strength), Type S (1:0.5:4.5), Type N (1:1:6, general purpose), and Type O (1:2:9, lowest strength). Sand quantity is dominated by Mortar Volume Needed rather than by which type you pick, because although the four types vary sharply in strength and cement content, sand consistently makes up about 74-75% of the total mix volume across all four -- Type M's sand share (3.5 of 4.75 total parts, or 73.7%) sits only a hair below Types S, N, and O, which all land at exactly 75%. Batch Size and Batch Yield are independent of everything else in this calculator: Batch Yield is simply your Batch Size reduced by 15% to account for the volume mortar loses to compaction and moisture loss as it's mixed, and neither Mortar Type nor Mortar Volume Needed affects it, nor does Batch Size affect the cement, lime, or sand quantities.

Cement and lime bag counts round up to the next whole bag (94 lb cement, 50 lb hydrated lime, both roughly 1 cubic foot per bag), so small volume changes will not always move the bag count. This tool estimates dry material quantities for planning -- always buy a small overage for waste and testing.