Compression Ratio Calculator

This calculator requires the use of Javascript enabled and capable browsers.

First, click the Clear button. Next, enter the measurement designation in either inches, 1, or millimeters, 2. Enter the cylinder bore diameter. Enter the piston stroke length. Click on Calculate Displacement. The value will be returned in CR, Compression Ratio from ALL input values excluding Total Volume. You can also calculate Total Volume from bore, stroke, and CR. This returned value for volume should be measured with the piston at top dead center, with all valves closed and with the head gasket installed, or, Calculate Combustion Chamber Volume from ALL input values except Combustion Chamber Volume and Total Volume by entering the required values and clicking on the proper Calculate button. To do another, click the Clear button and then enter a new set of values.

Note: Calculated accuracy of current Javascript enabled browsers is generally 16 places.

Enter Bore/Stroke Designation Type
1 = Inches 2 = Millimeters
Enter Cylinder Bore Size   
Enter Piston Stroke Length   
Enter Head Gasket Bore Diameter
Enter Compressed Head Gasket Thickness
Enter Combustion Chamber Volume In CCs
Enter Piston Dome Volume In CCs Negative For Dished Pistons (Use '-')
Enter Piston Deck Clearance Negative If ABOVE Deck (Use '-') :
Calculated Static Engine Compression Ratio :1
Total Displacement Volume cc