Ok Mm. Calculator

Professional PCB Copper Thickness Conversion Tool

Thickness in mm 0.0000

Thickness in Microns (μm) 0.00

Understanding Copper Weight Conversions (Oz to mm)

In the Printed Circuit Board (PCB) industry, copper thickness is rarely measured directly in millimeters during the design phase. Instead, it is expressed in ounces (oz). This "oz" measurement refers to the weight of copper spread evenly over one square foot of area.

Our OK mm Calculator (Ounce to Millimeter) allows engineers and hobbyists to accurately determine the physical height of a copper trace. This is critical for calculating trace impedance, current carrying capacity, and thermal management.

The Standard Formula

While the exact thickness can vary slightly based on manufacturing processes, the industry standard conversion used in this calculator is:

• 1 oz/ft² = 1.37 mils
• 1 oz/ft² = 0.0348 millimeters (mm)
• 1 oz/ft² = 34.8 micrometers (μm)

Common PCB Copper Weight Table

Weight (oz)	Thickness (mm)	Thickness (μm)
0.5 oz	0.0174 mm	17.4 μm
1.0 oz (Standard)	0.0348 mm	34.8 μm
2.0 oz (Heavy)	0.0696 mm	69.6 μm
3.0 oz	0.1044 mm	104.4 μm

How to use this calculator

1. Enter the copper weight in ounces (e.g., for standard boards, enter 1).
2. Click Calculate Thickness.
3. The tool will instantly provide the thickness in both millimeters (mm) and micrometers (μm).

Note: Theoretical values are used. Actual finished copper thickness may vary slightly due to plating and etching processes during PCB fabrication.

function calculateThickness() { var inputOz = document.getElementById('ozInput').value; var resultArea = document.getElementById('resultArea'); var resMm = document.getElementById('resMm'); var resUm = document.getElementById('resUm'); if (inputOz === "" || isNaN(inputOz) || inputOz <= 0) { alert("Please enter a valid positive number for copper weight."); resultArea.style.display = "none"; return; } var ozValue = parseFloat(inputOz); // 1 oz copper = 0.0348 mm var mmValue = ozValue * 0.0348; var umValue = mmValue * 1000; resMm.innerHTML = mmValue.toFixed(4) + " mm"; resUm.innerHTML = umValue.toFixed(2) + " μm"; resultArea.style.display = "block"; }