We will manufacture the opening size of your canvas floater frame to the size you enter plus 3-5mm(approx) allowance. If you would like a gap larger than 2mm(approx) between the frame and your canvas picture it is important to increase the size you enter by the desired amount. Our recommendation would be to measure your canvas picture and add 10mm to each dimension. This will allow suitable movement and space the canvas away from the edge so it appears to float.
You should also note the internal depth of the canvas floater frame which is detailed within the product description, and ensure this is suitable for the thickness of your canvas. It is perfectly normal for the thickness of your canvas to be slightly more or less than the internal depth of the frame.
When measuring your canvas it is important to not presume that it will be square. Measure each outer edge of the stretched canvas, i.e. top, bottom, left and right, and use the larger of the two measurements(if there is a difference) when calculating the size you enter into our website.