A method for providing closed loop control of an untensioned product length of a web moving through a printing press under tension during production, the printing press including at least one printing unit having a plate cylinder, a blanket cylinder, and an impression cylinder, the method comprising, using a controller: while the printing press is printing on the web: using the controller or a different controller: generating a calculated untensioned product length (L 0), wherein the step of generating further includes: determining a tensioned repeat length (L 1) of the web in a span of the printing press while the web is moving through the printing press under tension; determining an elastic strain (ε 1) of the web in the span of the printing press while the web is moving through the printing press under tension; and calculating an untensioned product length L o (t) of the web in the span of the printing press while the web is moving through the printing press under tension as a function of the tensioned repeat length (L 1) and the elastic strain (ε 1), the method further comprising: receiving the calculated untensioned product length L o (t) of the web in the span of the printing press while the web is moving through the printing press under tension, comparing L 0 (t) to a previously stored untensioned product length setpoint L setpoint, maintaining closed loop control of the untensioned product length by controlling one or more components on the printing press as a function of said comparing step, and repeating the steps receiving, comparing, maintaining and controlling over time while the printing press is printing on the web, wherein the step of maintaining comprises varying an image velocity of the printing press by varying a rotational velocity of the plate and blanket cylinders. while the printing press is printing on the web: using the controller or a different controller: generating a calculated untensioned product length (L 0), wherein the step of generating further includes: determining a tensioned repeat length (L 1) of the web in a span of the printing press while the web is moving through the printing press under tension; determining an elastic strain (ε 1) of the web in the span of the printing press while the web is moving through the printing press under tension; and calculating an untensioned product length L o (t) of the web in the span of the printing press while the web is moving through the printing press under tension as a function of the tensioned repeat length (L 1) and the elastic strain (ε 1), using the controller or a different controller: generating a calculated untensioned product length (L 0), wherein the step of generating further includes: determining a tensioned repeat length (L 1) of the web in a span of the printing press while the web is moving through the printing press under tension; determining an elastic strain (ε 1) of the web in the span of the printing press while the web is moving through the printing press under tension; and calculating an untensioned product length L o (t) of the web in the span of the printing press while the web is moving through the printing press under tension as a function of the tensioned repeat length (L 1) and the elastic strain (ε 1), generating a calculated untensioned product length (L 0), wherein the step of generating further includes: determining a tensioned repeat length (L 1) of the web in a span of the printing press while the web is moving through the printing press under tension; determining an elastic strain (ε 1) of the web in the span of the printing press while the web is moving through the printing press under tension; and calculating an untensioned product length L o (t) of the web in the span of the printing press while the web is moving through the printing press under tension as a function of the tensioned repeat length (L 1) and the elastic strain (ε 1), determining a tensioned repeat length (L 1) of the web in a span of the printing press while the web is moving through the printing press under tension; determining an elastic strain (ε 1) of the web in the span of the printing press while the web is moving through the printing press under tension; and calculating an untensioned product length L o (t) of the web in the span of the printing press while the web is moving through the printing press under tension as a function of the tensioned repeat length (L 1) and the elastic strain (ε 1), receiving the calculated untensioned product length L o (t) of the web in the span of the printing press while the web is moving through the printing press under tension, comparing L 0 (t) to a previously stored untensioned product length setpoint L setpoint, maintaining closed loop control of the untensioned product length by controlling one or more components on the printing press as a function of said comparing step, and repeating the steps receiving, comparing, maintaining and controlling over time while the printing press is printing on the web, wherein the step of maintaining comprises varying an image velocity of the printing press by varying a rotational velocity of the plate and blanket cylinders.