Kevin March, SVP & Chief Financial Officer
I will probably add one more thing in there too. Our strategy that we discussed for a couple of years now of buying our capacity ahead of our needs and always have an ample capacity, quite frankly gives our customers, new and old, increased confidence that we have adequate capacity to meet their demand requirement. And they see us consistently maintaining short lead times. And for that system another element that helps us to be able to win market share versus some of the other competitors we are up against.
Dave Pahl VP, Head of Investor Relations
Okay thanks John, we go to the next caller please.
Operator
We go next to Harlan Sur, JPMorgan
Harlan Sur, JPMorgan
Good afternoon and great job on the quarterly execution. Thank you taking us to the OpEx step-up here in Q1. Now with most of the embedded in Japan restructuring kind of behind you, but continued discipline on the team’s part, how should we think about the OpEx trend beyond the first quarter? I think, Kevin, I heard you mentioned your embedded OpEx kind of holding flattish, but how should we think about the overall business beyond Q1?
Kevin March, SVP & Chief Financial Officer
I think the best way to think about that is — we discussed I think it was back in 2011 that on average we would expect our OpEx to run between 20% and 30% of revenue. So like in a weak market it might be at the 30% level and stronger markets it would be in the 20% level. We are in a pretty good. We are performing quite well in the markets right now and so you are seeing that OpEx come down. In fact most recently, the second half of 2014 we were running around 23% of revenue. So I would say that you would want to model us in the lower half of that range, as you try to think of how much our OpEx spend will be in 2015.
Dave Pahl VP, Head of Investor Relations
Do you have follow on Harlun?
Harlan Sur, JPMorgan
Yes thank you for that. Your thoughts directionally on utilization levels here in Q1 given the seasonality in your business? I would assume that it is down again given the book-to-bill ratio and revenue guidance for Q1. Is that also how we should not think directionally about gross margins as well?
Kevin March, SVP & Chief Financial Officer
I think the way you need to think about utilizations is first by definition, because we buy capacity ahead of time, we will be definition be operating under in an under-utilized environment versus our maximum capacity, theoretical capacity. But that aside, because manufacturing cycle times, the materials that we are starting in the first quarter, especially as we move into the second month of the first quarter, really is destined for second quarter shipment. So your utilization tends to pre-stead the quarter you are moving into as to what your expectations are. And as the second quarter for the last three, four, five years now, and normally for us is a growth quarter compared to the first quarter, we will adjust our factory loadings accordingly to our expectation to second quarter revenue expectations.
Dave Pahl VP, Head of Investor Relations
Okay. Thank you Harlun and we’ll go to the next caller please.
