What is the company's estimated range for adjusted earnings per share in 2021
d operating margin to be in the range of 23.5% to 24%.
That covers the 2020 guidance. Before discussing our preliminary 2021 targets, we want to remind you that the views we have today are subject to a variety of factors that may manifest themselves over the upcoming months. And hence, are subject to change, so appropriately conservative for the environment in which we are operating. We expect to provide formal 2021 guidance on our 4Q, 2020 call next year. One final note before going further, our preliminary 2021 targets reflect year-over-year growth rates that are based on the midpoint of our updated 2020 guidance for the respective metrics.
So at a high level, we view 2021 currently as a tale of two halves. Specifically we expect H2 will be stronger than H1 provided an economic recovery picks up steam in the back half of the year. Our continued business transition is masking our underlying growth and value creation, due to both license are trading to cloud and global Tier 1 customers ramping up their global footprints over multiple periods. We continue to believe RPO is the best go-forward metric in tracking the progress of our transition.
Our 2021 full-year total revenue range is now expected to be between $585 million to $625 million, representing a 1% to 8% year-over-year growth range. Our target objective is to achieve $605 million, representing 5% growth, excluding our declining license impact year-over-year total revenue growth is 8%.
As you know Q1, 2020 was an all-time record Q1 revenue performance pre-COVID creating a tough comp for Q1 2021. We expect Q1, 2021 total revenue to be down 7% to 9% over Q1, 2020. We expect our H1 total revenue split to be about $292 million with 1% year-over-year growth given the Q1 COVID comp and H2 split to be about $313 million, this is the revenue split with a 9% growth rate.
For software revenue, we are estimating $123 million to $130 million with a midpoint growth of 13%. We are targeting a $108 million to $110 million in cloud growth with midpoint growth of about 40%. Importantly, we expect license revenue to decline, almost 50% in 2021, as customers and prospects choose our cloud solutions. License revenue will be in the $15 million to $20 million range with a midpoint of $17.5 million.
Regarding 2021, RPO our preliminary estimate is between $385 million to $390 million, up about 40% over 2020. And as Eddie mentioned we are off to a very good start in Q4 on strong cloud demand. With the backdrop of COVID, government elections and retail peak season in play and a second full selling quarter of Manhattan Active WM under our belt, this will certainly help us calibrate the camshafts on our RPO entering 2021.
For consulting services, we are targeting $306 million to $334 million with a $320 million midpoint, representing about 5% year-over-year growth. We expect H1 revenue to be down about 3% to 5% year-over-year with Q1 being down 15% against 2020's record services comp. The rate of year-over-year growth in services will be dictated by the pace and cadence of economic recovery for the balance of 2021.
And for maintenance, we are estimating $140 million to $145 million or 4% decline to flat growth year-over-year, as we expect more existing customers to convert to cloud subscriptions. That covers the critical revenue targets.
Our full-year 2021 adjusted earnings per share range is $1.37 to $1.54 with a midpoint of $1.46. H1 to H2 percentage splits will be 45% H1 and 55% H2 for the annual EPS splits. Q1 will be our lowest EPS quarter totaling about 21% of full-year EPS or $0.31. The primary drivers of lower year-over-year earnings per share is related to three major components. First, the continued decline of license revenue. Second, the reversal of prior cost actions we took in April of this year. And third, continued strategic investments in innovation and tooling for cloud ops to execute on the cloud growth we see in front of us.
Adjusted operating margin is expected to decline year-over-year to 20% to 21%, reflecting the operating imperatives covered in our outlook for EPS. Yo
d operating margin to be in the range of 23.5% to 24%.
That covers the 2020 guidance. Before discussing our preliminary 2021 targets, we want to remind you that the views we have today are subject to a variety of factors that may manifest themselves over the upcoming months. And hence, are subject to change, so appropriately conservative for the environment in which we are operating. We expect to provide formal 2021 guidance on our 4Q, 2020 call next year. One final note before going further, our preliminary 2021 targets reflect year-over-year growth rates that are based on the midpoint of our updated 2020 guidance for the respective metrics.
So at a high level, we view 2021 currently as a tale of two halves. Specifically we expect H2 will be stronger than H1 provided an economic recovery picks up steam in the back half of the year. Our continued business transition is masking our underlying growth and value creation, due to both license are trading to cloud and global Tier 1 customers ramping up their global footprints over multiple periods. We continue to believe RPO is the best go-forward metric in tracking the progress of our transition.
Our 2021 full-year total revenue range is now expected to be between $585 million to $625 million, representing a 1% to 8% year-over-year growth range. Our target objective is to achieve $605 million, representing 5% growth, excluding our declining license impact year-over-year total revenue growth is 8%.
As you know Q1, 2020 was an all-time record Q1 revenue performance pre-COVID creating a tough comp for Q1 2021. We expect Q1, 2021 total revenue to be down 7% to 9% over Q1, 2020. We expect our H1 total revenue split to be about $292 million with 1% year-over-year growth given the Q1 COVID comp and H2 split to be about $313 million, this is the revenue split with a 9% growth rate.
 For software revenue, we are estimating $123 million to $130 million with a midpoint growth of 13%. We are targeting a $108 million to $110 million in cloud growth with midpoint growth of about 40%. Importantly, we expect license revenue to decline, almost 50% in 2021, as customers and prospects choose our cloud solutions. License revenue will be in the $15 million to $20 million range with a midpoint of $17.5 million.
Regarding 2021, RPO our preliminary estimate is between $385 million to $390 million, up about 40% over 2020. And as Eddie mentioned we are off to a very good start in Q4 on strong cloud demand. With the backdrop of COVID, government elections and retail peak season in play and a second full selling quarter of Manhattan Active WM under our belt, this will certainly help us calibrate the camshafts on our RPO entering 2021.
For consulting services, we are targeting $306 million to $334 million with a $320 million midpoint, representing about 5% year-over-year growth. We expect H1 revenue to be down about 3% to 5% year-over-year with Q1 being down 15% against 2020's record services comp. The rate of year-over-year growth in services will be dictated by the pace and cadence of economic recovery for the balance of 2021.
And for maintenance, we are estimating $140 million to $145 million or 4% decline to flat growth year-over-year, as we expect more existing customers to convert to cloud subscriptions. That covers the critical revenue targets.
Our full-year 2021 adjusted earnings per share range is $1.37 to $1.54 with a midpoint of $1.46. H1 to H2 percentage splits will be 45% H1 and 55% H2 for the annual EPS splits. Q1 will be our lowest EPS quarter totaling about 21% of full-year EPS or $0.31. The primary drivers of lower year-over-year earnings per share is related to three major components. First, the continued decline of license revenue. Second, the reversal of prior cost actions we took in April of this year. And third, continued strategic investments in innovation and tooling for cloud ops to execute on the cloud growth we see in front of us.
 Adjusted operating margin is expected to decline year-over-year to 20% to 21%, reflecting the operating imperatives covered in our outlook for EPS. Yo