Court-martial Judge Colonel Denise Lind convicted Manning, 25, last week on 19 criminal counts, including espionage and theft, for providing more than 700,000 secret files to WikiLeaks in the largest unauthorized release of secret data in US history.
Lind ruled that some counts resulted from the same offenses and should be merged to avoid "an unreasonable multiplication of charges."
Manning's attorneys had objected that the prosecution was overreaching in seeking separate sentences for all the espionage charges. His lawyers acknowledged he had downloaded files on different days, but said he grouped many of them into single files before transmitting them in 2010 to WikiLeaks, a pro-transparency website.
For most of the espionage charges resulting from the transmissions, "there is no evidence of prosecutorial overreaching," Lind said.
Access to classified information remains a sensitive subject after Edward Snowden, a US intelligence contractor, this summer revealed the super-secret National Security Agency program to collect phone and Internet records.
Manning, a low-level intelligence analyst described during the trial as an Internet expert, faces the prospect of decades of prison monotony without online access, likely at the US Disciplinary Barracks at Fort Leavenworth, Kansas.
The sentencing phase began last week and is expected to last at least until Friday. Lind ruled during preliminary hearings that the sentence would be trimmed by 112 days because Manning was mistreated following his arrest in Iraq in May 2010.
Manning was found not guilty of the most serious charge of aiding the enemy, and his lawyers have portrayed him as naive, but well intentioned. They argue his aim was to provoke a broader debate on US military policy, not to harm anyone.
The judge also ruled she would not allow the prosecution's "aggravation evidence" to be considered in sentencing unless it could be shown to be "a direct and immediate result" of information he gave to WikiLeaks. Aggravation evidence refers to problems that worsened because of a criminal offense.
Examples of evidence the judge said she would not allow include testimony last week from a retired army brigadier general that the Taliban apparently used WikiLeaks information to track down an enemy in Afghanistan and kill him.
In a sign of the international furore the Manning case has generated, a play about the slightly built, gay soldier won a newly created drama prize at Britain's oldest literary awards.
