Ronald dela Rosa was speaking at a senate hearing into the sharp rise in deaths since Rodrigo Duterte became president.
He said police operations had killed about 750 people, but the other deaths were still being investigated.
Mr Duterte won the presidency with his hard-line policy to eradicate drugs.
He has previously urged citizens to shoot and kill drug dealers who resisted arrest, and reiterated that the killings of drug suspects were lawful if the police acted in self-defence.
He also threatened to "separate" from the UN after it called his war on drugs a crime under international law.
The US has said it is "deeply concerned" by the increase in drug-related killings.
The senate joint inquiry is being conducted by Senator Leila de Lima, who has called on authorities to explain the "unprecedented" rise in deaths.
It is also hearing from the relatives of some of those killed.
The family members of some of those killed are getting the chance to tell their stories to the inquiry.
Wearing dark glasses and draped in a shawl, Harra Besorio said policemen raided her home in Pasay City without a warrant and stripped her infant daughter to check for drugs.
Her partner, who she admitted was a small-time dealer, and his father were beaten up in front of them, she told the inquiry on Monday. They were later taken to a police station and allegedly killed there.
The two police officers accused claimed an attempt had been made to grab one of their guns, but this was refuted by the Philippines Commission on Human Rights.
It said they had been badly injured and were shot three times. The two officers have been charged with murder.
Mr dela Rosa told the inquiry on Tuesday that a total of 1,916 deaths had been recorded during the crackdown, 756 of which were during police operations.
He said the number had gone up even since he gave evidence on Monday, where he gave a figure of 1,800 deaths.
"Not all deaths under investigations are drug-related," he told news agency Reuters, saying about 40 killings were due to robbery or personal disputes.
However, Mr dela Rosa said there was no declared policy to kill drug users and pushers, saying police were "not butchers".
The police director-general also added that about 300 police officers were suspected to be involved in the drugs trade, warning that they would be charged and removed from their positions if found guilty.
Nearly 700,000 drug users and peddlers have turned themselves in since the launch of the campaign, Mr dela Rosa said.
He also said that there was a decrease in overall crime, though the number of homicides and murders had increased.
On Monday, Mr dela Rosa told the inquiry: "I admit many are dying but our campaign, now, we have the momentum."
Senator Frank Drilon told Reuters that the number of deaths was "alarming" and had "a chilling effect".
In his previous role as mayor of Davao, Mr Duterte built a reputation for blunt speaking and supporting the extrajudicial killings of suspected criminals.
Crime rates in Davao decreased while he was in office, though human rights groups estimate than more than 1,000 people were killed with no legal process.
The head of the Philippines police has said more than 1,900 people have been killed during a crackdown on illegal drugs in the past seven weeks.