Polls conducted before the referendum show most people support the draft charter, as the voting ended at 4pm on Sunday.
The Nida poll conducted last week and released on Sunday after the end of the referendum vote showed most people supported the draft charter.
The Nida poll by the National Institute of Development Administration showed overwhelming support for the charter, with 76.87% saying they would accept the draft and only 18.68% against it.
- Photo gallery: Charter referendum
The poll, which was released shortly after all polling units closed at 4pm, surveyed 5,849 samples from Tuesday to Saturday.
Bangkok Poll by Bangkok University, which was released after 4pm, also showed that 57.3% backed the draft, while 42.7% voted against it.
The Bangkok Poll asked 9,564 people across the country from July 5 to Wednesday.
People flocked nationwide polling units to cast ballots for the charter referendum, which ended at 4pm on Sunday.
Election Commission (EC) chairman Supachai Somcharoen said after all units were closed that an unofficial result could be announced at 9pm. The official result is expected on Wednesday if there are no complaints lodged to the EC.
He hoped at all parties would accept to the result of the referendum.
Many polling stations witnessed long lines of voters checking their names, with the future of the draft backed by the National Council for Peace and Order and government at stake.
The Pheu Thai Party and Democrat Party leader Abhisit Vejjajiva had made clear their position to it.
All key figures including Prime Minister Prayut Chan-o-cha, Deputy Prime Minister Prawit Wongsuwon, Privy Council president Prem Tinsulanonda, Mr Abhisit and former prime minister Yingluck Shinawatra went to their polling stations soon after voting opened.
The EC chairman said the voting largely went smoothly but some units including the one at Bang Na district found a student and anti-coup activist was arrested for tearing his ballot slip.
