Usually, it's no joke, but the agony of most event organisers.

But it seems there's something those in the capital will buy tickets early for, and that's comedy.

The Canberra Comedy Festival is back this week, returning for its sixth year from March 19-26.

Held across stages at Canberra Theatre, The Street Theatre, Civic Pub and the ANU, this year's lineup includes international acts Rich Hall, Stephen K Amos, Urzila Carlson, Arj Barker and Ross Noble, alongside Aussies like Nazeem Hussain, Dave Hughes, Cal Wilson, Joel Creasy, Nath Valvo and Becky Lucas.

Around 18,000 tickets went on sale for the festival, and the Canberra Comedy Festival's Dave Graham said that the event was almost 70 per cent sold out at the start of the week.

"A bunch of shows are completely sold out, like the opening gala has been sold out for ages and people are crawling over broken glass to get tickets. We put it on sale earlier and earlier each year and it sells out sooner," he said.

"It's a fantastic feeling that you have such a big week of comedy because a lot of [touring artists] don't come to Canberra because, 'no one will buy tickets in time' - that late ticket buying scares them. So it's good to be the big show in town."

The festival was launched during Canberra's centenary year in 2013, and Mr Graham said the capital's comedy scene has grown significantly since then.

"It used to be we begged them to come to us and now they ask to come to us," he said.

Canberra comedian Chris Ryan, who performed at the festival's opening gala on Tuesday night and also has a show on Thursday night at the ANU School of Music, agrees that Canberra has firmly secured itself on the Australian comedy map.

"We're on the national touring circuit now and we've got a name for comedy in Canberra and it's just gonna get bigger I think. I just hope the audiences come along with that growth. There's heaps more comedians but I just hope we continue to see new faces at comedy gigs, live gigs, that's the most important part of all of this for performers, we need an audience," she said.

"But the team that puts this festival together has done an incredible job in building it, getting Canberrans to embrace it, getting participation from business, from government, all walks of life, volunteers. It's become bigger than ever and it's a credit to them but also a credit to the canberra community to get out of the house and participate."

A new addition to the festival this year is Festival Square, an alfresco bar in Civic Square out the front of Canberra Theatre with fake grass, tables, food vans plus DJs, trivia and live music during the week. Entry is free and the square is open from 5pm every day during the festival.

Full program and tickets at canberracomedyfestival.com.au.