Early estimates put the crowds at more than 20,000, with ticket returns and exhibition attendances throughout the festival suggesting an overall audience figure of around 83,000.
That's a significant increase on the 2016 festival audience figure of 67,000 and has reinforced organiser South Kesteven District Council's decision, announced by Deputy Leader Cllr Kelham Cooke, to make it a permanent fixture.
More than 20,000 people saw Luke Jerram's Museum of the Moon exhibit, with a long queue on Saturday night prompting St Wulfram's Church to extend its Sunday opening times until 9pm.
Top level talks on science, heritage and botany - many of them sell-outs - drew almost 9,000 appreciative attendees from all over the UK and 2,000 people got their world turned upside down in the Anti Grav Box in Abbey Gardens - back by popular demand.
Grantham Museum's Science Salon, with its interactive globe tracing Endeavour's voyages and a flower show, welcomed 6,000 people - as many as the museum usually gets all year.
Gravity's five days of festival colour and entertainment, all inspired by Sir Isaac Newton's local links, have been claimed as an outstanding success by SKDC.
"I am delighted to see what a success our fourth Gravity Fields Festival has proved to be," said The Council Leader, Cllr Matthew Lee, whose Cabinet portfolio includes arts and culture.
"The sheer range of entertainment has been spectacular. Taking inspiration from Sir Isaac Newton, our festival curator and Arts Centre team devised the most amazing programme to appeal to all ages.
"We had serious and fun science, art, heritage, comedy, school events, free exhibitions and the unforgettable outdoor spectacular on Saturday evening.
"Special thanks must go to all our volunteers, without whom the festival simply could not happen, the community groups and schools who got involved and local businesses who supported us with in-kind contributions."
"Full houses for talks in both Grantham and Newton's home at Woolsthorpe illustrate its science appeal to a growing audience and we are delighted to announce that Gravity Fields Festival is now a permanent fixture in our district calendar."
Saturday's entertainment included dare-devil high-wire acrobatics from Gorilla Circus in the Market Place to replicate the 'rigging' on HMS Endeavour, whose voyage 250 years ago prompted the festival theme of 'Voyages of Discovery'.
Never before has a ship 'sailed' up Grantham High Street, but Saturday night's audiences were treated to the sight of a carnival replica of Endeavour with performances along the route to show its battle with the elements.
St Peter's Hill was ablaze with a Garden of Light from French lighting specialists TILT, the perfect setting for a spectacular fireworks show wrapping up the evening.
Following the sell-out performance from Professor Brian Cox the previous weekend, the festival's science theme continued on Wednesday with 1,800 youngsters and families flocking back to the Meres Leisure Centre for The Big Space Show on Wednesday.
Helen Sharman, the UK's first astronaut, charmed her audience at a Saturday's Sun and Space Show alongside Professor Lucie Green and BBC astronaut competition winner Dr Suzie Imber. Dr Sharman's appearance was one of very few invitations she accepted this year from the hundreds received.
Festival patron Professor Valerie Cox, opening the science salon at Grantham Museum, repeated her belief that Gravity Fields Festival is one of the best in the country.
"There are three reasons why I say that," she said. "One is the amazing level of community and schools' involvement, and a second is the fact that Grantham now has so much going for it, despite once being labelled as the UK's most boring town.
"The third reason is that we are very lucky in the high calibre of the people organising it, and I think that bodes very well for the future."
Picture 1: Huge crowds gathered to see a replica of HMS Endeavour in Grantham Market Place before it 'sailed' along town centre streets.
Picture 2: Luke Jerram's Museum of the Moon exhibit in St Wulfram's Church was so popular the Sunday opening times were extended.
Picture 3: The UK's first astronaut, Helen Sharman, meets audience members after a Sun and Space Show.
Picture 4: Festival patron, Professor Valerie Cox, with Harry Cliff at the opening of the science salon in Grantham Museum.
Picture 5: St Peter's Hill was transformed into a Garden of Light.
Picture 6: Saturday night closed with a spectacular fireworks display.
For general media enquiries: Email the SKDC communications team at firstname.lastname@example.org or call 01476 406498 or 406440.