"Lights" debuted at number 111 on the UK Singles Chart for the week ending 18 December 2010, based on digital sales from "Bright Lights". Three months later, during the week ending 12 March 2011, the single entered the top 100 for the first time at number 91. The following week, it rose to number 64, eventually peaking at number 49 in its sixth week on the chart. On the issue dated 20 August 2011, "Lights" debuted at number 85 on the US "Billboard" Hot 100 and at number 89 on the Canadian Hot 100, becoming Goulding's first single to chart in North America. The song re-entered the "Billboard" Hot 100 at number 99 during the week of 14 January 2012. When "Lights" reached number 40 in its 19th week, on the issue dated 12 May, the song attained the third-slowest climb to the top 40 by a female artist, after Norah Jones's "Don't Know Why" and KT Tunstall's "Suddenly I See". In its 29th week, the song made Hot 100 history by achieving the longest climb to the chart's top five not aided by country-to-pop crossover success or multiple releases. The single reached number two in its 33rd chart week, on the issue dated 18 August 2012, and held that position for two consecutive weeks, behind "Call Me Maybe" by Carly Rae Jepsen and "Whistle" by Flo Rida, respectively, making it Goulding's highest-peaking single on the chart to date. "Lights" ascended to number one on the Radio Songs chart on the issue dated 25 August 2012, making Goulding the first female solo artist to send a debut Radio Songs entry to number one since Adele led the list in 2011 and 2012 with her singles "Rolling in the Deep", "Someone Like You" and "Set Fire to the Rain". The song also topped the Mainstream Top 40 during the same week, matching Pink's "U + Ur Hand" (23 weeks, 2006–2007) for the longest climb to number one by a woman in the chart's almost-20-year history. The single also made a re-entry on the Canadian Hot 100 at number 87 on 28 April 2012, eventually peaking at number seven on 22 September. In late December 2012, "Lights" spent its 52nd week on the Hot 100 at number 43, becoming the 30th song in the chart's history to spend a year on the tally.