Preferably, You need to allow three-5h of transit time in Johannesburg, so that you've got sufficient the perfect time to catch your connecting flight. Transiting in Johannesburg is rather easy; simply just Stick to the indications for ‘Worldwide Transit’. The flight from Johannesburg to Harare usually takes about 1h 30m. https://www.theluxurybooking.co.uk/flights-to-zimbabwe-from-london/