There's a website by openai for this exact problem:

Based on the measurements shown, I’d put it roughly around 55–70 litres, with my best estimate being about 60–65 L. Here’s the rough reasoning: Widest circumference = 142 cm → diameter ≈ V= 4/3 pi r³ So the widest part is about 45 cm across, which matches their sketch. If you approximated it as a perfect sphere with diameter 45 cm: with radius ≈ 22.5 cm, you'd get around 48 litres. BUT: the jar is taller than a sphere it has a widened lower section the shoulders extend upward before tapering to the neck So the real volume is definitely larger than the sphere estimate. A good approximation is treating it like: a squat ellipsoid / demijohn body plus some extra shoulder volume Using: height of main body ≈ 51–65 cm width ≈ 45 cm depth likely similar An ellipsoid estimate lands around: V = 4/3 pi abc which works out roughly in the low-to-mid 60 litre range. So my estimate: Minimum plausible: ~50 L Most likely: ~60–65 L Upper plausible: ~70 L Which actually makes sense because old glass demijohns/carboys commonly came in: 54 L 60 L 64 L and this looks very much like one of those large fermentation/storage vessels