It's about as big as a Concrete Mixer Truck.
(a.k.a. cement mixer, a.k.a. cement mixer truck, a.k.a. cement transport truck, a.k.a. concrete mixer, a.k.a. concrete transport truck, a.k.a. in-transit mixer)(standard size; drum capacity)
A concrete mixer truck has a drum volume of up to 95 barrels. Concrete mixer trucks can be in transit for about 90 minutes before the concrete dries — if the concrete dries while in the drum, jackhammers or even dynamite must be used to remove it.
It's about sixteen times as big as a Hot Tub.
In other words, 99 barrels is 15.90 times the size of a Hot Tub, and the size of a Hot Tub is 0.0629 times that amount.(for Lifesmart Rock Solid Simplicity Plug and Play 4 Person Spa With 12 Jets) (a.k.a. Spa, a.k.a. Jacuzzi, a.k.a. Whirlpool) (Advertised Capacity)
An average, four-person hot tub holds 6.220 barrels of water. Modern hot tubs became popular outside of Japan starting in about 1940.
It's about 70 times as big as a Bathtub.
In other words, 99 barrels is 72 times the size of a Bathtub, and the size of a Bathtub is 0.014 times that amount.(a.k.a. bath, a.k.a. tub) (for Bootz Industries Aloha 5 ft. Left Hand Drain Soaking Tub)
The capacity of a typical bathtub is 1.40 barrels. Historically, bathtubs have been made of various materials including marble, terracotta, silver, gold, and iron but the size and shape of the tubs has changed little in their 7,000 year history.
It's about 150 times as big as a Car Gas Tank.
In other words, 99 barrels is 151 times the size of a Car Gas Tank, and the size of a Car Gas Tank is 0.00662 times that amount.(for 2009 Ford Taurus)
A car gas tank (for example, that of a 2009 Ford Taurus) holds 0.6550 barrels of gas. In contrast, the Curved Dash Oldsmobile — the first mass-produced car — had a fuel capacity of just 0.1730 barrels.
It's about one-two-hundredth as big as a Hot Air Balloon.
In other words, 99 barrels is 0.0052 times the size of a Hot Air Balloon, and the size of a Hot Air Balloon is 190 times that amount.(four-person capacity; envelope volume; average)
The average volume of a hot air balloon sufficient to lift four adults is 19,000 barrels. Typically made of nylon or dacron, a balloon envelope of this size typically weighs just 88 kg (190 lbs).
It's about 200 times as big as a Beer Keg.
In other words, 99 barrels is 195 times the size of a Beer Keg, and the size of a Beer Keg is 0.00513 times that amount.(Half barrel; maximum capacity)
The most common keg size sold by US beer sellers is a half-barrel type with a volume of 0.5080 barrels. This type of keg contains the equivalent of 165 0.00307 barrels cans of beer.
It's about one-two-hundredth as big as an Olympic Swimming Pool.
In other words, 99 barrels is 0.0046 times the size of an Olympic Swimming Pool, and the size of an Olympic Swimming Pool is 220 times that amount.(FINA regulation; (minimum capacity)
According to the Fédération Internationale de Natation (FINA), a swimming pool for Olympic and world championship events must measure 50 m by 25 m with a depth of at least 2 m for a total volume of 22,000 barrels. A pool of this size was to be used in Olympic time trials in New Jersey in early 2008, but its component pieces were stolen from a warehouse, likely to be sold for scrap metal.