O-I

O-I stats at a glance

The O-I has 880 hit points , 150mm of frontal hull armor , and a top speed of 25 km/h. Its strongest gun configuration deals 700 damage per shot with 121mm of armor penetration , giving it a theoretical maximum DPM of 1617. The vehicle can equip 2 different gun configurations, allowing for varied playstyles.

Hull & survivability

The front-to-side armor ratio is 2.1:1. This pronounced angling makes the O-I significantly stronger when keeping its front facing the enemy.

Mobility

Forward-to-reverse speed ratio is 2.5:1. Reverse speed is limited, so pre-aim and exposure timing matter more on this vehicle.

Camouflage

Available guns (2)

With the top-tier gun, the O-I can theoretically output up to 1617 damage per minute at sustained fire (shot damage × rounds per minute). Lower-tier guns generally trade DPM for faster reload or better handling — see the full gun table above.

How O-I compares to its peers

There are 24 tier 6 heavy tanks in WoT, including the O-I. Its 880 HP places it in the top 39% for hit points among same-tier heavy tanks (peer average: 851). Frontal hull armor of 150mm ranks in the top 26% for the class (peer average: 136mm). Top forward speed of 25 km/h is faster than 9% of peer vehicles in this tier and class. The strongest gun deals 700 damage per shot, higher than 91% of comparable vehicles. Best penetration of 121mm puts it in the top 87% for armor-piercing capability in its class.

Direct comparisons

• O-I vs M6 — tier 6 heavy tank from USA
• O-I vs Pawlack Tank — tier 6 heavy tank from USA
• O-I vs ARL 44 — tier 6 heavy tank from France
• See full tier 6 heavy tank tier list — all 24 vehicles ranked

Related tier 6 heavy tanks

• A43 BP prototype — UK, premium
• ARL 44 — France
• Char de transition — France, premium
• Churchill St. Gloriana — UK, premium
• Churchill VII — UK
• Churchill Crocodile — UK, premium
• Heavy Tank — USSR
• Heavy Tank No. VI — Japan, premium
• All Japan tanks · Tier 6 premium tanks

Understand the stats

Want a deeper grasp of what these numbers actually mean in battle? Read the glossary:

• What is DPM — the most important offensive metric
• Alpha damage — single-shot damage and what it means for playstyle
• Penetration — and how it interacts with armor angling
• Hull-down position — the king of defensive plays
• View range — how spotting actually works

About this vehicle

Development of the superheavy tank was started after the Battles of Khalkhyn Gol in 1939. The vehicle was designed as a maneuverable fire unit that was unprecedented in scale—its hull alone weighed 100 tons. Only one prototype was built, without a turret and made of construction steel. Trials were discontinued due to the unreliable engine; at the end of 1944, the prototype was scrapped. The 15 cm howitzer was to be mounted on the tank after its assembly.

Frequently asked