Leaked Documents Disclose Russian and Ukrainian Casualties

The data isn't fully authenticated but sounds very plausible.

According to an assessment collated by the U.S. Defense Intelligence Agency, Russia has suffered 189,500-223,000 total casualties, including 35,500-43,000 killed in action and 154,000-180,000 wounded.

Ukraine has suffered 124,500-131,000 total casualties, including 15,500-17,500 killed in action and 109,000-113,500 wounded in action, according to the document entitled "Russia/Ukraine - Assessed Combat Sustainability and Attrition."

Via Reuters (yesterday).