How does the cost of immigration detention compare to federal prison per inmate per day?
Executive summary
Available sources show ICE detention costs per detainee reported in recent coverage at roughly $159–$190 per person per day, with some outlets citing about $165 per day; by contrast, the Bureau of Prisons’ (BOP) annual budget in 2025 was reported at about $8.3–$8.6 billion, which is the fiscal-frame comparator used by advocates arguing ICE detention funding now rivals or exceeds the entire federal prison system [1] [2] [3] [4] [5].
1. How reporters and advocates measure “per inmate per day”
Journalists and advocacy groups most often compute an ICE daily per-detainee figure by dividing custody operations or contract payments by average daily population; recent articles and briefs put that number in the roughly $159–$190 range — for example, a 2018 Forum analysis estimated about $159/day and more recent reporting cites figures around $165–$190/day for ICE detention [1] [3] [2]. Those per-day numbers reflect ICE detention contracts and custody budgets rather than the detailed program-level accounting the Government Accountability Office has warned is unreliable [6].
2. The federal prison spending benchmark
Advocates use the Federal Bureau of Prisons’ budget as the natural comparator to immigration detention. Sources cite the BOP’s budget in 2025 at about $8.3–$8.6 billion — figures employed to argue that proposed ICE detention funding would match or exceed BOP spending [4] [5]. Those comparisons rest on total agency budgets, not per-inmate per-day line items, and so they mix two different metrics: aggregate budget size versus daily cost per person [4] [5].
3. Simple math and why apples-to-apples is tricky
Putting the figures side‑by‑side requires choices. If ICE pays roughly $165–$190 per detainee per day, that translates to about $60,225–$69,350 per person per year if held 365 days — but detention populations turn over rapidly, and average lengths of stay vary, so annualized per-person figures are unstable [3] [2] [1]. Meanwhile, BOP’s $8.3–$8.6 billion budget covers roughly 155,000+ inmates (per sources referencing prison population in context), producing a different per-inmate cost profile not directly documented in the provided reporting [7] [4]. Available sources do not present a single authoritative, audited per-BOP-inmate-per-day number within the provided set; that specific metric is not found in current reporting.
4. What recent legislation changes the scale
Multiple sources document a major 2025 spending package that dramatically raised ICE detention appropriations — figures cited include $45 billion for new detention construction and an additional $11.25 billion per year for ICE detention in some summaries — and commentators note that these amounts would make ICE detention funding comparable to or larger than the entire federal prison budget [8] [7] [4] [5]. Analysts and advocacy groups warn that such appropriations could push ICE’s detention budget to be 50–62 percent larger than the BOP budget, depending on the comparison used [8] [5].
5. Who benefits from the arithmetic — and why it matters
Coverage from the Brennan Center and Marketplace frames the budget surge as a windfall for private prison firms that run most ICE detention beds; Marketplace reports ICE paying roughly $165/day under contracts, and the Brennan Center highlights that nearly 90 percent of ICE detainees are held in for-profit facilities, a fact that shapes lobbying and budget outcomes [3] [9]. These institutional incentives matter: expanding detention capacity creates revenue opportunities that critics say influence policy choices [9].
6. Limitations in the public numbers and competing viewpoints
Reporting and advocacy analyses differ on methodology. The GAO has cautioned ICE’s costing models are unreliable, and several advocacy briefs rely on aggregate appropriations divided by capacity to estimate per-day costs — a method sensitive to assumptions about beds, occupancy, and whether construction and deportation operations are included [6] [7] [4]. Proponents of expansion emphasize operational needs and national security; critics emphasize cost, human rights, and that detention does not demonstrably deter migration — both perspectives appear in the reporting [10] [9].
7. What readers should take away
Available sources consistently report ICE detention per-detainee-day in the roughly $159–$190 range and show proposals that would drive ICE detention spending to be comparable with, or exceed, the Bureau of Prisons’ entire annual budget [1] [3] [4] [5]. However, an exact, audited comparison of “ICE detention cost per detainee per day” versus “BOP cost per inmate per day” is not presented in the provided reporting; the numbers cited reflect different accounting choices and policy arguments rather than a single standardized cost study [6]. Readers should treat headline comparisons as policy assertions built on specific assumptions and consult audited GAO or agency budget breakdowns for an apples-to-apples per-inmate-per-day figure — those detailed audit numbers are not included in the current reporting set.