What is a recharge rate?

A recharge rate is the per-unit charge that a core facility sets to recover its operating costs from users. For vivariums, the primary recharge rate is the per-diem: the daily cost per cage. It must be calculated to recover costs without generating profit, per federal cost principles.

What is OMB Uniform Guidance and how does it affect rates?

OMB Uniform Guidance (2 CFR Part 200, formerly Circular A-21) requires that federally funded service centers operate on a break-even basis. Rates must be based on actual costs, applied consistently to all users, and may not exceed the cost of providing the service. Surplus or deficit must be carried forward.

How do I handle different cage types?

Different cage types (standard static, IVC, metabolic, large animal) have different costs due to equipment, consumables, and husbandry time. Use cost multipliers relative to a standard cage. For example, if IVC cages cost 30% more to operate, use a 1.3× multiplier.

What happens if actual census is lower than projected?

Lower census means the same fixed costs are spread over fewer cage-days, resulting in a deficit. The sensitivity analysis shows how rates would need to change at different census levels. Federal guidance allows carrying a deficit or surplus forward to adjust next year's rate.

ToolsConductScience tool

Core FacilityFree in-browser calculator

Recharge Rate Calculator.

Compute per-diem recharge rates by cage type per OMB Uniform Guidance, with break-even census and sensitivity analysis.

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Facility Settings

Projected cage-days/year *

Recovery target (0-1.5) *

Federally funded facility

Annual Operating Costs

Category *

Annual cost ($)

Cage Types

Type *

Fraction (0-1)

Cost multiplier

Required fields

Cost category 1: name is required.
Cage type 1: name is required.
Cage type 1: fraction must be between 0 and 1.
Cage type fractions must sum to 1.0 (currently 0.00).

Warnings

Total operating costs are $0. No per-diem rate can be computed.

When to use

Annual per-diem rate setting for vivarium core facilities
Break-even analysis for new or expanding facilities
Census sensitivity modeling for budget planning
Rate justification for institutional rate review committees

Do not use for

Per-PI billing (use Per-Investigator Billing Calculator)
Grant-level budget estimation (use NIH Animal Cost Budget Calculator)
Space planning (use Vivarium Space Planner)

Pearl

Include equipment depreciation in your cost base even if the equipment is already paid for. Replacement costs are legitimate operating expenses under OMB Uniform Guidance.

Pearl

Run sensitivity analysis at -20% census to see if your facility can absorb a census drop without a mid-year rate increase. This is a common scenario when large studies end.

Pitfall

Do not include costs that are already recovered through other mechanisms (e.g., service charges billed separately). Double-counting inflates per-diem rates.

Pitfall

Federal auditors check that rates are applied consistently. Do not give informal discounts that are not reflected in your published rate structure.

Method

Per OMB Uniform Guidance (2 CFR Part 200): rate = (total operating costs $\times$ recovery target) / (projected cage-days $\times$ weighted cost multiplier). Rates are computed for each cage type using its cost multiplier relative to the standard cage. Break-even is calculated at 100% cost recovery. Sensitivity spans -30% to +30% census in 10% increments.

Validated

Last validated 2026-04-08. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.

How to cite

How to Cite

ConductScience Recharge Rate Calculator (v1.28.0). ConductScience. https://conductscience.com/tools/recharge-rate-calculator

OMB Uniform Guidance, 2 CFR Part 200: Uniform Administrative Requirements, Cost Principles, and Audit Requirements for Federal Awards.

Setting Recharge Rates for Vivarium Core Facilities

Recharge rate calculation follows federal cost principles:

Cost categories: Include all allowable direct costs — personnel (salaries, benefits), supplies (food, bedding, reagents), equipment depreciation, utilities, and consumables. Exclude unallowable costs like entertainment, alcohol, and lobbying.

Cost recovery target: Federally funded facilities must target break-even (100% recovery). Some institutions set rates at 80-90% with the shortfall covered by institutional funds. Never exceed 100% recovery for federal grants.

Cage-type multipliers: Differentiate rates by cage type. Standard static cages are the baseline (1.0×). IVC cages typically cost 1.2-1.5× due to HEPA-filtered air systems. Metabolic cages, large animal housing, and BSL-2/3 containment cages have higher multipliers.

Census sensitivity: Fixed costs (personnel, equipment, utilities) don't change with census, so per-diem rates are highly sensitive to census fluctuation. A 20% census drop can require a 25% rate increase to maintain cost recovery. Build this sensitivity into annual rate reviews.

Annual rate review: OMB requires periodic review. Compare actual costs and cage-days against projections. Carry surplus or deficit forward and adjust next year's rate accordingly.

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Recharge Rate Calculator.

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Facility Settings

Annual Operating Costs

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Setting Recharge Rates for Vivarium Core Facilities

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Per-Investigator Billing Calculator

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