When to use
- Scaling GLP study cohorts under FDA, OECD, EPA, or ICH requirements
- Planning satellite/TK and recovery group sizes
- Estimating total animal orders with replacement reserves
- Generating ordering schedules for animal procurement
ToolsConductScience tool
Biotech / PharmaFree in-browser calculator
GLP Study Cohort Scaler.
Compute regulatory-minimum group sizes for GLP preclinical studies. Supports FDA, OECD, EPA, and ICH frameworks with satellite, recovery, and replacement reserves.
PrivateData stays in your browser
LiveNo sign-up required
Validated2026-04-08
CitableMethods and citation included
Calculator
Results update in placeTry it out
Load example GLP cohort scaler data to see the full workflow
Study Design
Dose Groups
Required fields
- Dose group 1: name is required.
- Dose group 1: dose level is required.
Do not use for
- Non-GLP exploratory or pilot studies (use general sample size calculator)
- Clinical trial cohort sizing (use clinical sample size tools)
- Colony breeding planning (use Colony Expansion Forecaster)
Pearl
Always include a concurrent vehicle control group. Regulatory reviewers expect concurrent controls; historical controls alone are insufficient for GLP submissions.
Pearl
Order replacement animals from the same supplier lot and age-match them. Replacements from a different source or age cohort can introduce variability that confounds your study.
Pitfall
Do not assume the same group size applies across frameworks. OECD TG 407 (subacute) requires 5/sex/group while FDA Redbook recommends 10/sex/group for the same study duration.
Pitfall
Satellite/TK animals share the same dosing regimen but have different endpoints. Ensure your protocol clearly distinguishes main-study animals from TK animals at the group-assignment level.
1
Method
The calculator applies regulatory-minimum group sizes from FDA Redbook 2000, OECD Test Guidelines, EPA OPPTS, and ICH S-series based on selected study type and framework. For each dose group (plus vehicle control if selected), it computes: main study animals per sex, satellite/TK animals per sex, recovery animals per sex, and replacement reserves as a percentage of all study animals. The ordering schedule is generated backwards from study initiation.
2
Validated
Last validated 2026-04-08. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.
3
How to cite
How to Cite
ConductScience GLP Study Cohort Scaler (v1.25.0). ConductScience. https://conductscience.com/tools/glp-cohort-scaler
FDA Redbook 2000: Guidance for Toxicological Testing. U.S. Food and Drug Administration.
OECD Guidelines for the Testing of Chemicals, Section 4: Health Effects.
ICH S3A: Note for Guidance on Toxicokinetics (1994).
Designing GLP-Compliant Preclinical Cohorts
Good Laboratory Practice (GLP) preclinical studies have specific requirements for group sizes that vary by study type and regulatory authority:
Regulatory minimums: The minimum number of animals per sex per dose group is set by guidelines such as FDA Redbook 2000, OECD Test Guidelines (407, 408, 451–453), EPA OPPTS, and ICH S-series. Using fewer animals than the minimum can invalidate the study for regulatory submission.
Satellite/TK groups: For repeat-dose studies, toxicokinetic (TK) satellite animals provide pharmacokinetic data (Cmax, AUC) without disturbing the main toxicology cohort. ICH S3A recommends TK sampling at multiple time points. Satellite groups are typically 3–5 animals per sex per group.
Recovery groups: Recovery animals continue through a treatment-free period (usually 2–4 weeks for subchronic, 4 weeks for chronic) to assess reversibility of findings. This is increasingly expected by FDA and EMA for novel therapeutics.
Replacement reserves: Order 10–15% extra animals to account for losses during acclimatization, health screening failures, or early-study attrition. Replacements must be from the same supplier lot and age-matched.
Combination studies (OECD TG 453): Combined chronic/carcinogenicity studies use 50/sex/group for the carcinogenicity arm and 20/sex/group for the chronic arm, sharing the vehicle control.
Frequently asked
325
Free tools
1,200+
Institutions
100%
Client-side
0
Uploads required
Next steps
App
ConductColony
Track GLP cohorts with audit-ready records. ConductColony links cohort plans to live census, randomization, and dosing logs — all under 21 CFR Part 11 electronic signature.
Open app App3Rs Justification Builder
Build a 3Rs justification statement for your IACUC protocol
Open app AppIACUC Budget Estimator
Estimate per-diem and service costs for your animal protocol
Open app AppGLP Audit Checklist
ALCOA+ data integrity checklist for GLP studies
Open app