VitaLog vs SteroidPlotter: A Deeper PK Tool in a Full Health App

SteroidPlotter is a long-standing single-purpose AAS PK plotter from the late-2000s bodybuilding forum era. VitaLog includes all of SteroidPlotter's functionality plus ~300 additional compounds, three PK model families, bloodwork trend AI, Vermeulen free-T, cycle tracking, and zero-knowledge encrypted photos.

Last updated: 2026-04-21 · Maintained by the VitaLog team

At a glance

Where SteroidPlotter shines

Credit where due. SteroidPlotter has genuine advantages as a single-purpose tool:

• Instant. Open URL, enter numbers, see curve. No account, no onboarding, no tab menu.
• Familiar. Many bodybuilding-forum discussions link to SteroidPlotter outputs. If you're reading /r/steroids or T-nation threads, you'll see SteroidPlotter screenshots often, a visual vocabulary users already share.
• Lightweight. A single-purpose tool doesn't need a full app shell. For a quick "what does Test E 400mg/week look like" visualization, SteroidPlotter is literally a 30-second answer.
• No telemetry. No accounts means no data collection by design.

If that's what you need and nothing else, SteroidPlotter is fine. VitaLog is not trying to replace its niche for users who are happy with it.

Where SteroidPlotter falls short

The simplicity that's an advantage for casual visualization is a limit for serious use:

• Compound coverage is AAS-centric. No GLP-1 agonists, no peptides, no GH secretagogues, limited SERM/AI coverage. If you're on TRT + semaglutide + BPC-157 (a common stack in 2026), you'll need three different tools.
• Single-compartment only. Testosterone suspension's biphasic kinetics don't match the single-compartment model well. Nandrolone decanoate's slow depot release isn't captured by a simple Bateman curve.
• No variability envelope. The plot shows a single deterministic line, not the P25-P75 band that reflects inter-individual variability in ka, CL, and V. Your real-world response will sit somewhere in the band, not on the line.
• No bloodwork integration. You can plot a curve but not check whether your actual trough measurement matches the modeled trough.
• No cycle tracking. No dose-adherence log, no injection-site rotation, no cycle-phase indicator.
• No PCT planner. Just the decay curve. No SERM dose scheduling.
• No free-T calculation. Can't feed SHBG + albumin and get free T.
• No citations. Kinetic parameters are coded in without source references. For users who want to verify a half-life claim against primary literature, SteroidPlotter doesn't help.

Where VitaLog shines (over SteroidPlotter specifically)

• 330 compounds with per-entry PubMed citations. Most compound entries carry 1-3 PubMed references for published parameters; extrapolated entries (e.g. BPC-157) are flagged as dataQuality: extrapolated.
• Three model families. One-compartment Bateman for most compounds. Two-compartment for testosterone suspension. Biphasic-absorption sum for depot formulations. Metabolite cascade for parent → active-metabolite conversions.
• P25-P75 variability envelope. Every curve shows the interquartile band reflecting inter-individual variability.
• Steady-state metrics computed. Not just Cmax, but Cmax_ss, Cmin_ss, Cavg_ss, AUC_ss, accumulation ratio, days-to-steady-state.
• Full cycle tracking. Daily/weekly/monthly dose schedules, dose-adherence streaks, injection-site rotation, compound interaction alerts.
• Bloodwork trend AI. Import panels; VitaLog flags rising/falling markers, HCT >54% alerts, AST/ALT ratio patterns, age-and-sex-indexed reference ranges.
• Vermeulen free-T. From total T + SHBG + albumin to free T and bioavailable T via the 1999 quadratic.
• PCT planner. Compute the earliest PCT start date from compound terminal half-life + HPG recovery kinetics, pick a SERM dose schedule.
• Full app. Nutrition, workouts, journal, clubs, photos, all in one.

Detailed feature matrix

Who should use which

Stay with SteroidPlotter if:

• You only want to visualize a single AAS-ester curve quickly.
• You don't track bloodwork, peptides, nutrition, workouts, or progress photos.
• You prefer a literal URL-open-get-plot tool with no app shell.
• You rely on the visual vocabulary of forum screenshots and want consistency with how threads illustrate curves.

Use VitaLog if:

• You're on anything beyond pure AAS, GLP-1, peptides, GH secretagogues, SERMs, AIs.
• You want bloodwork tracking integrated with your PK modeling.
• You want cycle tracking, dose adherence, site rotation, PCT planning.
• You want variability envelopes so you see the expected range, not a single line.
• You want published-literature citations for every kinetic parameter.
• You want one unified app instead of five separate single-purpose tools.

Use both:

A common pattern: VitaLog as the primary health-tracking app, SteroidPlotter opened in a browser tab when you're drafting a forum post and need a quick shareable curve visualization in the familiar SteroidPlotter style. Nothing wrong with that, the tools don't conflict.

The honest part

SteroidPlotter has been useful to the bodybuilding community for over a decade and we don't want to pretend it's bad. Its single-compartment simplicity is a genuine asset for the "I just want to see the curve" use case. VitaLog's advantage is depth and integration, not that SteroidPlotter is broken. If you've used SteroidPlotter for years and it works for you, there's no urgency to switch.

Frequently asked questions

What is SteroidPlotter?

SteroidPlotter is a free single-purpose web tool that plots the theoretical serum-concentration curve for injectable testosterone esters (and a small set of other anabolic-androgenic steroids) given dose, ester, and frequency. It uses a simplified one-compartment pharmacokinetic model with published ester half-lives and was one of the earliest widely-used AAS PK visualizers, popular on bodybuilding forums since the late 2000s.

How many compounds does SteroidPlotter support vs VitaLog?

SteroidPlotter supports roughly 25 compounds, primarily testosterone esters (cypionate, enanthate, propionate, phenylpropionate, undecanoate, suspension), nandrolones, boldenone, trenbolone, masteron, primobolan, trestolone, and a handful of orals. VitaLog supports 330 compounds including every SteroidPlotter entry plus SERMs, aromatase inhibitors, GH secretagogues (CJC-1295, ipamorelin, MK-677), GLP-1 receptor agonists (semaglutide, tirzepatide, retatrutide), research peptides (BPC-157, TB-500, MOTS-c, GHK-Cu), and 17-alpha-alkylated orals.

What PK models does each use?

SteroidPlotter uses a single-compartment one-ester model. VitaLog uses three model families: one-compartment Bateman for most compounds, two-compartment distribution for testosterone suspension (biphasic kinetics), and biphasic-absorption sum for depot formulations like nandrolone decanoate. VitaLog also computes P25-P75 variability envelopes using log-normal CV multipliers, plus steady-state metrics (Cmax_ss, Cmin_ss, AUC, accumulation ratio, days-to-steady-state) and Vermeulen free-T conversion.

Does SteroidPlotter track bloodwork?

No. SteroidPlotter is a PK-visualization tool only, no bloodwork tracking, no dose logging, no cycle progression, no injection-site rotation, no compound-interaction alerts. It shows you the theoretical curve and that's it. VitaLog includes all of those workflows plus a bloodwork trend AI that flags rising/falling markers, hematocrit safety alerts, AST/ALT ratio interpretation, and age-and-sex-indexed reference ranges across a 20-test panel.

Does SteroidPlotter simulate PCT?

SteroidPlotter plots the decay curve after cessation so you can visually estimate when serum T drops below a threshold. It does not include a PCT planner that chooses a start date based on terminal half-life + HPG recovery kinetics, nor does it include SERM dose schedules (tamoxifen, clomiphene, raloxifene). VitaLog has a full PCT planner with SERM protocol comparison.

Is SteroidPlotter a better dedicated PK tool?

For casual ester-curve visualization SteroidPlotter is lightweight and familiar, it opens fast, has a simple UX, and is well-known on bodybuilding forums. VitaLog's PK simulator is more thorough (more compounds, more models, variability envelopes, PubMed citations) but lives inside a broader app. If you want a 30-second "what does Test E 400mg/week look like" visualization and nothing else, SteroidPlotter's simplicity is an advantage.

Does VitaLog cite pharmacokinetic data sources?

Yes. Every compound entry in VitaLog's 330-compound database carries 1-3 PubMed PMIDs documenting the kinetic parameters (half-life, Cmax, Tmax, Vd, clearance, protein binding). Extrapolated entries (like BPC-157, where human PK data is sparse) are tagged "dataQuality: extrapolated" and clearly distinguished from compounds with published human data like testosterone cypionate (Behre 2004) or semaglutide (Novo Nordisk label).

What about HalfLife.app and Dosafy?

HalfLife.app and Dosafy are conceptual peers to SteroidPlotter, single-purpose PK visualizers with similar compound coverage (~20-30 entries) and simpler single-compartment models. VitaLog's relationship to them is the same: broader scope (330 compounds, three model families, variability envelopes, integrated bloodwork + cycle tracking) in a full-app context vs. their single-tool simplicity.

Related resources

• Pharmacokinetics explained, the PK framework in plain English
• Peptide dose calculator, 330-compound PK demo
• TRT bloodwork monitoring
• All comparisons