Testosterone Cypionate vs Propionate Dosing

Last updated: June 2026

Testosterone cypionate and propionate are the same hormone on two different release timers: cypionate has a long ester (half-life roughly 8 days) so it is injected about once a week, while propionate has a short ester (half-life under one day) and is injected every other day or daily. They are not milligram-for-milligram equivalent — the longer ester carries more inert weight, so 100 mg of cypionate delivers slightly less actual testosterone than 100 mg of propionate.

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TL;DR — key takeaways

Same drug, different timer. Both are testosterone in oil; only the attached ester — cypionate (8 carbons) vs propionate (3 carbons) — differs, and that controls how fast it releases.
Frequency follows half-life. Cypionate once weekly (or split twice weekly); propionate every other day or daily to avoid peaks and crashes.
Weight fraction differs. About 70% of a cypionate molecule is testosterone vs ~84% for propionate, so equal milligram labels are not equal testosterone.
Units follow concentration, not ester. Whether you draw 25 or 70 units depends on the mg/mL on your vial — identical maths for either ester.
Availability differs. Cypionate is a stocked FDA-labelled product in the US; propionate is far less common and often compounded.

Why the two esters behave so differently

Injectable testosterone is a prodrug. The hormone is esterified at its 17-beta hydroxyl group with a fatty-acid chain, dissolved in oil, and deposited as a depot in muscle or fat. Enzymes then cleave the ester to free active testosterone. The longer and more fat-loving (hydrophobic) the chain, the slower the drug leaves that depot — which is the whole reason ester choice changes your schedule.

Propionate is a 3-carbon chain with an intramuscular elimination half-life of roughly 0.8 days. Cypionate's 8-carbon chain stretches that to around 8 days. Practically, propionate is dosed two to three times per week (often every other day), while cypionate — like its close cousin enanthate — is dosed once every one to two weeks. A shorter ester means steadier levels are possible but only if you inject often; a longer ester is convenient but produces a bigger peak-to-trough swing across the week.

Side-by-side: the two esters at a glance

Property	Cypionate	Propionate
Ester chain	8-carbon (long)	3-carbon (short)
Approx. IM half-life	~8 days	~0.8 days
Typical frequency	Weekly or twice weekly	Every other day or daily
Testosterone by weight	~70%	~84%
Time to steady state	~3–5 weeks	~1 week
Peak-to-trough swing	Larger across a week	Smaller if dosed often
US availability	FDA-labelled, stocked	Uncommon, often compounded

Half-life figures reflect intramuscular oil-depot pharmacokinetics summarised in andrology references; the percentages are the testosterone fraction of each ester molecule. Your prescriber sets the actual dose, frequency, and route — this page is the arithmetic behind it, not a protocol.

Serum levels: the shape of each schedule

The diagram below contrasts a once-weekly cypionate injection with every-other-day propionate. Same average exposure, very different ride: the long ester rises and falls in one broad wave per week, while the short ester traces small, frequent ripples.

Matching a dose across esters (the weight trick)

Because the ester adds inert mass, equal milligram labels are not equal testosterone. To compare them honestly, multiply the labelled milligrams by the testosterone fraction of that ester.

Worked example 1 — cypionate weight fraction

You inject 100 mg of testosterone cypionate. Cypionate is about 70% testosterone by weight.

100 mg × 0.70 = ~70 mg of actual testosterone delivered.

Worked example 2 — propionate weight fraction

You inject 100 mg of testosterone propionate. Propionate is about 84% testosterone by weight.

100 mg × 0.84 = ~84 mg of actual testosterone — about 20% more hormone per labelled milligram than cypionate.

Worked example 3 — equal-testosterone weekly target

A common cypionate dose is 100 mg/week → ~70 mg testosterone. To match that with propionate: 70 ÷ 0.84 = ~83 mg propionate per week.

Split every other day (about 3.5 doses/week): 83 ÷ 3.5 = ~24 mg per injection. This is illustrative arithmetic, not a prescription.

Turning each dose into syringe units

The milligram dose is not what you read on the barrel — you read units, and a U-100 insulin syringe holds 100 units per 1 mL. The conversion is identical for either ester: divide your dose by the vial concentration (mg/mL) to get mL, then multiply by 100 for units.

Worked example 4 — cypionate, weekly

Vial labelled 200 mg/mL, dose 100 mg/week.

100 ÷ 200 = 0.5 mL. 0.5 × 100 = 50 units on a U-100 syringe.

Worked example 5 — same cypionate dose, split twice weekly

The same 100 mg/week, halved to 50 mg twice weekly from a 200 mg/mL vial.

50 ÷ 200 = 0.25 mL. 0.25 × 100 = 25 units per injection — smaller peaks, same weekly total.

Worked example 6 — propionate, every other day

Vial labelled 100 mg/mL, dose 25 mg every other day.

25 ÷ 100 = 0.25 mL. 0.25 × 100 = 25 units. Note the same 25 units is a different mg dose than example 5 because the vial strength differs.

Dose-to-units reference chart

Testosterone dose per injection shown as units on a U-100 syringe at the two most common vial strengths. Always confirm against your own vial label.

Dose	At 100 mg/mL	At 200 mg/mL
25 mg	25 units	12.5 units
50 mg	50 units	25 units
70 mg	70 units	35 units
100 mg	100 units (1 mL)	50 units
140 mg	— (over 1 mL)	70 units
200 mg	— (over 1 mL)	100 units

Notice that any dose needing more than 1 mL on a 100 mg/mL vial overflows a standard 1 mL syringe, which is one reason 200 mg/mL is the common TRT strength for larger doses.

How this is calculated

Every number here rests on three facts: a U-100 syringe holds 100 units per mL, concentration is dose-per-volume, and each ester is a fixed percentage testosterone by molecular weight (cypionate ~70%, propionate ~84%, from the molecular masses of the ester versus free testosterone). There is no drug-specific fudge factor — the unit maths is identical for either ester, and only the weight fraction and injection frequency change. This is an education and arithmetic tool, not medical advice, and no part of it has been clinically reviewed; your prescriber sets the dose, ester, and schedule that are right for you.

Frequently asked questions

Is propionate stronger than cypionate?

Per labelled milligram, propionate delivers a bit more actual testosterone (~84% vs ~70% by weight), but the bigger difference is timing: propionate clears far faster, so it needs more frequent injections to hold steady levels. Neither is inherently "stronger" once you match total testosterone.

Can I switch ester without changing my dose?

Switching esters changes both the weight fraction and the schedule, so the equivalent dose and frequency shift. Treat it as a new protocol set by your prescriber rather than a one-to-one swap.

Why is propionate harder to find in the US?

Cypionate is a stocked, FDA-labelled product, whereas propionate is far less commonly marketed in the US and is often supplied through compounding pharmacies. Availability and concentration can vary, so check your specific vial label.

Do I draw more units for one ester than the other?

No — units depend only on the vial concentration and your milligram dose, not the ester name. A 50 mg dose from a 200 mg/mL vial is 25 units whether it is cypionate or propionate.

Sources

This guide is for general educational purposes only and does not constitute medical advice. Always follow your prescriber’s specific instructions and consult a qualified clinician before changing any protocol.