p21 calculator

5 mg in 2 mL = 2.5 mg/mL; 10 units on a U-100 syringe holds 0.25 mg.

Sizes on sale: 5mg. Choose a vial, the water and the amount per draw; prices are the lowest current US offers.

search a compound or a supplier’s vial

amount in the vial

bacteriostatic water added

amount per draw

syringe · picked to fit the draw

price, vial size and certificate correction

vial price (optional)

USD

Lowest current US offer for this size.

vial holds (optional)

Most 2–15 mg vials hold 3 mL.

measured content on the COA

From the lot certificate; it replaces the label amount.

or HPLC purity

Certificates on file for this compound:

American Peptides 5mg · lot P21-5-0318 · 2026-06-17 · Bioviridian Inc.: 5.25 mg measured, 99.8% purityCOA

2.5 mg/mL

10 units holds 0.25 mg

concentration: 2.5 mg/mL
per unit: 25 mcg per unit
full draws per vial: —
cost per draw: —

the working

5 mg ÷ 2 mL = 2.5 mg/mL

If this is a prescription, the dose and volume on your pharmacy label take priority. Ask your pharmacist about any mismatch.

cheapest way to buy it

vendor	size	price	$/mg	checked	calculate with this vial, or view it
American PeptidesCOA 5.25 mg	5mg	$120.00	$24.00	2026-11-06	view, P21 5mg at American Peptides, opens in a new tab

In-stock US offers checked in the last 7 days, before shipping. The featured partner is a paid placement and is labelled; order here is by price per mg.

updated Nov 4, 2026 · exact arithmetic, checked against 21 worked cases · prices from offers checked in the last 7 days

animal studies only

P21 dosing evidence

No human studies; P021 has been studied only in mouse and rat models. PeptideTech does not list unsourced doses.

P21 5mg in 2 mL

amount to syringe units

P21 5 mg in 2 mL: amount to syringe units
amount	mL	U-100 units	U-40 units
100 mcg	0.04	4	1.6
250 mcg	0.1	10	4
500 mcg	0.2	20	8
1 mg	0.4	40	16
2 mg	0.8	80	32
2.5 mg	1	100	40
5 mg	2	200	80

One unit on a U-100 syringe is 0.01 mL; on a U-40 it is 0.025 mL.

every P21 vial size on sale

reconstitution chart

Concentration and amount per 10 units for P21 vial sizes and water volumes
vial	1 mL water	2 mL water	3 mL water	5 mL water
5 mg	5 mg/mL 10 units = 0.5 mg	2.5 mg/mL 10 units = 0.25 mg	1.667 mg/mL 10 units = 0.167 mg	1 mg/mL 10 units = 0.1 mg

10 units on a U-100 syringe is 0.1 mL. Every cell is exact arithmetic: amount ÷ water.

what the numbers mean · where they come from

terms and sources

Label amount or measured amount. The calculator starts from the amount printed on the vial. A lot certificate’s measured content (net peptide content, in mg) can replace it for the vial that was tested. HPLC purity is a share of peak area, not a mass, so a purity-only correction is shown as an estimate. See HPLC, certificate of analysis and how to read a peptide COA.
Concentration. Amount in the vial ÷ water added. Terms: reconstitution, bacteriostatic water, lyophilized.
Syringe units. A volume: 0.01 mL per unit on a U-100 syringe, 0.025 mL on U-40. Units say nothing about the compound until the concentration is known.
Cost per draw. Vial price × amount per draw ÷ vial amount, from the price per mg of a current offer. Offers come from the P21 price comparison; certificates from the COA library.

Arithmetic only, on the numbers entered. Amounts from labels or trials are cited references, not recommendations; PeptideTech does not give personal use instructions and does not test products.

short answers

P21 calculator questions

How much bacteriostatic water do I add to P21 5mg?

Any volume the vial holds; 2 mL gives 2.5 mg/mL, so 10 units on a U-100 syringe holds 250 mcg. More water makes each draw read more units. The table below shows 1–5 mL for every P21 vial size on sale.

What changes the calculated concentration?

Only two inputs: the amount of P21 in the vial and the water added. 5mg in 2 mL is 2.5 mg/mL; twice the water halves it, and the amount per draw then reads twice the units. A lot certificate's measured content replaces the label: American Peptides's 5mg lot P21-5-0318 measured 5.25 mg, which in 2 mL is 2.625 mg/mL. HPLC purity is a share of peak area, not a measured mass, so it is shown only as an estimate.

What doses of P21 were used in research?

No human studies; P021 has been studied only in mouse and rat models. PeptideTech does not list unsourced doses.

What does P21 cost per mg?

The lowest current US price is $120.00 for 5mg at American Peptides (about $24.00 per mg, checked 2026-11-06). The calculator turns any vial price into cost per draw.

How much P21 is really in the vial?

Lot certificates on file report measured content: for example American Peptides's 5mg lot P21-5-0318 measured 5.25 mg at 99.8% purity. Use the certificate correction to calculate from the measured amount.

more calculators

Volume and concentration arithmetic for laboratory reconstitution; not medical advice. API: /api/calc. Syringe scales: 0.3 mL U-100, 0.5 mL U-100, 1 mL U-100, 0.5 mL U-40, 1 mL U-40, 1 mL syringe, 3 mL syringe.