Calculator Methodology | PeptiCompute

Units and assumptions

One milligram (mg) is 1,000 micrograms (mcg). Liquid volume is expressed in milliliters (mL). U-100 is treated as 100 scale units per mL; one scale unit therefore represents 0.01 mL. These volume markings are not a universal measure of mass or biological activity.

The calculation assumes a uniform solution and uses the final volume you enter. It does not model displacement, material loss, purity, stability, solubility or equipment precision.

The complete formula set

Mass normalization: mcg = mg × 1,000; mg = mcg ÷ 1,000
Concentration: mcg/mL = vial mass in mcg ÷ final volume in mL
Concentration in mg/mL: mg/mL = mcg/mL ÷ 1,000
Target volume: mL = target mass in mcg ÷ concentration in mcg/mL
U-100 equivalent: Scale units = volume in mL × 100
Amount per scale unit: mcg per U-100 unit = concentration in mcg/mL ÷ 100
Theoretical portions: Portions = vial mass in mcg ÷ target mass in mcg
Reverse calculation: mL = U-100 units ÷ 100; mcg = mL × concentration in mcg/mL

Arithmetic example — not a recommendation

For 5 mg in 2 mL, normalized mass is 5,000 mcg and concentration is 2,500 mcg/mL (2.5 mg/mL). A user-entered 250 mcg target corresponds to 0.1 mL, 10 U-100 units and 20 theoretical portions. Each unit corresponds to 25 mcg. Reversing the marking of 10 returns 0.1 mL and 250 mcg (0.25 mg).

Parsing and technical bounds

Use a dot for decimals; decimal scientific notation is accepted. Empty text, nonfinite numbers, comma-separated values, negative masses, unsupported units and ambiguous shared parameters are rejected. Both mass inputs must be at least 10⁻⁹ mcg and less than 10⁹ mcg. Volume must be at least 10⁻⁹ mL and less than 10⁶ mL. Reverse markings may be zero and must be less than 10⁶ units.

These broad software limits prevent underflow, overflow and interface abuse. They are not clinical limits or a statement that an amount is appropriate. A result may exceed the illustrated scale range or entered vial amount; any such mismatch is identified without changing the arithmetic.

Rounding and precision

Calculations use JavaScript floating-point numbers without intermediate rounding. Concentration and ratios display up to four decimal places, volumes up to six, scale units up to two, and masses up to three. Smaller nonzero values and very large outputs use scientific notation. Approximation symbols in Formula Inspector reflect display rounding, not a different formula.

Input uncertainty and significant figures are not measured by this software. Results may have more displayed digits than the precision of the source measurements. No display value certifies that a physical marking is measurable.

Independent checks

Reference cases include 5 mg / 2 mL / 250 mcg; 10 mg / 2 mL / 0.5 mg; and 2 mg / 1 mL / 100 mcg. The tests also check that volume × concentration reproduces target mass, portions × target mass reproduces vial mass, and forward/reverse calculations agree within an explicit floating-point tolerance.

Provenance

Calculation engine: Deterministic arithmetic that runs in your browser.
Milestone: MVP — one engine shared by all six calculators.
Verification: Independently regression-tested against fixed reference cases and cross-checked between all six calculators.
Last verified: September 2026

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