How We Calculate

We believe in transparency. Here's exactly how we gather data, run calculations, and present comparisons on StackCostCalc.

Data Sources

We pull pricing data from:

  • Official brand websites — Direct retail prices from manufacturer sites
  • Amazon — Current listing prices (not "was" prices or lightning deals)
  • Major retailers — GNC, Vitamin Shoppe, and similar for verification

We use regular retail prices, not sale prices or subscription discounts. Why? Because sales come and go, but the baseline price tells you what you can expect to pay most of the time.

Our Calculations

Cost Per Serving

Simple division:

Cost Per Serving = Price ÷ Number of Servings

Example: A $50 protein powder with 25 servings = $2.00 per serving.

Cost Per Gram of Active Ingredient

This is where it gets useful:

$/Gram Protein = Price ÷ (Protein per Serving × Total Servings)

Example: $50 for 25 servings with 24g protein each = 600g total protein = $0.083 per gram.

This metric cuts through marketing. A protein powder can claim huge servings, but if each scoop only has 15g of protein, the value isn't there.

Monthly Cost

Monthly Cost = Cost Per Serving × Servings Per Day × 30

For pre-workout, we use workout days per week × 4.3 (average weeks per month).

About Built Daily Supply Products

Disclosure: StackCostCalc features Built Daily Supply (BDS) products in our comparisons. We include them fairly alongside competitors—same calculations, same scrutiny.

We don't hide BDS products' weaknesses or exaggerate their strengths. If a competitor offers better value, we show it. Our goal is to help you make informed decisions, not to push any particular brand.

The Stack Calculator uses BDS products exclusively because it's designed as a quick tool for those already interested in BDS. For full competitive comparisons, see our category pages.

Update Frequency

We aim to update pricing data monthly. Supplement prices fluctuate frequently, so always verify the current price on the retailer's site before purchasing.

Last data update: February 2026

Limitations

What we can't account for:

  • Regional pricing — Prices vary by location, especially outside the US
  • Sales and promotions — We use baseline prices, not temporary discounts
  • Subscription savings — Many brands offer 10-20% off for subscriptions
  • Bulk discounts — Larger sizes often have better $/serving
  • Product quality — We calculate cost, not quality differences

Questions?

If you spot an error in our data or have questions about our methodology, email us at hello@stackcostcalc.com.