Swanson Sleep Essentials
vs
21st Century Magnesium
Supplement Comparison

  • Magnesium: 21st Century Magnesium has 8.3× more
  • Calcium: 21st Century Magnesium has 63% more
  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 10 nutrients compared
Bar chart: per-serving label amounts and listed forms for Swanson Sleep Essentials vs 21st Century Magnesium.

Try the VIOscan dashboard demo for free

Build comparison charts in seconds – no signup or card needed

This is a free preview of the $9.99/month premium dashboard

Use the interactive demo with multivitamins samples

Try Free Demo

Frequently asked questions

Which active ingredients does Swanson Sleep Essentials have?

  • Calcium appears as Calcium Carbonate
  • Magnesium appears as Magnesium Oxide
  • Melatonin
  • GABA
  • Taurine
  • Valerian Root (Valeriana officinalis)
  • Chamomile (Matricaria recutita) Flower
  • Hops (Humulus lupulus)
  • Skullcap (Scutellaria lateriflora) Extract
  • Passionflower (Passiflora incarnata)

Which active ingredients does 21st Century Magnesium have?

  • Calcium appears as Calcium Carbonate
  • Magnesium appears as Magnesium Oxide

Which categories do Swanson Sleep Essentials and 21st Century Magnesium belong to?

  • Sleep Formula
  • Mineral Complex

What health concerns do Swanson Sleep Essentials and 21st Century Magnesium address?

  • Sleep Quality
  • Muscle Support
  • General Health
  • Joint & Bone Health
  • Stress Management

Which product has a higher amount of Magnesium per serving?

  • 21st Century Magnesium has the highest total amount of Magnesium: 250 mg per serving

Which product has a higher amount of Calcium per serving?

  • 21st Century Magnesium has the highest total amount of Calcium: 65 mg per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • Swanson Sleep Essentials: 1 capsule
    • 21st Century Magnesium: 1 tablet
  • Calcium
    • This supplement has 40 mg
    • Recommended Dietary Allowance in men: 1000 mg
    • Recommended Dietary Allowance in women: 1000 mg
    • Tolerable Upper Intake Level: 2500 mg
  • Calcium
    • This supplement has 65 mg
    • Recommended Dietary Allowance in men: 1000 mg
    • Recommended Dietary Allowance in women: 1000 mg
    • Tolerable Upper Intake Level: 2500 mg

Last updated: February 19, 2026

  • Sources & Methodology: Nutrient data and forms are taken directly from Supplement Facts labels. Reviewed and standardized by the VIOscan Research Team. Learn more on the Methodology page.
  • We show the Recommended Dietary Allowance (RDA) when available. If no RDA exists, we show the Adequate Intake (AI). Tolerable Upper Intake Levels (UL) are used for upper limits. Unless otherwise noted, RDAs shown correspond to healthy adults aged 19–50 years and are sex-specific. Separate values exist for 51–70 years and >70 years, and pregnancy and lactation are excluded. All values come from the Dietary Reference Intakes (DRIs) published by the National Academies of Sciences, Engineering, and Medicine (NASEM), Food and Nutrition Board (FNB).
  • Transparency: We’re funded by our users. We don’t have sponsors or affiliate links, and we don’t sell supplements.
  • Editorial standards: we provide independent, impartial and objective data analysis.
  • This analysis is for educational purposes only. It is not a substitute for medical advice.
  • Questions? Read our Frequently Asked Questions or contact us, we’re here to help.
  • See an error? Report it through our Contact page.
  • Author: VIOscan Research Team