How much NAD+ do you have left?
The NAD+ Clock — an estimate of how the “cellular battery” changes with age, based on published research.
Data verified September 4, 2026.
Estimate from one published skin study, not a measurement of your NAD+ level. Blood studies found little or no decline. How we calculated this →
What is NAD+?
NAD+ is a molecule every cell uses to turn food into energy and to repair DNA. Think of it as the charge in a battery: your cells spend it constantly and make more to replace it. Some studies suggest that with age, cells make a little less and use up more, so the battery may slowly drain — though not all research agrees, and blood levels may not reflect what happens inside tissue.
Why get NAD+ from a clinician?
NAD+ is sold in a lot of places, from IV lounges to unregulated online sellers. At Measured, a licensed provider reviews your health history and screens for the conditions where NAD+ is not appropriate, including pregnancy, breastfeeding, a history of cancer, and kidney disease. Prescriptions are filled by independent, state-licensed pharmacies, and a registered dietitian is part of your plan. Before you start, we tell you what the evidence shows and what it does not: NAD+ injections are compounded and not FDA-approved, and no clinical trial has yet tested them for energy, focus, or aging. If you decide to proceed, you do it with accurate information and a clinician who is accountable for your care.
Estimated NAD+ by age
The same estimates the tool uses, from one published skin-tissue study. Not a measurement of any individual.
| Age | Estimated NAD+ vs. age 20 |
|---|---|
| 20 | 100% |
| 30 | 76% |
| 40 | 57% |
| 50 | 44% |
| 60 | 33% |
| 65+ | 29% |
Source: curve fitted by Measured to Massudi et al., PLOS ONE 2012. Methodology below.
How we calculated this
- One skin-tissue study.Human skin samples from 49 people aged 0–77 showed NAD+ falling with age. We fitted one curve to that study’s group averages: it halves roughly every 25 years from age 20 and levels off after about 65 (Massudi et al., PLOS ONE, 2012; curve fit by Measured). The study reports correlations and group averages, not a rate — the half-life is our arithmetic — and its finding has not been replicated.
- The largest blood studies disagree. Whole blood from 1,518 adults showed no overall change with age; only men over 60 were modestly lower, and women showed no trend (Yang et al., Frontiers in Endocrinology, 2022). A 2026 study across seven cohorts found whole-blood NAD+ essentially stable with age (Trętowicz et al., Nature Metabolism, 2026). The tool shows the sex finding in its message line; the estimate itself uses one curve for everyone.
- Tissue and blood may tell different stories. A small 2015 brain-imaging study reported a decline, but a 2020 replication in 50 people found only a small, non-significant change. Reviews conclude the evidence for an overall decline is limited and often restricted to a single tissue. Whether tissue and blood differ is unresolved.
- What the tool does not tell you. It does not measure your NAD+ level, and it does not say whether raising NAD+ changes health or aging — no human outcome trial has shown that. Read what the evidence says about NAD+ injections.
Learn more
Frequently asked questions
Is this my real NAD+ level?+−
No. It is a population-level estimate derived from a published study. Your actual level can only be determined by laboratory testing, and individual levels vary widely.
Where do these numbers come from?+−
From a curve Measured fitted to the group averages in a published study of human skin tissue (Massudi et al., 2012). Other studies, especially blood studies, show smaller or no change with age. The “How we calculated this” section on this page explains the methodology and the disagreement.
Why does the tool ask my sex?+−
The largest blood study of NAD+ and age (1,518 adults) found a modest decline in men over 60 and little change in women. The tool shows that finding in its message; the estimate itself uses one curve for everyone.
Can NAD+ levels be raised?+−
Blood NAD+ can be raised with precursors such as nicotinamide riboside or NMN, and with NAD+ infusions or injections. Whether raising it improves health or slows aging has not been established in humans.
Is NAD+ therapy FDA-approved?+−
No. NAD+ injections are compounded drugs, which are not FDA-approved: FDA has not evaluated their safety or effectiveness, and it has documented contaminated compounded NAD+ that sent patients to the emergency room. That is the strongest reason to get it through a licensed clinician rather than an IV lounge or an online seller. At Measured, a provider reviews your health history and screens for the conditions where NAD+ is not appropriate, prescriptions are filled by state-licensed pharmacies, and you are told what the evidence shows before you start.
For educational purposes only. This tool is not medical advice and does not diagnose, treat, cure, or prevent any disease or condition. It shows a population-level estimate derived from a single published tissue study and a curve fitted by Measured; it does not measure your NAD+ level, and individual levels vary widely. Research on whether NAD+ declines with age is mixed, and the health effects of raising NAD+ have not been established in humans. NAD+ injections are compounded drugs that are not FDA-approved; FDA has not evaluated their safety or effectiveness. Measured offers NAD+ therapy. Talk to a licensed healthcare provider before starting, stopping, or changing any treatment.