What Is Carbon Dating and How Does Radiocarbon Dating Work?

Carbon dating, also called radiocarbon dating, estimates the age of once-living material by measuring how much carbon-14 remains in a sample. It works because living things continually take in carbon from their environment, including a small amount of radioactive carbon-14, and that intake stops when they die. From that point, the carbon-14 decays at a known rate, so the remaining amount acts as a clock. The method is most useful for organic materials and carbonates up to roughly 50,000 years old, and modern labs typically measure the carbon-14 using accelerator mass spectrometry (AMS).

The Principle Behind Carbon Dating

Carbon-14 is created in the upper atmosphere and cycles into plants through photosynthesis and into animals through the food chain. While an organism is alive, its carbon-14 level stays roughly in balance with the atmosphere. When it dies, no new carbon-14 is added, and the existing carbon-14 begins to decay into nitrogen-14.

The decay is steady and measurable: carbon-14 has a half-life of about 5,730 years. That means after one half-life, half of the original carbon-14 remains; after two, a quarter remains, and so on. A lab measures the ratio of remaining carbon-14 to stable carbon and calculates an estimated age from that ratio.

From Measurement to Age Estimate

The calculation is not a simple raw count. Labs calibrate radiocarbon results against known reference records, such as tree rings and other independently dated materials, to convert the measured carbon-14 into a calendar-age estimate. This is why a reported radiocarbon age and a calibrated calendar age can differ.

What Samples Can Be Dated

Radiocarbon dating applies to materials that once exchanged carbon with the environment. According to the SGS Beta Carbon Dating Service, common sample categories include:

The lab notes that expert technical support helps clients analyze the most suitable samples, which matters because sample type, preservation, and contamination all affect whether a reliable date can be produced.

How AMS Dating Fits In

Accelerator mass spectrometry (AMS) is a common modern technique for measuring radiocarbon. Instead of waiting for radioactive decay events to accumulate, AMS counts carbon-14 atoms directly. This generally allows smaller samples to be dated than older decay-counting methods, and it is the approach many radiocarbon laboratories use for routine work.

SGS Beta states that it provides AMS dating results in 3–14 business days, which gives a sense of the turnaround a client can expect from a commercial lab.

Practical Age Range and Limitations

Carbon dating has boundaries worth knowing before submitting a sample:

• Upper limit: Because carbon-14 decays away, samples older than roughly 50,000 years generally retain too little for a reliable measurement.
• Contamination: Added or removed carbon from the environment can shift results, so sample selection and pretreatment matter.
• Material type: Only materials that once took in carbon can be dated this way; rocks and minerals that never incorporated carbon-14 are not suitable.
• Calibration: Raw radiocarbon measurements are converted to calendar ages using calibration curves, so the reported age depends on that step.

Planning Around Lab Schedules

If you are preparing to submit samples, it helps to check a lab's operating calendar. SGS Beta publishes a 2026 holiday and lab closure schedule, including closures around November 19, November 26–27 (Thanksgiving), and December 24, 2026 through January 1, 2027 for Christmas and New Year. Factoring these dates in can prevent unexpected delays in turnaround.

For anyone trying to understand an archaeological, geological, or forensic timeline, carbon dating remains a core tool: it turns the steady decay of carbon-14 into a measurable estimate of age for bones, teeth, shells, plants, seeds, and wood.