Stable Isotope Calculator

Convert and interpret stable isotope delta values. Analyze carbon-13 and nitrogen-15 ratios for dietary reconstruction, trophic level estimation, and C3/C4 plant consumption patterns.

Dietary Interpretation
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C3 vs C4 Signal
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Trophic Level (est.)
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Marine % (est.)
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Quality Check
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13C/12C Ratio (x10^-3)
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15N/14N Ratio (x10^-3)
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Stable Isotope Formulas

delta = ((R_sample / R_standard) - 1) * 1000

R_sample = R_standard * (1 + delta/1000)

R_VPDB (13C/12C) = 0.011237

R_AIR (15N/14N) = 0.003676

Trophic Level ~ (d15N - baseline) / 3.4 + 1

Stable isotopes of carbon distinguish C3 plants (d13C ~ -26 per mil) from C4 plants like maize (d13C ~ -12 per mil). Nitrogen-15 increases ~3.4 per mil per trophic level. Marine protein consumers show enriched d13C and d15N values compared to terrestrial diets. Acceptable C:N ratios for collagen are 2.9-3.6.

Related Calculators

Radiocarbon Dating

C-14 dating.

Bone Measurement

Skeletal measurements.

Burial Analysis

Burial demographics.

Pollen Analysis

Palynology.

Faunal Dating

Faunal assemblages.

Carrying Capacity

Land capacity.