SeqBench

Human (H. sapiens) Codon Usage

For every amino acid with more than one synonymous codon, Human (H. sapiens)uses some codons far more often than others. The table below shows each codon's usage fraction — the share of that amino acid's codons it accounts for — with the preferred (most-used) codon highlighted.

Amino acid1-letter3-letterCodonFraction
AlanineAAlaGCT27%
AlanineAAlaGCC40%preferred
AlanineAAlaGCA23%
AlanineAAlaGCG11%
ArginineRArgCGT8%
ArginineRArgCGC18%
ArginineRArgCGA11%
ArginineRArgCGG20%
ArginineRArgAGA21%preferred
ArginineRArgAGG21%
AsparagineNAsnAAT47%
AsparagineNAsnAAC53%preferred
Aspartic acidDAspGAT46%
Aspartic acidDAspGAC54%preferred
CysteineCCysTGT46%
CysteineCCysTGC54%preferred
Glutamic acidEGluGAA42%
Glutamic acidEGluGAG58%preferred
GlutamineQGlnCAA27%
GlutamineQGlnCAG74%preferred
GlycineGGlyGGT16%
GlycineGGlyGGC34%preferred
GlycineGGlyGGA25%
GlycineGGlyGGG25%
HistidineHHisCAT42%
HistidineHHisCAC58%preferred
IsoleucineIIleATT36%
IsoleucineIIleATC47%preferred
IsoleucineIIleATA17%
LeucineLLeuTTA8%
LeucineLLeuTTG13%
LeucineLLeuCTT13%
LeucineLLeuCTC20%
LeucineLLeuCTA7%
LeucineLLeuCTG40%preferred
LysineKLysAAA43%
LysineKLysAAG57%preferred
MethionineMMetATG100%preferred
PhenylalanineFPheTTT46%
PhenylalanineFPheTTC54%preferred
ProlinePProCCT29%
ProlinePProCCC32%preferred
ProlinePProCCA28%
ProlinePProCCG11%
SerineSSerTCT19%
SerineSSerTCC22%
SerineSSerTCA15%
SerineSSerTCG5%
SerineSSerAGT15%
SerineSSerAGC24%preferred
ThreonineTThrACT25%
ThreonineTThrACC36%preferred
ThreonineTThrACA28%
ThreonineTThrACG11%
TryptophanWTrpTGG100%preferred
TyrosineYTyrTAT44%
TyrosineYTyrTAC56%preferred
ValineVValGTT18%
ValineVValGTC24%
ValineVValGTA12%
ValineVValGTG46%preferred
Stop*StopTAA30%
Stop*StopTAG24%
Stop*StopTGA47%

Optimize a protein for Human

Paste a protein sequence and every residue is rewritten with its preferred Human codon — the same engine behind the full Codon Optimizer tool, scoped to this one organism.

Frequently asked questions

What is the preferred codon for each amino acid in Human?

The codon with the highest usage fraction for that amino acid in Human (H. sapiens) — highlighted in green in the table below. It's the codon a codon optimizer picks when rewriting a gene for this host.

What's a rare codon to avoid in Human?

TCG (Serine) is used only 5% of the time among its synonymous codons in Human (H. sapiens) — a run of codons like this can slow translation if the matching tRNA is scarce.

How do I codon-optimize a gene for Human?

Paste the protein sequence into the tool below (or the full Codon Optimizer), and every residue is rewritten with its most-used codon in Human (H. sapiens) — the encoded protein is unchanged, only the DNA sequence changes.

Are these values exact?

These fractions are reference approximations derived from the Kazusa Codon Usage Database for Human (H. sapiens). For critical work, verify against your specific expression system rather than treating any single table as definitive.