UTF-8 Storage Scenario Planner
Estimate byte length from counts of one-, two-, three- and four-byte code points.
Your inputs
Calculation results
Formula & assumptions
Bytes = n₁+2n₂+3n₃+4n₄; excludes BOM and does not count visible graphemes.
Values use the specified units. Calculations use floating-point arithmetic. Check input measurements and formula assumptions before applying the result.
Compare your scenarios
Save up to five results to compare changes side by side. Scenarios stay in this tab until you clear or reload it.
Using UTF-8 Storage Scenario Planner
Estimate byte length from counts of one-, two-, three- and four-byte code points.
- Enter one-byte characters, two-byte characters, three-byte characters, four-byte characters using the units printed under each field.
- Choose Calculate, or enable live updates. Review the result labels and formula assumptions.
- Save scenarios to compare up to five variations, then copy the report or download JSON or CSV.
Example
One-byte characters: 1000 code points Two-byte characters: 100 code points Three-byte characters: 50 code points Four-byte characters: 20 code points Code points: 1170 UTF-8 bytes: 1430 UTF-16 code units: 1190
Questions & answers
What does UTF-8 Storage Scenario Planner calculate?
Estimate byte length from counts of one-, two-, three- and four-byte code points.
Which units should I enter?
One-byte characters uses code points. Two-byte characters uses code points. Three-byte characters uses code points. Four-byte characters uses code points. Convert values to these units before calculating.
Which formula does it use?
Bytes = n₁+2n₂+3n₃+4n₄; excludes BOM and does not count visible graphemes.
What does the included example show?
One-byte characters: 1000 code points; Two-byte characters: 100 code points; Three-byte characters: 50 code points; Four-byte characters: 20 code points. Result: Code points = 1170; UTF-8 bytes = 1430; UTF-16 code units = 1190.
Can I compare different settings?
Yes. Save a scenario, change the inputs and save another result. Up to five scenarios are compared in this tab; they disappear when you reload or leave.
Can I export the calculation?
Copy the JSON report or download JSON and CSV with inputs, result labels and numeric values. Processing uses local JavaScript; no calculation request is sent to our server. Displayed values use up to 10 significant digits; exports retain JavaScript numeric precision.
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