Tape reader and fraction rounding

Read feet, inches and a proper fraction as decimal feet, inches and metres, then round to a tape division from 1/2 to 1/64 inch.

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Result

Decimal feet: 2.291666666667 ft
Decimal inches: 27.5 in
Metres: 0.6985 m
Rounded decimal feet: 2.291666666667 ft
Rounded decimal inches: 27.5 in
Rounded feet, inches and fraction: 2 ft 3 1/2 in

Not engineering advice. Have a licensed professional check every result. Not a substitute for a licensed engineer, the manufacturer's data or the authority having jurisdiction; confirm the code edition your jurisdiction has adopted. Converts units only; this is not a code reading. Exact unit definitions with no code limit, so no trade check is pending. Terms of use and estimate disclaimer.

Working

Add the tape parts
$I = 12F + i + n/d$
12 × 2 + 3 + 1/2
= 27.5 in
Round to a tape division
$I_r = R(I d_r)/d_r$
nearest rounding of 27.5 × 16, divided by 16
= 2 ft 3 1/2 in

Working is shown in the units each formula is written in; the result figures above follow the unit switch. A numeric input is taken to 15 significant digits before it is used (1033.2293579541322 kg is used as 1033.22935795413 kg); every echo of it shows that value, and a computed figure substituted into the working is quoted to 15 significant digits as well.

Notes

Converts units only; this is not a code reading. The decimal results preserve the input measurement before rounding. Rounded results use the selected tape division.
Feet and the fraction numerator must be whole numbers. Inches can include a decimal and must be less than twelve; the proper fraction is added to those inches. Measurements are nonnegative. Nearest ties round up. Fractions are reduced and carry into the next inch or foot.

Method

Read the tape

Add twelve times the whole feet, the inches and numerator divided by denominator. Decimal outputs show the measurement before rounding. Feet and the numerator must be whole numbers; measurements are nonnegative.

Round to a tape division

Multiply total inches by the selected denominator, round that division count, then divide by the denominator. Nearest ties round up; up takes the ceiling and down takes the floor. Reduce the fraction and carry twelve inches into a foot. The default is nearest to 1/16 inch.

Limits and sources

Converts units only; this is not a code reading. No code-derived number or engineering limit is used. Not engineering advice. Have a licensed professional check every result.

Factors come from exact unit definitions. Source URLs were tried by plain GET on 2026-10-13 and returned HTTP 403, so comparison with the NIST printed rows remains unverified. The exact definitions and derivation are recorded in this tool's spec.

Formulas

Tape to decimal inches

I = 12 F + i + n/d

I = 12F + i + n/d

Round to a tape division

I_r = R(I × denominator) / denominator; nearest ties up, up = ceiling, down = floor

I_r = R(I d_r)/d_r

Basis: engineering method

Standard	Edition	Clause	What it covers
NIST SP 811, Guide for the Use of the International System of Units	n/a	Appendix B.8 and B.9	Exact unit definitions, SI prefixes and derived arithmetic. https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8 ; https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b9 . Source fetch 2026-10-13: HTTP 403; printed rows unverified.
NIST Handbook 44, unit definitions	n/a	Appendix C	International foot and inch; avoirdupois pound and ounce; US liquid gallon is 231 cubic inches. https://nvlpubs.nist.gov/nistpubs/hb/2026/NIST.HB.44-2026.pdf . Source fetch 2026-10-13: HTTP 403; printed rows unverified.

Rules are restated in our own words and computed for your inputs; no table or text from a standard is reproduced. The adopted edition varies by jurisdiction, so confirm the one your authority having jurisdiction enforces.

Inputs

Input	Unit	Range	Default
Whole feet `feet`		0 to 100000000	2
Inches `inches`		0 to 12	3
Fraction numerator `numerator`		0 to 63	1
Fraction denominator `denominator`	choice	2, 4, 8, 16, 32, 64	2
Round to nearest tape division `roundTo`	choice	2, 4, 8, 16, 32, 64	16
Rounding direction `direction`	choice	nearest, up, down	nearest

Worked examples

Each example below is a test the calculator must pass before it ships. The expected values were worked out by a separate implementation.

Example	Expected result (each in its declared unit)
Two feet, three and a half inches	decimalInches: 27.5 in, roundedMeasurement: 2 ft 3 1/2 in
An exact sixty-fourth inch	decimalInches: 0.015625 in, roundedMeasurement: 0 ft 0 1/64 in
Rounding carries into the next foot	roundedMeasurement: 1 ft 0 in, roundedInches: 12 in

For AI agents

This calculator is also the MCP tool convert_tape at https://elevatorcalc.com/api/mcp, using the same function as this page. See how to connect, the llms.txt file, or the JSON catalogue.