Learning · official-source review · reviewed 2026-10-09
Rounding errors survive peer review when the digit count was chosen by habit instead of the standard.
Round a measured value to the digits your uncertainty supports, following the NIST SI guide conventions.
Students and technicians reporting measurements with uncertainty.
Use the source document or official route that applies to your situation. This guide does not contact another person or verify external information.
Write the uncertainty to one or two significant figures.
Round the value to the same decimal place as the uncertainty.
Apply the rounding rule your standard names, consistently.
Report the value and the uncertainty as one pair, every time.
A value of 9.8462 with uncertainty 0.05 rounds to 9.85, matching the uncertainty's hundredths place.
Use your own source and details. The example is not a record about a real person or organization.
National Institute of Standards and Technology · reviewed 2026-10-09
What this source supports: NIST SP 811 documents rounding and significant-figure conventions for reported measurements.
Source limit: Individual journals and courses may specify their own reporting conventions. Follow the rule your work requires.
These sources support the statements above. They do not show that every person needs this guide. They do not show a specific result.
This guide rounds numbers you enter. It does not compute uncertainty, validate instruments, or replace your lab's SOP.
Individual journals and courses may specify their own reporting conventions. Follow the rule your work requires.
Use current instructions from the responsible organization. This guide is a planning aid, not an official decision or a substitute for qualified advice.
Round a measured value to the decimal place supported by its uncertainty and show the reported pair.
This App rounds numbers you enter. It does not estimate uncertainty, check instruments, or apply journal-specific rules.
You enter every number yourself. The sources support the method and the limits. They do not produce a result for your specific case. Keep the original documents next to the sheet you build.
The App computes the worked example with your own numbers, in your browser.
APP 1
Round a measured value to the decimal place supported by its uncertainty and show the reported pair.
Free · no account · no upload
Open NIST-Style Rounding HelperThe App runs in this browser. It does not send or save entries. Copy, download, or print only when you choose.
This guide uses short, direct instructions as an ASD-STE100-style writing target. It is not a formal certification.
Companion App: NIST-Style Rounding Helper. It runs in this browser and does not upload your entries.
This guide is edited for clarity and checked against the sources it links. It is not a substitute for official instructions or qualified advice. A linked source does not show that every person needs this guide.