Formula
Rounded value = round(value ÷ increment) × increment for nearest rounding. Use ceiling(value ÷ increment) × increment to round up, or floor(value ÷ increment) × increment to round down.
Rounding Calculator
Round a number to decimal places or a chosen increment, with nearest, up and down modes, formula notes and a printable rounding-rule record.
Worked example
For 123.4567 rounded to the nearest 0.01, divide by 0.01 to get 12,345.67. Round that to 12,346, then multiply by 0.01. The result is 123.46. If the increment were 0.05, the nearest result would be 123.45.
Professional note
Master’s Tip: write down the rounding rule before the rounded answer. “Nearest cent”, “always round up to a pack”, and “round down to a conservative estimate” can produce different records from the same starting number.
Regional and unit assumptions
Standard or basis: transparent decimal arithmetic using user-selected increments. No tax, accounting, education, scientific-significant-figures or payroll standard is claimed.
Rule proof
Same number, different rule
Rounding is a chosen rule, not only a shorter display. The calculator divides by the selected increment, applies nearest, up or down rounding, then multiplies back so the original number and rule can be audited.
Visible checks
What the page now proves
- Original number retained
- Increment shown
- Nearest/up/down method separated
Assumptions and limitations
- Mode 0 rounds to the nearest increment; halfway cases follow JavaScript Math.round behavior, which rounds 0.5 upward toward positive infinity.
- Mode 1 always rounds upward with ceiling arithmetic; mode 2 always rounds downward with floor arithmetic.
- The increment must be positive. Common increments are 1, 0.1, 0.01 and 0.05.
- The displayed decimal places control formatting only; the rounding increment controls the arithmetic.
- Financial, tax, scientific, school and payroll records may require official rounding rules that differ from this general calculator.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
Rounded value = round(value ÷ increment) × increment for nearest rounding. Use ceiling(value ÷ increment) × increment to round up, or floor(value ÷ increment) × increment to round down.
Standard or basis
Standard or basis: transparent decimal arithmetic using user-selected increments. No tax, accounting, education, scientific-significant-figures or payroll standard is claimed.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
Master’s Tip: write down the rounding rule before the rounded answer. “Nearest cent”, “always round up to a pack”, and “round down to a conservative estimate” can produce different records from the same starting number.
Related calculators
Questions
How do I round to two decimal places?
Use an increment of 0.01 and choose nearest mode. The calculator divides by 0.01, rounds to a whole step, and multiplies back.
How do I round to the nearest whole number?
Set the increment to 1. A value of 123.4567 rounds to 123 in nearest mode and 124 in upward mode.
What is the difference between rounding up and rounding down?
Rounding up uses ceiling arithmetic and moves to the next step at or above the number. Rounding down uses floor arithmetic and moves to the step at or below the number.
Can I round to the nearest 0.05?
Yes. Enter 0.05 as the increment. This is useful for five-cent cash rounding, workshop tolerances and quote notes where the chosen rule is appropriate.
Is this the same as significant figures?
No. This page rounds to decimal places or fixed increments. Significant-figure rounding uses a different rule based on meaningful digits.
Calculation note
Rounding is a practical compromise between exact arithmetic and usable records. It appears in money, measurement, classroom work, timesheets and engineering notes, but the correct rule depends on context.
Rounding is a rule, not just a shorter number
A rounded number is easier to read, but it is also less detailed than the original measurement or calculation. That is why the calculator keeps the original value, increment and mode visible in the printable report.
Fixed increments are common in real records
Many everyday records round to a fixed step: cents use 0.01, whole units use 1, cash rounding may use 0.05, and some time records use 5, 6, 10 or 15-minute increments. The arithmetic is simple only after the increment is chosen.
Official rules can override generic arithmetic
Tax invoices, lab results, school grading, payroll systems and regulated measurements may specify a particular rounding convention. This page gives the transparent arithmetic check, not a substitute for the governing rule.
Sources and further readingNIST: Guide for the Use of the International System of UnitsMDN Web Docs: Math.round()