Pre Harvest Interval Calculator

Work out pre harvest interval instantly with clear inputs, formula shown and shareable results.

About Pre Harvest Interval Calculator

The pre-harvest interval is the minimum number of days that must pass between the last pesticide application and harvest so residues fall below the maximum residue limit. Adding a few days of buffer absorbs slow degradation in cool or cloudy weather and gives margin against a residue test failure.

Formula

Pre-harvest interval

Earliest legal harvest = last application date + PHI days; recommended = + safety buffer

Worked example

With the default values below, Pre Harvest Interval Calculator returns Recommended Harvest Date of April 25, 2026. Change any input above and every figure here is recalculated in your browser.

Inputs used

Date Of Last Application: 2026-04-01
Pre-Harvest Interval On Labelminimum 0 days: 21 days
Safety Bufferminimum 0 days: 3 days
Planned Harvest Date: 2026-04-20

Results

Recommended Harvest Date: April 25, 2026
Earliest Legal Harvest Date: April 22, 2026
Planned Date Status: Too early - do not harvest
Extra Days To Wait: 5

Step by step

1Values used
2Pre-harvest interval
3Recommended Harvest Date= 2026-04-25
4Earliest Legal Harvest Date= 2026-04-22
5Planned Date Status= Too early - do not harvest
6Extra Days To Wait= 5

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
The pre-harvest interval is a legal requirement, not a guideline. Always use the interval printed on the label for your crop and jurisdiction, and keep records of every application date.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

The pre-harvest interval is a legal requirement, not a guideline. Always use the interval printed on the label for your crop and jurisdiction, and keep records of every application date.

Frequently Asked Questions

What happens if I harvest before the PHI?

Residues are likely to exceed the MRL. The consignment can be rejected, recalled or destroyed, and repeated failures can cost market access for a whole region.

Does the PHI depend on the crop as well as the product?

Yes. The same active ingredient can carry very different intervals on grapes, tomatoes and cereals because residue decline and MRLs differ. Always read the crop-specific line on the label.