Spray Mix Calculators Re-Entry Interval Calculator
Pesticide Re-Entry Interval (REI) Calculator
Calculate safe re-entry time after any pesticide application. Includes a product REI lookup for 30+ common products, tank mix checker, PHI harvest planner, and a printable WPS field posting notice.
⚠️ The label REI is a legal requirement.
This calculator is a planning aid only. Always verify the REI on your specific product label. Product lookup values are typical references — formulations vary.
On this page: Calculator · REI vs PHI · Common REI chart · How WPS works · Related tools · FAQ
Just mixed a batch? Sprayer Calibration Calculator · Need mix amounts? Spray Mix Calculator.
REI Timer, Tank Mix & PHI Planner
Choose a mode: REI Timer for a single product · Tank Mix to find the governing REI across two products · PHI Planner for safe harvest date.
Not sure of your REI? Check the "Agricultural Use Requirements" box on your product label, or look it up on the CDMS Label Database or Greenbook.
When tank mixing, the longest REI of all products governs safe re-entry. Enter both products — the calculator automatically applies the higher REI.
Product A
Product B
Application Time
⚠️ Always check each product label individually — some labels specify additional restrictions for specific tank mixes. This calculator only compares REIs, not tank mix compatibility.
The Pre-Harvest Interval (PHI) is the minimum number of days between the last application and harvest. Enter your spray date and PHI days to calculate the earliest safe harvest date.
Note: PHI is separate from REI — you must comply with both. If you applied multiple products, use the longest PHI of all products. PHI only applies to food crops; for non-crop uses, only REI applies.
🦺 Spraying around workers or family?
Always use proper PPE:
chemical-resistant gloves and
a full
spraying PPE kit.
See all recommended spray equipment.
Common pesticide REI reference chart
Typical REI values for common pesticide types. Always confirm against your specific product label — the label REI is the legal standard.
| Pesticide Type / Active Ingredient | Typical REI | Notes |
|---|---|---|
| Glyphosate (Roundup, etc.) | 4 hours | Most formulations; verify label |
| 2,4-D amine | 12 hours | Varies by formulation |
| Dicamba (Banvel, Clarity) | 24 hours | Some formulations 48 hours |
| Dicamba (XtendiMax, Engenia) | 48 hours | Always verify — drift-sensitive product |
| Paraquat (Gramoxone) | 24 hours | Restricted-use pesticide |
| Organophosphate insecticides | 24–48 hours | High-hazard — always check label |
| Pyrethroid insecticides | 12 hours | Bifenthrin, permethrin, lambda-cyhalothrin |
| Neonicotinoids (foliar) | 12 hours | Imidacloprid, thiamethoxam |
| Spinosad | 4 hours | OMRI-listed; low REI |
| Strobilurin fungicides | 12 hours | Azoxystrobin, trifloxystrobin |
| Triazole fungicides | 12 hours | Propiconazole, tebuconazole |
| Copper-based fungicides | 24 hours | Copper hydroxide, copper sulfate |
| Biological / OMRI | 4 hours | Many have 0–4 hr REI; always check |
⚠️ Reference only. The product label is the legal document.
Frequently asked questions
What is a pesticide re-entry interval (REI)?
A Restricted-Entry Interval (REI) is the minimum time that must pass after a pesticide application before workers can enter the treated area without full PPE. REIs are legally required under the EPA Worker Protection Standard (WPS).
How long after spraying is it safe to re-enter?
It depends entirely on the product. Common REIs range from 4 hours (glyphosate, spinosad) to 12, 24, or 48 hours for more hazardous products. Always follow your specific product label — it is a legal requirement.
When tank mixing two pesticides, which REI applies?
The longest REI of all products in the tank mix governs safe re-entry. Mixing glyphosate (4-hr REI) with 2,4-D amine (12-hr REI) means you must wait 12 hours. Use the Tank Mix tab to determine this automatically.
What is the difference between REI and PHI?
REI is a worker safety interval in hours. PHI is a food safety interval in days between the last application and harvest. Both are separate legal requirements — use the PHI Planner tab to calculate your harvest-safe date.
What is a typical REI for glyphosate (Roundup)?
Most glyphosate-based products carry a 4-hour REI. Always check your specific product label as formulations vary.
What must be posted at a treated area under WPS rules?
Warning signs must be posted at all entry points, or workers must be verbally informed before entry. The posting must include the product name, REI, and the date/time re-entry is permitted. Use the Copy Field Notice button in the REI Timer tab to generate a compliant notice instantly.
Does rain or wind affect the REI?
No — the REI runs for the full stated hours from when spraying ends, regardless of weather conditions after application.
Can I enter during the REI with proper PPE?
In some cases yes — the label specifies whether early entry is permitted and what PPE is required. If the label does not list early entry provisions, you must wait the full REI.