Glyphosate Concentrate Strengths and Mixing Rates
Every glyphosate bottle on a shelf is the same active ingredient at a different concentration, and that concentration is the whole reason mixing rates vary so much between products. Here's what the real strengths are, named product by named product, and the actual arithmetic for scaling a label rate to a 5 or 15 litre knapsack.
The short version
Consumer concentrates like Roundup Optima+ run around 170 g/L glyphosate, mixed at roughly 20 ml per litre of water. Professional concentrates run 360 g/L (Rosate 360 TF) to 490 g/L (Gallup Hi-Aktiv), the latter’s own label giving 12 ml per litre for general use. Higher concentration means less product per litre, not a stronger kill, and every professional-use product legally needs the operator to hold a Certificate of Competence. Always mix to your own bottle’s label rate, these figures are worked examples, not a substitute for it.
Real products, real concentrations, real mixing rates
Named products at their published strength, not a generic 'weak vs strong' guess.
| Product | Glyphosate | Typical mixing rate | Coverage | Who can use it |
|---|---|---|---|---|
| Ready-to-use (RTU) spray | ~7-9 g/L | Pre-diluted, no mixing | n/a, comes pre-mixed | Anyone, no certificate |
| Roundup Optima+ (consumer concentrate) | 170 g/L | ~20 ml per litre of water* | 1 litre makes up to 50 litres of spray, treating up to 1,500 sq m | Anyone, no certificate |
| Rosate 360 TF (professional) | 360 g/L | Commonly quoted at 20-25 ml per litre for knapsack use* | Check the specific pack label for the exact rate | Operator needs a Certificate of Competence, or supervision by a holder |
| Gallup Hi-Aktiv 490 (professional) | 490 g/L | 12 ml per litre of water (general use); 18 ml per litre where perennial broad-leaved weeds are present | 1 litre of made-up spray treats roughly 40 sq m | Operator needs a Certificate of Competence, or supervision by a holder |
*Rosate 360 TF’s rate is the figure commonly published across professional/amenity suppliers; check your specific pack for the exact label rate before mixing. RTU, Rosate and Gallup figures are consistent with the 7-9 g/L and 360-490 g/L range already cited on the best weed killer UK resource.
Doing the maths for your tank size
A label rate is always given per litre of water (or per hectare in a stated water volume), so scaling it up to your actual tank is simple multiplication once you have the base rate. Gallup Hi-Aktiv 490’s own label states 12 ml of product per litre of water for general hard-surface use. Scaled up: a 5 litre pressure sprayer takes 60 ml, a 15 litre knapsack takes 180 ml, a 16 litre knapsack takes 192 ml. Where perennial broad-leaved weeds are present and the label calls for the stronger 18 ml/litre rate, those same tanks take 90 ml, 270 ml and 288 ml.
Roundup Optima+ works out roughly the same way from its own label figures: a 1 litre bottle makes up to 50 litres of made-up spray, which is about 20 ml of concentrate per litre of water, so a 5 litre pressure sprayer takes around 100 ml and a 15 litre knapsack around 300 ml. Any product’s label rate scales the same way, work out the millilitres per litre first, then multiply by however many litres your tank actually holds.
One caution worth repeating: these are worked examples from published label figures for the named products above, not a substitute for reading your own bottle. Formulations change, and a label rate can vary by target weed or surface, so the number on your actual product always wins over a figure quoted here or anywhere else.
What I'd actually buy
Consumer concentrate, 170 g/L glyphosate
Roundup Optima+ Concentrate
The glyphosate concentrate line sold in garden centres and DIY stores, no certificate needed to buy or use.
1 litre makes up to 50 litres of spray solution and treats up to 1,500 sq m, around 20 ml of concentrate per litre. The straightforward starting point for a drive or path with no paperwork involved.
Professional concentrate, 360 g/L glyphosate
Rosate 360 TF
A trade and amenity-grade concentrate at roughly double the strength of a consumer bottle.
Labelled for professional use only, so the operator needs a recognised Certificate of Competence, or supervision by someone who holds one, to use it legally, even on your own property.
Professional concentrate, 490 g/L glyphosate
Gallup Hi-Aktiv 490
One of the highest-concentration glyphosate products sold in the UK, approved for hard surfaces and amenity use.
Its own label gives an exact knapsack rate, 12 ml per litre of water for general use, one litre of made-up spray treating around 40 sq m. Same certificate requirement as any professional-use product.
No affiliate links on this page, and no brand pays for a mention here. These are named for their published concentration and legal access only, not a claim that one outperforms another.
The certificate question, answered straight
There’s a real, sourced distinction here worth being straight about. HSE guidance on the Certificate of Competence is clear: anyone using a plant protection product authorised for professional use must hold the relevant NPTC or SSTS certificate, commonly starting with the PA1 theory module plus PA6 for hand-held equipment, or be working under the direct, personal supervision of someone who does, if they were born after 31 December 1964, and that requirement applies whether the spraying is commercial or on your own land. Consumer/amateur-labelled products carry no such requirement.
In practice that means a professional-strength concentrate like Rosate 360 TF or Gallup Hi-Aktiv isn’t off-limits to buy, but it does require the person actually holding the lance to be qualified, or supervised by someone who is. A consumer concentrate is the straightforward route if that’s not you.
Mixing it properly
Half-fill the tank with clean water first, add the measured concentrate, then top up to the full volume, agitating throughout rather than dumping the concentrate straight into an empty or full tank. Mix only what you plan to use in that session; both a consumer and a professional label are consistent on spraying out the same day rather than storing a made-up batch for next time.
Rinse the tank, lance and nozzle with clean water straight after spraying, before the mix has a chance to dry anywhere in the mechanism. A dried residue is the most common reason a sprayer stops working cleanly on its next outing.
About this resource
I’m The Weed Guy, one bloke who’s qualified to spray professional weedkiller. The concentrations and rates above come from the named products’ own published label data, not a lab test I’ve run myself.
The honest disclosure: nothing here is a paid-for opinion, no brand sponsors this site, and there are currently no affiliate links on this page. If that ever changes it will be disclosed plainly. Where a figure varies by pack or hasn’t been confirmed to a specific product, it’s flagged as such above rather than stated as exact.
Common questions
How much glyphosate do I actually put in per litre of water?
There is no single answer, it depends entirely on the concentration of the specific product in your hand, and that varies by a factor of nearly 5 between a diluted amateur bottle and a professional concentrate. The only reliable method is to read your product’s own label rate (usually given as millilitres of product per litre of water, or a volume per hectare in a stated water volume) and work from that, not from a rate you’ve seen quoted for a different product.
What’s the actual difference between 360 and 490 glyphosate?
Concentration, and nothing else, both are glyphosate at professional strength and both need the operator to hold the relevant certificate. Because Gallup Hi-Aktiv 490 is packed at a higher concentration than a 360 g/L product like Rosate 360 TF, you use less of it per litre of water to hit the same on-the-ground dose, its own label rate is 12 ml per litre against roughly 20-25 ml per litre commonly quoted for a 360 g/L product. Neither number tells you anything about which kills weeds more effectively when both are mixed and applied correctly.
Can I buy Gallup Hi-Aktiv or Rosate 360 TF as a homeowner?
Buying it isn’t restricted, most agricultural and amenity suppliers will sell a professional-use product to anyone. Using it legally is the part that’s restricted: HSE guidance requires the operator to hold a recognised Certificate of Competence (commonly the PA1 and PA6 modules for hand-held equipment), or to be working under the direct, personal supervision of someone who does, and this applies whether you’re spraying commercially or your own driveway. Consumer-labelled concentrates like Roundup Optima+ carry no such requirement.
How long does mixed glyphosate spray solution last once diluted?
Not long, and it isn’t designed to be stored. Manufacturer mixing guidance for both a professional concentrate and a consumer one is consistent on this: mix only as much as you’ll use that session and spray it out the same day, rather than making up a batch to use across several visits.
Do I need to add anything to glyphosate to make it work better?
For a straightforward driveway, path or patio job, no. Some professional labels do permit an authorised adjuvant for specific harder situations (dense woody weeds, for instance), but that’s a label-specific allowance, not a general upgrade, and adding an unauthorised surfactant or "booster" to any product is using it in a way its approval doesn’t cover. Getting the label’s own rate right and spraying on a dry day does more for results than anything added to the mix.
Why does my sprayed weed look fine a week later?
Most likely the dose was too weak for the amount of product you actually applied, not that glyphosate "doesn’t work" on it. Working from a rate meant for a different, weaker product, under-filling the water first so the concentrate is over-diluted, or rain within a few hours of spraying are the three most common causes, and all three come back to matching the mixing rate to the exact product you bought.